%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Feuillen, Thomas
%A Xu, Chunlei
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%A Jacques, Laurent
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T Quantity over Quality: Dithered Quantization for Compressive Radar Systems
%D 2019
%X In this paper, we investigate a trade-off between the number of radar observations (or measurements) and their resolution in the context of radar range estimation. To this end, we introduce a novel estimation scheme that can deal with strongly quantized received signals, going as low as 1-bit per signal sample. We leverage for this a dithered quantized compressive sensing framework that can be applied to classic radar processing and hardware. This allows us to remove ambiguous scenarios prohibiting correct range estimation from (undithered) quantized base-band radar signal. Two range estimation algorithms are studied: Projected Back Projection (PBP) and Quantized Iterative Hard Thresholding (QIHT). The effectiveness of the reconstruction methods combined with the dithering strategy is shown through Monte Carlo simulations. Furthermore we show that: (i), in dithered quantization, the accuracy of target range estimation improves when the bit-rate (i.e., the total number of measured bits) increases, whereas the accuracy of other undithered schemes saturate in this case; and (ii), for ﬁxed, low bit-rate scenarios, severely quantized dithered schemes exhibit better performances than their full resolution counterparts. These observations are conﬁrmed using real measurements obtained in a controlled environment, demonstrating the feasibility of the method in real ranging applications.
%K Radar
%K FMCW
%K Ranging
%K Compressive Sensing
%K Quantization
%K Dither
%K Projected Back Projection
%K Iterative Hard Thresholding
%K 1-bit
%G Anglais
%B Radar Conference 2019
%C Boston, MA, USA
%8 du 22/04/2019 au 26/04/2019
%U Handle: http://hdl.handle.net/2078.1/213366
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Feuillen, Thomas
%A Xu, Chunlei
%A Vandendorpe, Luc
%A Jacques, Laurent
%T 1-bit Localization Scheme for Radar using Dithered Quantized Compressed Sensing
%X We present a novel scheme allowing for 2D target localization using highly quantized 1-bit measurements from a Frequency Modulated Continuous Wave (FMCW) radar with two receiving antennas. Quantization of radar signals introduces localization artifacts, we remove this limitation by inserting a dithering on the unquantized observations. We then adapt the projected back projection algorithm to estimate both the range and angle of targets from the dithered quantized radar observations, with provably decaying reconstruction error when the number of observations increases. Simulations are performed to highlight the accuracy of the dithered scheme in noiseless conditionswhencomparedtothenon-ditheredandfull32-bitresolutionunderseverebit-ratereduction.Finally,measurementsare performed using a radar sensor to demonstrate the effectiveness and performances of the proposed quantized dithered scheme in real conditions.
%K Radar
%K 2D-localization
%K Quantization
%K Quantized Compressive Sensing
%K FMCW
%K Antenna array.
%G Anglais
%B Proceedings of the 5th International Workshop on Compressed Sensing applied to Radar, Multimodal Sensing, and Imaging (CoSeRa)
%D 2018
%U Handle: http://hdl.handle.net/2078.1/213363
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gueuning, Quentin
%A Craeye, Christophe
%A Oestges, Claude
%T A Stable Representation of the Transmittance Between Identical Circular Apertures
%X In recent work, the transmittance between circular apertures was formulated, thanks to the projection of equivalent currents evaluated on the apertures over Zernike polynomials, through a polynomial series of a near-field coefficient which is accurate for large apertures and low-order modes. It was observed that this expansion becomes numerically instable for low relative distances. In this paper, we derive a stable representation which can be calculated at arbitrary distance. In case of identical modes, it reduces to a closed-form expression for which an asymptotic near-field formula is given.
%G Anglais
%B Proceedings 2nd URSI Atlantic Radio Science Meeting (AT-RASC)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/204128
%R 10.23919/ursi-at-rasc.2018.8471414
%* peer-reviewed
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Feuillen, Thomas
%A Vandendorpe, Luc
%A Jacques, Laurent
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T An extreme bit-rate reduction scheme for 2D radar localization
%X In this paper, we further expand on the work in [1] that focused on the localization of targets in a 2D space using 1-bit dithered measurements coming from a 2 receiving antennae radar. Our aim is to further reduce the hardware requirements and bit-rate, by dropping one of the baseband IQ channel from each receiving antenna. To that end, the structure of the received signals is exploited to recover the positions of multiple targets. Simulations are performed to highlight the accuracy and limitations of the proposed scheme under severe bit-rate reduction.
%K Radar
%K compressive sensing
%K quantization
%K sparsity
%G Anglais
%J Proceedings of "International Traveling Workshop on Interactions Between Sparse Models and Technology"
%B Proceedings of "International Traveling Workshop on Interactions Between Sparse Models and Technology"
%D 2018
%* peer-reviewed
%D 2018
%U Handle: http://hdl.handle.net/2078.1/211764
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Ciblat, Philippe
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Effective Capacity Based Resource Allocation for Rayleigh-Fading Parallel Channels
%X We address the problem of allocating different powers amongst parallel channels when effective capacity is the performance metric and sum-power is constrained. We assume that Chase-Combining-HARQ mechanism is applied. Closed-form expressions for the powers are exhibited. Numerical comparisons with other power allocations obtained through either ergodic capacity or throughput optimizations are done.
%K HARQ
%K resource allocation
%K effective capacity
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209297
%R 10.1109/spawc.2018.8445897
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Vandendorpe, Luc
%T Energy Efficient Beamforming Design Ior Multi-Carrier Multi-user Systems with Nonlinear Amplifiers
%X The energy efficiency (EE) maximization problem is studied for the design of beamforming for multi-carrier multiuser systems. Nonlinear amplifier at each antenna as well as per-antenna power constraints at the transmitter are considered. The quality-of-service (QoS) of each user is guaranteed by a minimal transmission rate. Because the power allocation variables and the beamforming vectors are coupled in the original problem, which makes it difficult to handle, we split the problem into two subproblems. The first subproblem, which optimizes the power allocation, can be formulated as a geometric programming (GP) after the term related to power consumption is approximated as a monomial. The second subproblem, which optimizes the beamforming, is formulated as a second-order cone programming (SOCP). Numerical results illustrate the effect of EE maximization on rates and the effect of circuit power and amplifier efficiency on EE.
%K beamforming
%K multicarrier
%K beamformingenergy efficiency
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 15th International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209296
%R 10.1109/iswcs.2018.8491083
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Du, Jingbo
%A Xu, Wei
%A Zhao, Chunming
%A Vandendorpe, Luc
%T Hybrid Beamforming Design for Multiuser Massive MIMO-OFDM Systems
%X A multiuser hybrid beamforming system with orthogonal frequency division multiplexing (OFDM) is considered. We propose an alternating optimization algorithm based on manifold optimization to maximize the performance in terms of the system spectral efficiency. Moreover, two simplified methods with low complexity are also proposed which are of practical relevance for massive MIMO. The proposed methods are verified by simulation results to have smaller spectral efficiency gaps with the fully-digital beamforming than the scheme in another recent research. With the proposed designs, significant cost savings are obtained with only marginal loss in performance.
%K MIMO
%K wireless
%K hybrid beamforming
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 15th International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209290
%R 10.1109/iswcs.2018.8491217
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mirghasemi, Hamed
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Optimal Compression and Transmission Policies for Energy Harvesting Nodes
%X We consider an energy harvesting transmitter which may need to compress received packets before forwarding them over a flat fading channel. Data compression is required to meet the bandwidth or energy constraint at the cost of data distortion. The objective is to design optimal compression and transmission policies, namely optimal transmission and compression powers, transmission and compression rates and transmission and compression times, such that the total distortion is minimized. In this paper, we consider a time slotted system where new data and energy packets arrive at the beginning of each time slot (TS) and channel gains are assumed to remain constant during each TS. Under the assumption that the energy and data arrivals and channel gains are known non-causally which corresponds to offline optimization, we formulate the compression and transmission scheduling optimization as a convex optimization problem and characterize the properties of optimal scheduling. For the strict delay case where the transmission and compression of each packet must be executed within the corresponding TS, we provide an iterative algorithm which mimics the iterative directional water-filling (IDWF) algorithm. Numerical results are provided to illustrate our results and the properties of optimal scheduling.
%K energy harvesting
%K compression
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 15th International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209294
%R 10.1109/iswcs.2018.8491080
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Janatian, Nafiseh
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Optimal Offloading Strategy and Resource Allocation in SWIPT-based Mobile-Edge Computing Networks
%X In this paper, we consider a simultaneous wireless information and power transfer (SWIPT)-based mobile edge computing (MEC) system consisting of a multi-antenna access point (AP), multiple single antenna ultra-low power devices (ULPDs) and a MEC server. The objective is to process the information gathered by the ULPDs relying only on the energy obtained through RF energy harvesting (EH). To achieve this, the computation burden is partially assigned to the ULPDs and partially offtoaded to a MEC server. It is assumed that the AP simultaneously delivers power and control signals to the ULPDs by using SWIPT. The ULP network exploits the harvested energy for decoding the control message and either locally computing or offloading the tasks to the MEC server. In this scenario, we jointly optimize the offloading decisions, the time slots devoted to EH, information decoding, local computation/offloading and the offloading powers to minimize the total energy cost of the ULPDs. Numerical results illustrate the effectiveness of the proposed framework.
%K MEC system
%K wireless
%K offloading
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 15th International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209293
%R 10.1109/iswcs.2018.8491214
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Janatian, Nafiseh
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Optimal resource allocation in ultra-low power fog-computing SWIPT-based networks
%X In this paper, we consider a fog computing system consisting of a multi-antenna access point (AP), an ultra-low power (ULP) single antenna device and a fog server. The ULP device is assumed to be capable of both energy harvesting (EH) and information decoding (ID) using a time-switching simultaneous wireless information and power transfer (SWIPT) scheme. The ULP device deploys the harvested energy for ID and either local computing or offloading the computations to the fog server depending on which strategy is most energy efficient. In this scenario, we optimize the time slots devoted to EH, ID and local computation as well as the time slot and power required for the offloading to minimize the energy cost of the ULP device. Numerical results are provided to study the effectiveness of the optimized fog computing system and the relevant challenges.
%K Resource allocation
%K fog network
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2018 IEEE Wireless Communications and Networking Conference (WCNC)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209298
%R 10.1109/wcnc.2018.8376974
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Vandendorpe, Luc
%T Power Allocation for Energy Efficiency Optimization in Distributed Antenna Systems
%X An energy efficiency (EE) maximization problem with multiple distributed antennas is considered in this paper. Besides the constraint on the total transmit power and per-antenna transmit power constraints, an additional constraint dealing with total weighted power is introduced. Moreover, a Quality-of-Service (QoS) constraint is introduced. Because the original problem is a fractional convex one, Dinkelbach's algorithm is implemented to reformulate the problem. By investigating the Karush- Kuhn-Tucker (KKT) conditions, the mathematical properties of the globally optimal solution are studied and proved, which provides a deeper understanding of the structure of power allocation among antennas. Numerical results demonstrate the effect of QoS on EE and also the structure of power allocation.
%K mimo
%K power allocation
%K distributed mimo
%K wireless
%K ICTM:SIGN
%K ICTM:COMM
%G Anglais
%B 2018 15th International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/209292
%R 10.1109/iswcs.2018.8491042
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wiame, Charles
%A Vandendorpe, Luc
%A Oestges, Claude
%T Stochastic Geometry Based Coverage Estimation Using Realistic Urban Shadowing Models
%X The main contribution of this paper consists in integrating a physically correlated shadowing model of the aggregate interference in a stochastic geometry-based approach. The considered shadowing takes place in a Manhattan urban grid and combines both penetration and corner diffraction when modeling signal transmission from base stations to users. A tractable expression for the network coverage probability is obtained thanks to the framework of stochastic geometry. Our results suggest that the diffracted mechanisms are dominant compared to building penetration. It is also shown that the second order diffracted signal have little impact on the coverage compared to the first order signals.
%G Anglais
%B Proceedings IEEE 87th Vehicular Technology Conference (VTC Spring)
%I IEEE
%D 2018
%U Handle: http://hdl.handle.net/2078.1/204129
%R 10.1109/vtcspring.2018.8417471
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Miao, Yang
%A Gueuning, Quentin
%A Gan, Mingming
%A Oestges, Claude
%T Adding diffuse scattering correlation to effective roughness models in ray tracing
%X This paper proposes to add diffuse scattering correlation to Effective Roughness (ER) models used in ray tracing. Diffuse scattering correlation is modeled by phase evolution models including a deterministic part and a correlated (random) part. The deterministic part is dependent on the distance variations between the moving terminal and each ER tile, and the correlated part is related to the angular variations. The predicted narrowband radio channels by ray tracing with proposed diffuse scattering correlation are compared with those obtained by applying a reference physical optics approach, in terms of the properties over spatial frequency.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 11th European Conference on Antennas and Propagation (EUCAP)
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188000
%R 10.23919/EuCAP.2017.7928171
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Cespedes, Maximo Morales
%A Plata-Chaves, Jorge
%A Armada, Ana Garcia
%A Moonen, Marc
%A Vandendorpe, Luc
%T Can the Use of Reconfigurable Antennas Overcome the CSI Bottleneck for FDD Massive MIMO?
%X Massive MIMO has been proposed as a means of achieving huge spectral efficiency in cellular networks. However, its implementation is usually based on linear precoding schemes using Channel State Information (CSI). For this reason, the use of the Time Division Duplex (TDD) mode is typically assumed since it removes the dependence on the number of antennas at the transmitter to acquire CSI. Unfortunately, most of the cellular network operate in the Frequency Division Duplex (FDD) mode in which the acquisition of CSI depends proportionally to the number of transmit antennas. For this reason, the implementation of Massive MIMO is handicapped to few transmit antennas for the current cellular networks. In this paper we study the use of reconfigurable antennas that can switch among a set of preset modes, i.e., radiation patterns, through Blind Interference Alignment schemes. We show that it is a solution to exploit a very large number of antennas at the transmit side, overcoming the bottleneck that today constitutes the acquisition of CSI in Massive MIMO systems operating in FDD mode.
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2017 IEEE Wireless Communications and Networking Conference (WCNC)
%I IEEE
%D 2017
%U Handle: http://hdl.handle.net/2078.1/189876
%R 10.1109/wcnc.2017.7925735
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wiame, Charles
%A Vandendorpe, Luc
%A Oestges, Claude
%T Comparison of Access Point Distributions and Beamforming Strategies for Massive MIMO Networks : a Stochastic Geometry Approach
%X Strategies are developed to optimize the downlink performance of a massive MIMO network constrained to a fixed global transmit power and a fixed total number of transmit antennas. Two possible degrees of freedom are analysed : the distribution of the base stations and the beamforming technique. Two different shadowing environments are considered as well. The network performance is evaluated either by means of Monte Carlo simulations, or using analytical expressions derived thanks to stochastic geometry. The results suggest that the coverage probability increases with the numbers of base stations and the cluster size.
%K ICTEAM:COMM
%G Anglais
%B Proceedings of the 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2017)
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188103
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Makhoul, Gloria
%A Mani, Francesco
%A D'Errico, Raffaele
%A Oestges, Claude
%T Doppler characteristics for indoor mobile-to-mobile channels
%X This paper analyzes Doppler spectra of mobile-to-mobile (M2M) channels, based on a measurement campaign carried out in an indoor environment at 2.48 GHz. The Doppler spectrum is characterized in line-of-sight (LOS) and non-line-of-sight (NLOS) environments for different types of pedestrian movements. Subsequently, an analytical Doppler spectrum model is proposed and successfully compared to the measurement data.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 11th European Conference on Antennas and Propagation (EUCAP)
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188001
%R 10.23919/EuCAP.2017.7928150
%R 10.23919/EuCAP.2017.7928150
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Université catholique de Louvain (UCL) - SST/ICTM/INMA - Pôle en ingénierie mathématique
%A Torrea-Duran, Rodolfo
%A Rosas, Fernando
%A Tsiaflakis, Paschalis
%A Pollin, Sofie
%A Orozco, Aldo
%A Vandendorpe, Luc
%A Moonen, Marc
%T Double Relay Communication Protocol with power control for achieving fairness in cellular systems
%X The growing demand for wireless connectivity has turned bandwidth into a scarce resource that has to be carefully managed and fairly distributed to users. However, the variability of the wireless channel can severely degrade the service received by each user. The Double Relay Communication Protocol (DRCP) [1] is a transmission scheme that addresses these problems by exploiting spatial diversity to enhance the fairness of the system without requiring any additional infrastructure (i.e relay nodes or a backhaul connection). Although DRCP has originally been proposed to work without channel state information at the transmitter (CSIT), in this paper we study how the performance of DRCP can be further improved through power control when CSIT is available. Our approach provides the highest fairness and the largest minimum spectral efficiency for most conditions compared to other studied baseline approaches.
%K ICTM:COMM
%K ICTM:SIGN
%G Anglais
%B 2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)
%I IEEE
%D 2017
%U Handle: http://hdl.handle.net/2078.1/189875
%R 10.1109/icassp.2017.7952832
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%A Dementieva, Natalia
%A Vinogradov, Evgenii
%T Evaluation of Large-Scale Parameters in Urban Microcells at 3.8 GHz
%X This paper evaluates MIMO radio channel measurements at 3.8 GHz, conducted in various urban microcell environments in Louvain-la-Neuve. Large-scale parameters, such as shadow fading, delay and angular spreads, are extracted and compared with values provided by existing models (COST 273, COST 2100 and 3GPP- 3D).
%K ICTEAM:COMM
%G Anglais
%B Proceedings of the XXXIInd URSI General Assembly and Scientific Symposium
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188012
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%A Dementieva, Natalia
%A Vinogradov, Evgenii
%T Experimental Characterization of Geometry-Based Channel Models in Suburban Microcells
%X This paper evaluates MIMO radio channel measurements at 3.8 GHz, conducted in various urban microcellular environments in the city of Louvain-la-Neuve, Belgium. Large-scale parameters, such as shadow fading, delay and angular spreads as well as dense multipath power are extracted and compared with values provided by existing models. A joint specular-dense multipath cluster-based model is then parametrized from the experimental data, detailing cluster spread and correlation properties.
%K ICTEAM:COMM
%G Anglais
%B Proceedings of the 28th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2017)
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188105
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Nguyen, Trung-Hien
%A Rottenberg, François
%A Gorza, Simon-Pierre
%A Louveaux, Jérôme
%A Horlin, François
%T Extended Kalman filter for carrier phase recovery in optical filter bank multicarrier offset QAM systems
%X We investigate the carrier phase recovery using extended Kalman filter in optical filter bank multicarrier offset-QAM systems. The proposed method is of low complexity and its performance is comparable to the state-of-the-art BPS method.
%G Anglais
%B Proceedings of the 2017 Optical Fiber Communications Conference and Exhibition
%D 2017
%U Handle: http://hdl.handle.net/2078.1/187823
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Nguyen, Trung-Hien
%A Gorza, Simon-Pierre
%A Horlin, François
%A Louveaux, Jérôme
%T ML and MAP phase noise estimators for optical fiber FBMC-OQAM systems
%X This paper addresses the carrier phase recovery problem in Offset-QAM-based filterbank multicarrier (FBMC-OQAM) systems. The combined phase noise coming from the transmit and receive lasers, is known to induce a phase rotation of the demodulated symbols at the receiver. Several approaches have been proposed to recover the phase in FBMC-OQAM communication systems on optical fiber. Most of them have a significant complexity and do not make use of all information at disposal. In this paper, we propose two new estimators, obtained by minimizing a maximum likelihood (ML) and a maximum a posteriori (MAP) criteria. They use an error model formulation which allows to easily use priors on the phase noise statistics. By linearization of the error, an analytical solution is found for the phase error, which avoids the need for multiple phase tests. Simulation results demonstrate the better performance of the proposed estimators with respect to state of the art solutions in the low signal-to-noise (SNR) regime and for a small number of subcarriers.
%G Anglais
%B Proceedings of the 2017 IEEE International Conference on Communications
%D 2017
%U Handle: http://hdl.handle.net/2078.1/187821
%R 10.1109/ICC.2017.7996768
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Hanssens, Brecht
%A Martinez-Ingles, Maria-Teresa
%A Tanghe, Emmeric
%A Plets, David
%A Molina-Garcia-Pardo, Jose-Maria
%A Oestges, Claude
%A Martens, Luc
%A Joseph, Wout
%T Polarimetric analysis of reverberation times for 94 GHz indoor communication
%X This paper presents a measurement-based analysis of both the specular- and dense multipath components (SMC and DMC) at 94 GHz in an indoor environment. A total of 15 positions were measured with a virtual antenna array system, from which we have calculated Power Delay Profiles (PDP). A method was developed that allowed for the full-polarimetric estimation of the specular propagation paths, after which the remainder was regarded as the diffuse spectrum. The behavior of the reverberation time, known from the theory of room electromagnetics, was analyzed based on this diffuse spectrum.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 11th European Conference on Antennas and Propagation (EUCAP)
%D 2017
%U Handle: http://hdl.handle.net/2078.1/188002
%R 10.23919/EuCAP.2017.7928035
%R 10.23919/EuCAP.2017.7928035
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Vandendorpe, Luc
%T Resource allocation and subcarrier pairing in energy efficient relay-assisted OFDMA downlink systems
%X The energy efficiency (EE) maximization problem in amplify-and-forward (AF) relay-assisted downlink channels with orthogonal frequency-division multiple access (OFDMA) is studied. The power allocation is optimized together with subcarrier allocation and pairing at the relay. As the base station and the relay have individual power constraints, an alternating optimization approach is adopted to solve the problem. Numerical results show that the proposed algorithm outperforms other benchmark schemes in terms of EE.
%K ICTM:SIGN
%K ICTM:COMM
%G Anglais
%B 2017 International Symposium on Wireless Communication Systems (ISWCS)
%I IEEE
%D 2017
%U Handle: http://hdl.handle.net/2078.1/189878
%R 10.1109/iswcs.2017.8108121
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Mestre, Xavier
%A Horlin, François
%A Louveaux, Jérôme
%T Single-tap equalizer for MIMO FBMC systems under doubly selective channels
%X Offset-QAM-based filterbank multicarrier (FBMC-OQAM) modulations are known to progressively loose their orthogonality as the channel gets more selective in time and frequency. The effect of channel frequency selectivity on FBMC-OQAM systems has been extensively studied in the literature. Many compensations methods have been proposed to combat it. However, most of them have a significant implementation complexity and do not take into account the time selective nature of the channel. In this paper, we propose a MIMO equalizing structure for doubly selective channel based on a simple single-tap per-subcarrier decoding matrix. The decoding matrices are designed to minimize the mean squared error of the symbol estimate. This decoder exploits the degrees of freedom offered by the extra antennas at the receiver to compensate for the distortion induced by time and frequency selectivity. Simulation results demonstrate the performance gain of the proposed design with respect to classical designs.
%G Anglais
%B Proceedings of the 2017 IEEE International Conference on Acoustics, Speech and Signal Processing
%D 2017
%U Handle: http://hdl.handle.net/2078.1/187820
%R 10.1109/ICASSP.2017.7952864
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Torrea-Duran, Rodolfo
%A Morales-Cespedes, Maximo
%A Plata-Chaves, Jorge
%A Vandendorpe, Luc
%A Moonen, Marc
%T Topology-aware space-time network coding
%X Space-Time Network Coding (STNC) is a time division multiple access (TDMA)-based scheme that combines network coding and space-time coding by allowing relays to combine the information received from different sources during the transmission phase and to forward the combined signal to a destination in the relaying phase. However, STNC schemes require all the relays to overhear the signal transmitted from all the sources in the network and also a large number of time-slots to achieve full diversity in a multipoint-to-multipoint transmission, which is particularly challenging for large cellular networks. In this paper, we exploit a basic knowledge of the network topology, i.e. the knowledge of the base stations overheard by other base stations and users, to reduce drastically the number of time-slots. Our results show that our scheme is able to increase the spectral efficiency with a marginal decrease of the spatial diversity compared to traditional STNC.
%K ICTM:SIGN
%K ICTM:COMM
%G Anglais
%B 2017 25th European Signal Processing Conference (EUSIPCO)
%I IEEE
%D 2017
%U Handle: http://hdl.handle.net/2078.1/189879
%R 10.23919/eusipco.2017.8081182
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Morales Cespedes, Maximo
%A Plata-Chaves, J.
%A Armada, A.G.
%A Vandendorpe, Luc
%T A blind interference alignment scheme for practical channels
%K ICTEAM
%K ICTEAM/COMM
%K ICTEAM/SIGN
%G Anglais
%B Communications (ICC), 2016 IEEE International Conference on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176762
%R 10.1109/ICC.2016.7511077
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%T A new multiobjective game for the design of wireless transceivers with local coordination ability
%K ICTEAM
%K ICTEAM/COMM
%K ICTEAM/SIGN
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2016 IEEE 17th International Workshop on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176756
%R 10.1109/SPAWC.2016.7536748
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Castel, Thijs
%A Lemey, Sam
%A Agneessens, Sam
%A Van Torre, Patrick
%A Rogier, Hendrik
%A Oestges, Claude
%T Adaptive Subcarrier Modulation for Indoor
Public Safety Body-to-Body Networks
%X In this contribution, we present the Bit Error Rate characteristics for an indoor, wideband body-to-body channel between two firefighters when using IEEE 802.11 ac, which is proven a very suitable standard for future, wideband public safety networks. Moreover, the BER and throughput charac- teristics, when applying both transmission blocking, fixed and adaptive, subcarrier modulation are presented. These charac- teristics show an increased throughput when applying adaptive subcarrier modulation. We have conducted a wideband, indoor channel sounder campaign at 3.6 GHz with 120 MHz useful bandwidth, simulating real-life rescue operations performed by two simultaneously moving members of the Rapid Intervention Team. Both firefighters were equipped with low-profile, light- weight and energy-efficient Ultra Wideband Cavity-Backed slot antennas in Substrate Integrated Waveguide technology, unobtru- sively deployed inside the front and back sections of their jackets, providing 2 × 2 MIMO capability.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th European Conference on Antennas and Propagation (EuCAP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179927
%R 10.1109/EuCAP.2016.7481822
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN-Pôle en ingénierie électrique
%A Hanssens, Brecht
%A Plets, David
%A Tanghe, Emmeric
%A Oestges, Claude
%A Gaillot, Davy P.
%A Lienard, Martine
%A Martens, Luc
%A Joseph, Wout
%T An indoor localization technique based on ultra-wideband AoD/AoA/ToA estimation
%X This work presents a novel localization scheme based on Ultra-Wideband (UWB) channel sounding, employing a triangulation method that makes use of the geometrical properties of propagation paths, such as time of arrival (ToA), angle of departure (AoD) and angle of arrival (AoA). An extension to the high-resolution RiMAX algorithm was developed, facilitating the analysis of UWB frequency-dependent propagation parameters, allowing for the localization of a target node in Line-of-Sight (LoS), Obstructed-LoS (OLoS), and Non-LoS (NLoS) scenarios.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 2016 IEEE International Symposium on Antennas and Propagation
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179919
%R 10.1109/APS.2016.7696429
%R 10.1109/APS.2016.7696429
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Pairon, Thomas
%A Craeye, Christophe
%A Oestges, Claude
%T Doppler Spectrum of a Rotating Smooth Cylinder
%X The Doppler spectrum of a rotating smooth cylinder is investigated both theoretically and experimentally. Since the studied object has a smooth surface and is large compared to the wavelength, the physical optics (PO) approximation is used. The integration of the surface currents is computed with a hybrid method which consists of integrating analytically the currents in one dimension using the stationary phase method (SPM), while the currents in the other dimension are integrated numerically. This enables a reduction of the computation time compared to a fully numerical integration. Simulations are compared with measurements.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th European Conference on Antennas and Propagation (EuCAP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179924
%R 10.1109/EuCAP.2016.7482004
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Energy efficiency-rate multiobjective Game: Tradeoffs, scalarisation techniques and distributed implementation
%K ICTEAM
%K ICTEAM/SIGN
%K ICTEAM/COMM
%G Anglais
%B Communications (ICC), 2016 IEEE International Conference on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176761
%R 10.1109/ICC.2016.7511343
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Vandendorpe, Luc
%T Energy efficient power allocation and relay selection in MIMO relay channels
%X In this paper, we consider the energy efficiency (EE) maximization problem for MIMO-relay channels with relay selection and individual power constraints for each node. We implement Dinkelbach's method for the whole system to iteratively select the relays. Closed-form expressions of the precoding matrix at the source and the beamforming matrix at the selected relay are obtained thanks to the concavity of the objective function. We also give the mathematical property of monotonicity which guarantees that the values of Lagrangian multipliers can always be found. Finally, we give the numerical results illustrating the performance gain due to relay selection.
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B 2016 IEEE 27th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/181377
%R 10.1109/PIMRC.2016.7794640
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Z.
%A Vandendorpe, Luc
%T Energy efficient resource allocation in MIMO-OFDMA downlink systems
%K ICTEAM
%K ICTEAM/SIGN
%K ICTEAM/COMM
%G Anglais
%B Proceedings of SPAWC 2016
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176755
%R 10.1109/SPAWC.2016.7536842
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Torrea-Duran, R.
%A Rosas, F.
%A Pollin, S.
%A Vandendorpe, Luc
%A Moonen, M.
%T Energy-efficient Double Relay Communication Protocol in cellular networks
%K ICTEAM
%K ICTEAM/SIGN
%K ICTEAM/COMM
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2016 IEEE 17th International Workshop on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176759
%R 10.1109/SPAWC.2016.7536880
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gueuning, Quentin
%A Hubert, Simon
%A Craeye, Christophe
%A Oestges, Claude
%T Error model for Contour-FFT evaluation of the free-space on-plane Green's function
%X Closed-form analytical expressions are derived for the numerical integration of the spectral Green's function with Contour-FFT. Results indicates that a proper uniform grid of spatial points enhances the convergence rate of the truncation error, that the Nyquist-Shannon theorem can be generalized to inverse Laplace transforms on linear path and that the relative error specific to Contour-FFT is a regularized gamma function. Two examples illustrate the modularity of the approach.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 2016 URSI International Symposium on Electromagnetic Theory (EMTS)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179922
%R 10.1109/URSI-EMTS.2016.7571383
%R 10.1109/URSI-EMTS.2016.7571383
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Horlin, François
%A Kofidis, Eleftherios
%A Louveaux, Jérôme
%T Generalized optimal pilot allocation for channel estimation in multicarrier systems
%X This paper addresses the design of MSE-optimal preambles for multicarrier channel estimation under a maximum likelihood or minimum mean squared error criterion. The derived optimality condition gives insight on how to allocate the pilots that compose the preamble. While many papers show that equispaced and equipowered allocation is optimal, the generalized condition demonstrates that there exist many different configurations that offer the same optimal performance. Furthermore, the condition applies not only to maximum likelihood but also to minimum mean squared error channel estimation. An application of the generalized condition in the presence of inactive subcarriers (virtual subcarriers problem) is shown such that a non equispaced allocation can achieve the same optimal performance as if an equispaced one could be used.
%G Anglais
%B Generalized optimal pilot allocation for channel estimation in multicarrier systems
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179884
%R 10.1109/SPAWC.2016.7536847
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Shrestha, Jeevan
%A Vandendorpe, Luc
%T Joint clock parameter and transmitter position estimation using TDOA in one way packet transmission
%K ICTEAM
%K ICTEAM/COMM
%K ICTEAM/SIGN
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2016 IEEE 17th International Workshop on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176757
%R 10.1109/SPAWC.2016.7536791
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Janatian, Nafiseh
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Joint multi-objective transmit precoding and receiver time switching design for MISO SWIPT systems
%K ICTEAM
%K ICTEAM/COMM
%K ICTEAM/SIGN
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2016 IEEE 17th International Workshop on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176758
%R 10.1109/SPAWC.2016.7536838
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vinogradov, Evgenii
%A Joseph, Wout
%A Oestges, Claude
%T MIMO Indoor Propagation: A Geometry-Based Model Including Time-Variant Fading Statistics
%X A geometry-based reference model for Second Order Scattering Fading (SOSF) distributed multiple-input-multipleoutput (MIMO) channels is proposed for mobile-to-mobile scenarios. From this model, a spatial correlation function is derived. The time-variant nature of channel statistics is modeled by using a Hidden Markov Model (HMM) based approach. The proposed method enables to implement a generator of channel realizations for a wide range of indoor MIMO channels, including Fixedto- Mobile and Mobile-to-Mobile transmission; Rician, Rayleigh, Double Rayleigh, Second Order Scattering fading, etc.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th European Conference on Antennas and Propagation (EuCAP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179926
%R 10.1109/EuCAP.2016.7481948
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gusi-Amigo, Adria
%A Ciosas, Pau
%A Vandendorpe, Luc
%T Mean square error performance of sample mean and sample median estimators
%X Based on the Ziv-Zakai methodology to bound estimators, we derived an estimation bound able to predict the mean square error degradation due to model mismatches. In this article, we build upon this result to provide a performance comparison between mean and median estimators in the presence of outliers. The latter is well known to be statistically more robust than the mean in the presence of outliers. Here we show this superiority by comparing their theoretical error bounds. Analytical results are obtained, which are validated by computer simulations.
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B 2016 IEEE Statistical Signal Processing Workshop (SSP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/181378
%R 10.1109/SSP.2016.7551739
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Optimal precoder design for MIMO-OFDM: Understanding the role of power amplifiers and nonlinear distortion noise
%K ICTEAM
%K ICTEAM/SIGN
%K ICTEAM/COMM
%G Anglais
%B Communications (ICC), 2016 IEEE International Conference on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176763
%R 10.1109/ICC.2016.7511186
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Mestre, Xavier
%A Louveaux, Jérôme
%T Optimal zero forcing precoder and decoder design for multi-user MIMO FBMC under strong channel selectivity
%X This paper investigates the optimal design of precoders or decoders under a channel inversion criterion for multi-user (MU) MIMO filterbank multicarrier (FBMC) modulations. The base station (BS) is assumed to use a single tap precoding/decoding matrix at each subcarrier in the downlink/uplink, resulting in a low complexity of implementation. The expression of the asymptotic mean squared error (MSE) for this precoding/decoding design in the case of strong channel selectivity is recalled and simplified. Optimizing the MSE under a channel inversion constraint, the expression of the optimal precoding/decoding matrix is found. It is shown that as long as the number of BS antennas is larger than the number of users, the optimized precoder and decoder can compensate for the channel frequency selectivity and even restore the system orthogonality for a large enough number of BS antennas.
%G Anglais
%B LINEAR RECEIVERS FOR MASSIVE MIMO FBMC/OQAM UNDER STRONG CHANNEL FREQUENCY SELECTIVITY
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179883
%R 10.1109/ICASSP.2016.7472336
%R 10.1109/ICASSP.2016.7472336
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A El Soussi, M.
%A Vu, T.X.
%A Nguyen, H.N.
%A Duhamel, P.
%A Alberge, F.
%A Vandendorpe, Luc
%T Semi-orthogonal MARC with half duplex relaying: A backward compatible cooperative network with interference channels
%K ICTEAM
%K ICTEAM/SIGN
%K ICTEAM/COMM
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2016 IEEE 17th International Workshop on
%D 2016
%U Handle: http://hdl.handle.net/2078.1/176760
%R 10.1109/SPAWC.2016.7536879
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Feuillen, Thomas
%A Mallat, Achraf
%A Vandendorpe, Luc
%T Stepped frequency radar for automotive application: Range-Doppler coupling and distortions analysis
%X In this paper, the use of the stepped frequency modulation for an automotive application is studied. This modulation suffers from range-Doppler coupling and quadratic phase variations. To address this issue, a repetitive modulation scheme is used. To remain at a low computational cost, the choice is made to base the range and velocity estimation on IDFTs, thereby making the range-Doppler coupling and quadratic phase variations distortions. The effects of these distortions are studied and a compensation method is introduced. The performance of the compensation method is illustrated by means of simulation results.
%K ICTEAM
%K ICTEAM:SIGN
%K ICTEAM:COMM
%G Anglais
%B Military Communications Conference, MILCOM 2016 - 2016 IEEE
%D 2016
%U Handle: http://hdl.handle.net/2078.1/181376
%R 10.1109/MILCOM.2016.7795443
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Makhoul, Gloria
%A Mani, Francesco
%A D'Errico, Raffaele
%A Oestges, Claude
%T Time Correlation Properties of Dynamic Mobile to Mobile Channels in Indoor Environments
%X This paper analyzes the temporal correlation properties of mobile-to-mobile (M2M) channels, based on an extensive measurement campaign carried out in an indoor environment at 2.48 GHz. In order to model the dynamic channel characteristics, short- and long-term fading behaviors are extracted. The autocorrelation function (ACF) is characterized for different types of pedestrian movements. Finally the results of a channel model implementation preserving the ACF properties are presented, showing good match with those obtained from measurements.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th European Conference on Antennas and Propagation (EuCAP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179925
%R 10.1109/EuCAP.2016.7481961
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Henao, Daniel Hincapie
%A Louveaux, Jérôme
%A Maierbacher, Gerhard
%T Towards a Range-Enhanced and Spectrum-Friendly G.fast
%X The first standardized version of G.fast has been conceived to provide gigabit internet access from the distribution point (DP). Low transmit levels along its operational frequency range and low maximum aggregate transmit power (MAXATP) have been specified to restrict its electromagnetic emissions and enable the use of power available at customer premises to feed its access systems. Power constraints and a maximum bit-constellation size (Bmax=12 bits) limit its coverage and data rates, which could discourage service providers to deploy G.fast. This work analyzes different strategies that could be potentially pursued to enhance its coverage and improve its spectral compatibility with VDSL2 systems. We carry out an extensive simulation study to evaluate a) capacity boundaries of current G.fast systems; b benefits of increasing MAXATP, Bmax and power spectrum density (PSD) mask levels; and c) spectral shaping as means to improve G.fast compatibility. Our simulation results show that increasing MAXATP and Bmax boosts data rates and coverage in short loop scenarios, whereas improvements in long loops performance are only determined by MAXATP. Since such modifications generally increase the interference on legacy systems, we propose to perform power back-off (PBO) in order to improve G.fast spectrum-compatibility. As a proof of concept we adopt the PBO from VDSL2 with a fixed parameter set. Although clearly not optimized for the combination of TDD G.fast and FDD legacy systems and despite the simplicity of the adopted approach, our results indicate that spectral shaping can be an effective means to turn G.fast into a more spectrum-friendly system.
%K Standards
%K DSL
%K Transceivers
%G Anglais
%B Proc. 2016 IEEE Global Communications Conference (GLOBECOM)
%I IEEE
%D 2016
%U http://ieeexplore.ieee.org/document/7842337/
%U Handle: http://hdl.handle.net/2078.1/195036
%R 10.1109/glocom.2016.7842337
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN-Pôle en ingénierie électrique
%A Gueuning, Quentin
%A Craeye, Christophe
%A Oestges, Claude
%T Unequally-spaced fast Laplace transform for Green's function evaluation
%X A fast method for the radiation analysis of arbitrary oriented planes is presented. It combines an adaptive spectral integration scheme and a recently proposed unequally-spaced fast Laplace transform algorithm. It is illustrated on the free-space Green's function through an example where an important speed-up factor is evaluated compared to the brute force spectral integration.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 2016 URSI International Symposium on Electromagnetic Theory (EMTS)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179920
%R 10.1109/URSI-EMTS.2016.7571477
%R 10.1109/URSI-EMTS.2016.7571477
%* peer-reviewed
%0 Book Section
%9 Conférence invitée / Keynote
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%T Vehicular Channel Characterization and Modeling
%X Vehicle-to-vehicle transmissions have emerged as a key component of future communication standards, whose design and testing critically depends upon the understanding of propagation mechanisms. An important and specific aspect of vehicular communication channels lies in the fact that these are essentially non-stationary. Hence, this communication addresses two recent contributions in the field of non-stationary vehicular propagation, based on extensive measurements conducted at 5.3 GHz in suburban, urban, and underground parking areas. First, the estimation of quasi-stationarity regions is addressed by means of various metrics. It is found that the size of quasi-stationarity regions ranges from 3 to 80 m and is strongly affected by bandwidth and array configurations. A second contribution consists in proposing a dynamic wideband directional channel model. This model incorporates both angular and delay domain properties as well as the dynamic evolution of multipath components, relying on a birth-survival-death process between successive stationarity regions.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th European Conference on Antennas and Propagation (EuCAP)
%D 2016
%U Handle: http://hdl.handle.net/2078.1/179928
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A He, Ruisi
%A Renaudin, Olivier
%A Kolmonen, Veli-Mati
%A Haneda, Katsuyuki
%A Zhong , Zhangdui
%A Hubert, Simon
%A Oestges, Claude
%T Angular Dispersion Characterization of Vehicle-to-Vehicle Channel in Cross-Road Scenarios
%X Vehicle-to-vehicle (V2V) communication based collision avoidance systems detect if two vehicles are on a collision course, which are particularly useful in the absence of line-of-sight (LOS) owing to buildings, roadside infrastructures, and road bending. This paper presents an empirical study of V2V propagation channels in two suburban cross-road scenarios, where vehicles are either moving in the same direction and separate each other, or passing each other in opposite directions at the crossing. The quasi-stationarity interval is characterized using correlation matrix distance (CMD). Angular dispersions are found to be significantly affected by the type of cross-road and the presence of a LOS. By comparing the results of the different cross-roads, it is found that the angular dispersion is large in the first type of cross-road. By contrast, in the second type of cross-road, small angular dispersion is observed due to the road bending and obstruction by roadside trees.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 9th European Conference on Antennas and Propagation (EuCAP)
%I IEEE
%D 2015
%U Handle: http://hdl.handle.net/2078.1/167797
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%A Hennaux, Gauthier
%A Gueuning, Quentin
%T Centimeter- and Millimeter-Wave Channel Modeling Using Ray-Tracing for 5G Communications
%X A ray-tracing tool, including specular reflection, diffraction and attenuation by foliage, is experimentally validated at 12 and 30 GHz in a suburban environment. The tool is then applied to double directional channel modeling at 30 GHz in a real-world urban area in downtown Brussels. Azimuth-, elevation- and delay-spread are computed and analyzed on a stochastic viewpoint. It is found that elevation spreads remain limited (below 3 degrees), while azimuth-spreads are on average similar at both sides of the link (with a mean value of 12 degrees). Delay-spreads vary significantly over the user’s locations, with a mean value of 45 nanoseconds. They are positively correlated with the directional spreads at the base station. Finally, an investigation about the impact of microscopic surface roughness is conducted: it is found that it is mostly negligible at millimeter waves, unless extremely narrow beamwidth antennas are used.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE 82nd Vehicular Technology Conference (VTC Fall)
%D 2015
%U Handle: http://hdl.handle.net/2078.1/179939
%R 10.1109/VTCFall.2015.7390862
%R 10.1109/VTCFall.2015.7390862
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%T Channel dynamics in body area networks: Recent results and challenges
%X Recent results about body area radio channel dynamics are analyzed, considering on-body and body-to-body transmissions. Investigations are based on experimental data around 4 GHz. Regarding the on-body case, the dynamics of cross-channel correlation are measured and analyzed for stationary periodic and non-stationary motions, with a clear impact of the walking mode being observed. For body-to-body scenarios, measurements conducted in room-to-room environments show again some strong non-stationary behaviors. In both cases, Markov chain-based models are developed to represent transitions between fading states.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 49th Asilomar Conference on Signals, Systems and Computers
%D 2015
%U Handle: http://hdl.handle.net/2078.1/179932
%R 10.1109/ACSSC.2015.7421260
%R 10.1109/ACSSC.2015.7421260
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Hanssens, Brecht
%A Tanghe, Emeric
%A Martens, Luc
%A Oestges, Claude
%A Joseph, Wout
%T Doppler analysis of an indoor university-hall
%X An analysis of delay-Doppler characteristics in the presence of moving people is presented for short-range communications in an indoor environment. Channel sounding measurements have been carried out at 3.6 GHz in a crowded university-hall during short and long breaks between courses. The measurements reveal a difference between the RMS Doppler spread of both breaks, indicating a distinctive power distribution of their Doppler spectra. In addition, there is a significant contrast between the Doppler characteristics of the co- and cross-polarizations. Looking at the behavior of both the Doppler- and RMS Doppler spread, we also highlight the importance of characterizing multipaths in the environment.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 9th European Conference on Antennas and Propagation (EuCAP)
%I IEEE
%D 2015
%U Handle: http://hdl.handle.net/2078.1/167817
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/IMMC - Institute of Mechanics
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%A Carlier d'Odeigne, Olivier
%A Ducarme, Delphine
%T Encadrer et évaluer des stages en entreprise - analyse d'un dispositif mis en place à l’École Polytechnique de Louvain
%X Le dispositif de stages en entreprise mis en place à l’Ecole Polytechnique de Louvain est décrit et analysé au regard de la littérature. Si les objectifs et leur évaluation sont bien en ligne avec les théories pédagogiques, la principale faiblesse reste le manque d’échanges entre le responsable académique et le maître de stage.
%K Stages en entreprise
%K intégration professionnelle
%K évaluation.
%K UCL - EPL
%G Français
%B Questions de pédagogies dans l'enseignement supérieur - Innover, comment et pourquoi? Actes du 8ème colloque
%E Multiples
%I QPES
%C Brest
%D 2015
%S QPES
%U Handle: http://hdl.handle.net/2078.1/161373
%* peer-reviewed
%7 Actes du 8ème colloque - Brest INSA
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Shrestha, Jeevan
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Energy Efﬁcient Precoding for MIMO Cyclic Preﬁxed Single Carrier Communications
%X This paper addresses the design of energy efﬁcient precoding/decoding strategies for multiple-input multiple-output cyclic preﬁxed single carrier (MIMO CP-SC) systems with frequency-domain equalization. We opt for eigenbeamforming in the frequency domain for spatial precoding and decoding. We show that eigenbeamforming leads to a simple yet effective maximization of the energy efﬁciency (EE) of the MIMO CP-SC link. Moreover, the associated power allocation relies on the combination of waterﬁlling among the spatial streams and a proper distribution of the per-stream allocated power among subcarriers. Numerical results show that, if we account for the efﬁciency of the high power ampliﬁer (HPA) associated with the peak-to-average power ratio (PAPR), CP-SC can be more energy efﬁcient than orthogonal frequency division multiplexing (OFDM) for moderate to high signal-to-noise (SNR) values.
%G Anglais
%B 16th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2015
%D 2015
%U Handle: http://hdl.handle.net/2078.1/162512
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Zijian
%A Stupia, Ivan
%A Vandendorpe, Luc
%T Energy efficient precoder design for MIMO-OFDM with rate-dependent circuit power
%X This paper studies an energy efﬁcient design of pre-coder for point-to-point Multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. Dif-ferently from traditional approaches, the optimal power allo-cation strategy is studied by modelling the circuit power as a rate-dependent function. We show that if the circuit power is a constant plus an increasing and convex function of the transmission rate, the energy efﬁciency maximization problem can be reformulated as a convex fractional program and solved by means of a simple bisection algorithm. The impact of the system parameters is mathematically analyzed and then conﬁrmed by means of computational results.
%G Anglais
%B Proceedings of IEEE international conference on communications
%I IEEE
%D 2015
%U Handle: http://hdl.handle.net/2078.1/162516
%R 10.1109/ICC.2015.7248602
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Font-Bach, Oriol
%A Bartzoudis, Nikolaos
%A Lopez, David
%A Vinogradov, Evgenii
%A Oestges, Claude
%T Experimental performance evaluation of a 5G spectrum sharing scenario based on field-measured channels
%X In this paper, an experimental performance evaluation is carried out within a communication scenario that features two of the key enablers of 5G: (i) the use of post-OFDM modulations and (ii) an efficient use of the spectrum via spectrum sharing. The experimental lab set-up has been assembled so as to operate in conditions as realistic as possible via the actual realtime implementation of the involved transceivers and also via the utilization of propagation channels which have been recorded in a field measurement campaign and which are loaded in a channel emulator that also operates in real-time. The experimental results show that co-existence in a shared spectrum scenario is possible and that the performance degradation is kept at a low level as long as one of the two users is making use of spectrally agile post- OFDM modulations such as filterbank multicarrier (FBMC).
%K ICTM:COMM
%G Anglais
%B Proceedings 26th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)
%D 2015
%U Handle: http://hdl.handle.net/2078.1/165025
%R 10.1109/PIMRC.2015.7343417
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, I.
%A Sacchi, C.
%A Vandendorpe, Luc
%T Green BICM-OFDM based cooperative communications using bargaining game algorithm
%X In this paper, a relay-based energy-efficient cooperative communication strategy is proposed, under the hypothesis that the relay transmits with power drawn from energy-harvesting (EH) sources. Assuming a deterministic EH model under which the harvested amount of energy is known prior to transmission, a spectrally efficient adaptive Bit-Interleaved Coded (BIC) OFDM modulation scheme has been investigated. To guarantee the successful reception of a packet, Automatic Repeat Request (ARQ) protocol has been adopted. Assuming a long term static channel, the expected goodput (EGP) metric is used as cost function to be optimized. The most significant step-ahead of the proposed approach with respect to state-of-the-art is to increase the cooperation gain by using a bargaining game algorithm. Since most renewable sources are highly intermittent, they can induce significant fluctuation on the available power. The bargaining game algorithm takes into account the energy status of the relay and helps the source node to decide whether to cooperate or not with the relay. Achieved simulation results show that the bargaining game algorithm actually helps the nodes to select the right strategy, with a substantial goodput improvement, in particular when the energy availability of relay becomes intermittent due to the harvesting.
%K ICTM:SIGN
%K ICTM:COMM
%G Anglais
%B 2015 IEEE Aerospace Conference, AERO 2015
%D 2015
%U Handle: http://hdl.handle.net/2078.1/165139
%R 10.1109/AERO.2015.7118895
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gueuning, Quentin
%A Craeye, Christophe
%A Oestges, Claude
%T Inhomogeneous plane-wave spectrum basedphysical optics
%X The Physical Optics aperture radia- tion is decomposed into an inhomogeneous plane- wave spectrum, for which a sub-nyquist sampling is achieved, despite a 2-digits accuracy. Validation with a Hertzian dipole and observations are made for large planar surfaces. The Spectral Physical Optics (SPO) seems particularly well-suited for multiple in- teractions between large facets in complex scattering environnements.
%K ICTEAM:COMM
%G Anglais
%B Proceedings International Conference on Electromagnetics in Advanced Applications
%I IEEE
%D 2015
%U Handle: http://hdl.handle.net/2078.1/162278
%R 10.1109/ICEAA.2015.7297361
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Castel, Thijs
%A Lemey, Sam
%A Agneessens, Sam
%A Van Torre, Patrick
%A Rogier, Hendrik
%A Oestges, Claude
%T LTE as a potential standard for public safety indoor body-to-body networks
%X In this paper, a wideband indoor body-to-body communication channel is characterized and analyzed into detail by means of the RMS delay spread and the 50% correlation bandwidth. These body-to-body channel parameters are calculated based on high-resolution power delay profiles, directly provided by the Elektrobit channel sounder, and are further analyzed using a ray tracing algorithm. We have replicated a real-life rescue operation, performed by two firefighters as part of the Rapid Intervention Team searching for potential victims, operating at the same floor of an office block. Both firefighters, who were simultaneously moving around in the vicinity of each other, were equipped with two cavity-backed Substrate Integrated Waveguide textile antennas unobtrusively integrated in the front and back section of their jackets, allowing us to analyze four independent body-to-body links. Furthermore, we prove that the Long Term Evolution (LTE) and, by extension, the LTE - Device to Device (LTE-D2D) standard is compatible with this indoor body-to-body channel. This could provide high data rate indoor communication between rescuers, enabling multimedia broadcast and realtime communication of on-body sensor data in public safety networks.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT)
%D 2015
%U Handle: http://hdl.handle.net/2078.1/179940
%R 10.1109/SCVT.2015.7374220
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Navaux, Mathieu
%A Rottenberg, François
%A Louveaux, Jérôme
%T Phase Synchronisation for FBMC/OQAM Fiber-Optic Transmissions
%X In this paper, we investigate two phase synchronisation schemes for FBMC/OQAM (lterbank based multicarriers) in ber-optic transmissions. We start by investigating pilotbased phase synchronisation, using the so-called auxiliary pilot method [2] consisting in using the pilot's neighbour symbol to compensate for the imaginary intersymbol interference. We derive the maximum likelihood estimator based on the observation of the pilots and analyse its performance. In the second part, taking advantage of the particular shape of the received constellation, a semi-blind channel estimation scheme presented in [3] is adapted to the phase synchronisation issue. It uses the spatial-sign covariance matrix to identify the main variance axis and infer the rotation of the constellation. Both methods are compared and their performance is analyzed by simulations.
%G Anglais
%B Proceedings of the 36th Symposium on Information Theory in the Benelux
%D 2015
%U Handle: http://hdl.handle.net/2078.1/168450
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Degraux, Kévin
%A Jacques, Laurent
%A Horlin, François
%A Louveaux, Jérôme
%T Pilots allocation for sparse channel estimation in multicarrier systems
%X N/A
%G Anglais
%B Proceedings of the Symposium on Information Theory in the Benelux, (Brussels, Belgium)
%D 2015
%U Handle: http://hdl.handle.net/2078.1/168001
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Medjahdi, Yahia
%A Kofidis, Eleftherios
%A Louveaux, Jérôme
%T Preamble-based Channel Estimation in Asynchronous FBMC-OQAM Distributed MIMO Systems
%X This paper investigates downlink channel estimation in a distributed MIMO context employing Filter Bank-based Multi-Carrier Offset QAM (FBMC-OQAM) modulation. Training preambles are constructed based on two different subcarriers assignment schemes (SAS), with the aim of freeing the estimation procedure from the effects of the multi-stream interference (MSI). The Linear Minimum Mean Squared Error (LMMSE) estimator is considered for computing estimates of the channel frequency responses over the entire frequency band and shown to be robust to ill-conditioning associated with the SAS. The application of the different SAS to FBMC-OQAM is evaluated via simulations in an unsynchronized scenario. The performances are compared with the corresponding fully synchronized CP-OFDM scenario. The results demonstrate the robustness of FBMC-OQAM to asynchronism and reveal the advantages of each SAS in various situations.
%G Anglais
%B Proceedings of The Twelfth International Symposium on Wireless Communication Systems
%D 2015
%U Handle: http://hdl.handle.net/2078.1/168451
%R 10.1109/ISWCS.2015.7454409
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Castel, Thijs
%A Lemey, Sam
%A Agneessens, Sam
%A Van Torre, Patrick
%A Rogier, Hendrik
%A Oestges, Claude
%T Reliable communication between rescuers during interventions using textile antenna systems
%X The safety of on-duty firefighters in indoor environments could be increased by ensuring reliable, high-data rate communication in potentially life-threatening situations. This increases their situational awareness, strengthens their decision making and decreases response time by ensuring efficient indoor communication of sensor data, biometric data, pictures or videos. Therefore, a real-life rescue operation was replicated by means of two simultaneously moving firefighters in an office environment. These wideband channel sounder measurements were performed at 3.6 GHz with 80 MHz bandwidth. Four Ultra-Wideband Substrate Integrated Waveguide cavity-backed slot textile antennas were integrated in the front, back, left shoulder and right shoulder sections of the firefighters' jackets, providing up to 4×4 MIMO communication. For this indoor environment, we extract the pertinent OFDM parameters using the RMS delay spread and 50% correlation bandwidth of the sixteen individual SISO channels. Furthermore, we calculate the potential SISO-, 2×2 MIMO- and 4×4 MIMO-OFDM capacities and corresponding data rates. Finally, we show that the 4×4 MIMO setup is more energy efficient and increases both the link reliability and link quality.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE 20th International Workshop on Computer Aided Modelling and Design of Communication Links and Networks (CAMAD)
%D 2015
%U Handle: http://hdl.handle.net/2078.1/179937
%R 10.1109/CAMAD.2015.7390495
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SSH/IACS - Institute of Analysis of Change in Contemporary and Historical Societies
%A Van Hecke, J.
%A Del Fiorentino, P.
%A Giannetti, F.
%A Lottici, V.
%A Vandendorpe, Luc
%A Moeneclaey, M.
%T Resource allocation for multicarrier cooperative cognitive radio networks with imperfect channel state information
%X In this paper we consider a decode-and-forward cooperative network, which is active in the same bandwidth as a primary user network. The cooperative or secondary user network applies a dynamic resource allocation algorithm to maximize its own performance while limiting the interference caused at the primary user receivers. The main contribution of this paper is the proposition of a new accurate approximation for the outage probability, which takes into account that the channel state information available at the transmitter is imperfect and outdated. The accuracy of the approximation and the performance of the resource allocation scheme are validated through numerical simulations. © 2014 IEEE.
%K Cognitive Radio
%K Cooperative Communications
%K Decode-and-forward
%K Multicarrier
%K ICTM:SIGN
%K ICTM:COMM
%G Anglais
%B Proceedings IEEE ICC 2015
%D 2015
%U Handle: http://hdl.handle.net/2078.1/167339
%R 10.1109/ICC.2015.7248520
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A He, Ruisi
%A Renaudin, Olivier
%A Kolmonen, Veli-Mati
%A Haneda, Katsuyuki
%A Zhong, Zhangdui
%A Ai, Bo
%A Oestges, Claude
%T Statistical Characterization of Dynamic Multi-Path Components for Vehicle-to-Vehicle Radio Channels
%X To statistically model time-variant vehicle-to-vehicle (V2V) channels, the dynamic multi-path components (MPCs) are characterized based on suburban measurements conducted at 5.3 GHz. The correlation matrix distance (CMD) is used to determine the size of local wide-sense stationary (WSS) region. Within each WSS time window, MPCs are extracted using wideband spatial spectrum of Bartlett beamformer. A MPC distance (MCD)-based tracking algorithm is used to identify the "birth" and "death" of MPCs over different WSS regions, and the lifetime of MPC is modeled with a truncated Gaussian distribution. Distributions of number of MPCs and their positions are statistically modeled. The MPC characterization considers both angular and delay domain properties as well as the dynamic evolution of MPCs over different WSS regions. The results shows insight into the dynamic behaviors of MPCs in V2V environments, and is useful for the scatterer modeling in the geometry-based stochastic channel modeling.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE 81st Vehicular Technology Conference (VTC Spring)
%I IEEE
%D 2015
%U Handle: http://hdl.handle.net/2078.1/167802
%R 10.1109/VTCSpring.2015.7146108
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%A Khan, Nizabat
%A Mani, Francesco
%A Prieto-Cerdeira, Roberto
%T A Geometry-Based Physical-Statistical Model of Land Mobile Satellite Channels in Urban Environments
%X The land mobile satellite radio channel between a satellite and a mobile terminal in a typical built-up environment is calculated via a constrained geometry-based model, i.e. replacing physical building facades by clusters of equivalent point scatterers. The properties of these scatterers (in terms of power density and angular spreading) are derived from the application of a physical ray-tracing tool including specular as well as dense multipaths in a canonical street canyon scenario. The proposed approach also incorporates a polarimetric model of diffuse multipath scattering.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 8th European Conference on Antennas and Propagation
%D 2014
%U Handle: http://hdl.handle.net/2078.1/143111
%R 10.1109/EuCAP.2014.6902264
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gan, Mingming
%A Meissner, Paul
%A Mani, Francesco
%A Leitinger, Erik
%A Fröhle, Markus
%A Oestges, Claude
%T Calibration of Indoor UWB Sub-band Divided Ray Tracing Using Multiobjective Simulated Annealing
%X Sub-band divided ray tracing (RT) has been widely used to reproduce as reliably as possible the ultra-wideband (UWB) radio wave propagation channel in realistic indoor envi- ronments. However, its accuracy is strictly limited by the available description of the environment. Moreover, its computational complexity scales with the number of selected subbands and the number of propagation paths. In the present work, our RT tool considers not only deterministic propagation paths but also dif- fuse scattering components. Based on a low-complexity sub-band divided RT implementation, we propose a calibration method for indoor UWB sub-band divided RT. The method estimates the optimal material parameters, including the dielectric parameters and the scattering parameters, using channel measurements and multiobjective simulated annealing (MOSA). This calibration can improve the accuracy of sub-band divided RT in terms of the power delay profile (PDP) and the root mean square (RMS) delay spread for all test locations including those not considered by the calibration. A measurement campaign is used to verify the calibration technique.
%K ICTM:COMM
%G Anglais
%B Proceedings 2014 IEEE International Conference on Communications (ICC)
%I IEEE
%D 2014
%U Handle: http://hdl.handle.net/2078.1/165027
%R 10.1109/ICC.2014.6884087
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%A Sanguinetti, L.
%A Bacci, G.
%T Distributed energy-efficient power optimization for relay-aided heterogeneous networks
%X This paper presents an energy-efficient power allocation for relay-aided heterogeneous networks subject to coupling convex constraints, that make the problem at hand a generalized Nash equilibrium problem. The solution to the resource allocation problem is derived using a sequential penalty approach based on the advanced theory of quasi variational inequality, which allows the network to converge to its generalized Nash equilibrium in a distributed manner. The main feature of the proposed approach is its decomposability, which leads to a two-layer distributed algorithm with provable convergence. © 2014 IFIP.
%K Game theory
%K Power Optimization
%K Quasi variational inequalities
%K Resource allocation problem
%K Energy efficiency
%K Heterogeneous networks
%K Variational techniques
%K Wireless networks
%K Convex constraints
%K Energy efficient
%K Generalized Nash equilibrium
%K Generalized Nash equilibrium problems
%K Power allocations
%K ICTEAM
%K ICTEAM:SIGN
%K ICTEAM:COMM
%G Anglais
%B Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), 2014 12th International Symposium on
%D 2014
%U Handle: http://hdl.handle.net/2078.1/150833
%R 10.1109/WIOPT.2014.6850347
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Rottenberg, François
%A Louveaux, Jérôme
%T Dominant eigenmode transmission in MIMO FBMC for frequency-selective channels
%X In this paper, we consider a MIMO transmission using FBMC (filter-bank based multicarrier) modulation where channel state information (CSI) is assumed to be available at the transmitter. The so-called dominant eigenmode transmission (DET) scheme is investigated. This technique uses a joint beamforming scheme to transmit a single stream of data and can extract both full spatial diversity and a high array gain. It has already been shown that it can be applied to the FBMC modulation if the channel is not too selective in frequency. The paper then aims at comparing the performance of the DET technique with FBMC (more precisely the OFDM/OQAM version) and OFDM respectively, in a variety of channels including highly frequency selective channels. It is known that FBMC outperforms OFDM in mildly selective channels thanks to its better energy-efficiency. The paper investigates the effect of higher frequency selectivity on the DET technique both in the case of FBMC and OFDM. It is shown that FBMC slightly suffers from inter-carrier and inter-symbol interference while OFDM robustness heavily depends on the cyclic prefix length. To improve the FBMC behavior against channel selectivity, a low complexity per-subcarrier equalizer is designed based on the frequency sampling (FS) technique. The paper analyzes the trade-off between energy-efficiency and robustness against frequency selective channels that the two modulation techniques offer.
%G Anglais
%B Proceedings of the 35th WIC Symposium on Information Theory in the Benelux
%D 2014
%U Handle: http://hdl.handle.net/2078.1/156940
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Hanssens, Brecht
%A Marinez-Ingles, Maria-Teresa
%A Bamba, Aliou
%A Tanghe, Emmeric
%A Molina-Garcia-Pardo, Jose-Maria
%A Gaillot, Davy
%A Liénard, Martine
%A Oestges, Claude
%T Estimation of Room Electromagnetics ReverberationTime for Ultra-Wideband Indoor Channels
%X In this work, an estimation of the reverberation time for Ultra-Wideband indoor communication is presented ranging from 2 to 10 GHz. Channel sounding measurements were performed in an indoor environment with a network analyzer and virtual arrays. The concept of a reverberation time is known from the theory of Room Electromagnetics, and can be calculated from the decay rate of the measured power delay profiles. It was found that this reverberation time depends on the used window function in order to shape the frequency-response measurements, and that it decreases with increasing frequency due to path loss.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 8th European Conference on Antennas and Propagation
%D 2014
%U Handle: http://hdl.handle.net/2078.1/143112
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mallat, Achraf
%A Vandendorpe, Luc
%T Joint estimation of the time delay and the clock drift and offset using UWB signals
%X We consider two transceivers, the first with perfect clock and the second with imperfect clock. We investigate the joint estimation of the delay between the transceivers and the offset and the drift of the imperfect clock. We propose a protocol for the synchronization of the clocks. We derive some empirical estimators for the delay, the offset and the drift, and compute the Cramer-Rao lower bounds and the joint maximum likelihood estimator of the delay and the drift. We study the impact of the protocol parameters and the time-of-arrival estimation variance on the achieved performances. We validate some theoretical results by simulation. © 2014 IEEE.
%K ICTEAM
%K SIGN
%K COMM
%G Anglais
%B Communications (ICC), 2014 IEEE International Conference on
%I IEEE
%D 2014
%U Handle: http://hdl.handle.net/2078.1/152283
%R 10.1109/ICC.2014.6884192
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gan, Mingming
%A Meissner, Paul
%A Mani, Francesco
%A Leitinger, Erik
%A Fröhle, Markus
%A Oestges, Claude
%T Low-complexity sub-band divided ray tracing for UWB indoor channels
%X Ray tracing has been extensively used to simulate indoor channel characteristics. For an ultra-wideband system, the channel characteristics vary significantly over the entire bandwidth. To cope with this, sub-band divided RT has been proposed by dividing the frequency of interest into multiple subbands and superposing the RT results at the individual center frequency of each subband. Thus, the computational complexity is directly proportional to the number of subbands. In this paper, we propose a mathematical method to significantly reduce the computational complexity of the sub-band divided RT, making it almost independent of the number of subbands. It is important to note that, based on our approach, not only the determination of the rays reaching a give location is made only once, but also the electromagnetic calculation of the received signal is not needed to perform repeatedly. The accuracy of low-complexity subband divided RT algorithm is verified through a measurement campaign.
%K ICTM:COMM
%G Anglais
%B Proceedings IEEE Wireless Communications and Networking Conference (WCNC)
%I IEEE
%D 2014
%U Handle: http://hdl.handle.net/2078.1/165026
%R 10.1109/WCNC.2014.6951985
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vinogradov, Evgenii
%A Joseph, Wout
%A Oestges, Claude
%T Modeling and Simulation of Fast Fading Channels in Indoor Peer-to-Peer Scenarios
%X Traditional cellular solutions are coming under increasing pressure from wireless peer-to-peer (P2P) systems. The growing interest in wireless indoor communication systems has resulted in many investigations on the characteristics of indoor radio propagation channels. In this paper, we investigate narrowband indoor distributed channels based on an experimental campaign in an office environment. We evaluate the fast fading statistics using the second-order scattering fading (SOSF) distribution. It turns out from the measurements that the fading statistics change over time. An approach to model these effects is proposed.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 8th European Conference on Antennas and Propagation
%D 2014
%U Handle: http://hdl.handle.net/2078.1/143113
%R 10.1109/EuCAP.2014.6901784
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A He, Ruisi
%A Renaudin, Olivier
%A Kolmonen, Veli-Matti
%A Haneda, Katsuyuki
%A Zhong, Zhangdui
%A Ai, Bo
%A Oestges, Claude
%T Non-stationarity Characterization for Vehicle-to-vehicle Channels Using Correlation Matrix Distance and Shadow Fading Correlation
%X Vehicle-to-Vehicle (V2V) radio channels have been considered as non-stationary due to the dynamic scatterers in V2V environments. To characterize its stationarity is of great importance as it determines the time-variant V2V channel statistics. Therefore, we analyze the non-stationarity of V2V radio channels using two metrics: the correlation matrix distance (CMD) and the shadow fading correlation. The analysis is based on the measurements conducted in a suburban area of Finland at 5.3 GHz. We use the Aalto channel sounder and a 30 £ 4 MIMO system. The power delay pro¯le (PDP), CMD, and shadowing are estimated from the measured channel impulse responses. The equivalent stationarity distance is found to be around 6 m, and it is observed that regions with large delay spreads correspond to smaller stationarity regions. The shadow fading auto-correlation coe±cient is found to follow an exponential decay model and the decorrelation distance is considered as the shadowing-based equivalent stationarity distance. Based on the comparison of the equivalent stationarity distances estimated by the two metrics, it is found that the CMD metric is more sensitive to the changes of direction-of-arrival/departure, whereas the shadowing metric takes only into account the power variations over time. We also note that the estimation of shadowing metric is close to the results from CMD. This shows that the shadow correlation can also be used to characterize the non-stationarity of radio channels.
%G Anglais
%B Proceedings of PIERS 2014 : Progress In Electromagnetics Research Symposium
%I The Electromagnetics Academy
%C (United States) Cambridge, MA
%D 2014
%S PIERS Proceedings
%@ 1559-9450 (ISSN)
%U Handle: http://hdl.handle.net/2078.1/172726
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Medjahdi, Yahia
%A Dziri, A.
%A Louveaux, Jérôme
%T On the performance of FBMC-based AF and DF Multiple Access Relay Networks
%X We investigate the performance of Filter Bank Multi-Carrier (FBMC)-based dual-hop Amplify-and-Forward (AF) and static Decode-and-Forward (DF) in the context of Multiple access relay networks. We show that, in the context of Professional Mobile Radio (PMR) communications and their implementation constraints, AF protocol is more suitable than DF one. In fact, the former protocol requires low complexity and just a single receive antenna at the relay node rather than two for the latter. Furthermore, we show that AF and DF protocols present almost similar BER performances in the case of a relay with a single Transmit antenna for both ZF and MMSE equalizers.
%G Anglais
%B Proceedings European Conference on Networks and Communications (EuCNC)
%D 2014
%U Handle: http://hdl.handle.net/2078.1/156939
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Pasquero, Oudomsack Pierre
%A Rosini, Ramona
%A D'Errico, Raffaele
%A Oestges, Claude
%T On-Body Channel Correlation in Various Walking Scenarios
%X To investigate on-body channel space-time correlation characteristics in various walking scenarios, we analyze the correlation properties at 4.2 GHz between two on-body radio links with a transmitter on the heart and receivers on both hands. For that purpose, two different measurement campaigns are exploited. The results show that, depending on the walking scenario, the space-time correlation characteristics can vary from very stationary to not stationary at all. More exactly, the stationarity cases correspond to the scenarios where the subjects walk uniformly and regularly along a straight line with periodic arm swings, whereas the non-stationary behavior arises from random trajectories and irregular arm swings.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 8th European Conference on Antennas and Propagation
%D 2014
%U Handle: http://hdl.handle.net/2078.1/143114
%R 10.1109/EuCAP.2014.6901893
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Medjahdi, Yahia
%A Amara, Mustapha
%A Louveaux, Jérôme
%T SINR tight lower bound for asynchronous OFDM-based multiple-access networks
%X Interference modelling is an important problem necessary to design and deploy wireless communication systems. Orthogonal frequency division multiplexing (OFDM) is presented as the access technique to be used for future communication systems. Therefore, it is crucial to define a quick and reliable way of estimating signal to interference plus noise ratio (SINR) for multicarrier systems. The most used approach is based on the power spectral density where the out-of-band radiation of the interfering signal is computed. In this paper, we show the inaccuracy of this technique and evaluate its deviation compared to the exact value. We also derive tight lower bound expression for the SINR evaluation. We finally validate the expression through simulation results.
%K Cognitive radio
%K OFDM
%K Spectrum coexistence
%G Anglais
%B Proc. 2014 11th International Symposium on Wireless Communications Systems (ISWCS)
%D 2014
%U Handle: http://hdl.handle.net/2078.1/152252
%R 10.1109/ISWCS.2014.6933455
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Bogale, Tadilo Endeshaw
%A Vandendorpe, Luc
%A Le, L.B.
%T Sensing throughput tradeoff for cognitive radio networks with noise variance uncertainty
%X This paper proposes novel spectrum sensing al-gorithm, and examines the sensing throughput tradeoff for cognitive radio (CR) networks under noise variance uncertainty. It is assumed that there are one white sub-band, and one target sub-band which is either white or non-white. Under this assumption, first we propose a novel generalized energy detector (GED) for examining the target sub-band by exploiting the noise information of the white sub-band, then, we study the tradeoff between the sensing time and achievable throughput of the CR network. To study this tradeoff, we consider the sensing time optimization for maximizing the throughput of the CR network while appropriately protecting the primary network. The sensing time is optimized by utilizing the derived detection and false alarm probabilities of the GED. The proposed GED does not suffer from signal to noise ratio (SNR) wall (i.e., robust against noise variance uncertainty) and outperforms the existing signal detectors. Moreover, the relationship between the proposed GED and conventional energy detector (CED) is quantified analytically. We show that the optimal sensing times with perfect and imperfect noise variances are not the same. In particular, when the frame duration is 2s, SNR= -20dB, -20dB and each of the bandwidths of the white and target sub-bands is 6MHz, the optimal sensing times are 28.5ms and 50.6ms with perfect and imperfect noise variances, respectively. © 2014 ICST.
%K Cognitiveradio
%K Achievable throughputs
%K Cognitive radio network
%K False alarm probability
%K Noise information
%K Noise variance
%K Sensing-throughput tradeoffs
%K SNR walls
%K Spectrum sensing
%K Throughput
%K Noise variance uncertainty
%K Sensing Throughput tradeoff
%K SNR wall
%K Spectrum sensing
%K Cognitive radio
%K Signal detection
%K Signal to noise ratio
%K Wireless networks
%K ICTEAM
%K ICTEAM:SIGN
%K ICTEAM:COMM
%G Anglais
%B Proceedings of the 2014 9th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2014
%D 2014
%U Handle: http://hdl.handle.net/2078.1/150835
%R 10.4108/icst.crowncom.2014.255811
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Bogale, T.E.
%A Vandendorpe, Luc
%T USRP implementation of max-min SNR signal energy based spectrum sensing algorithms for cognitive radio networks
%X This paper presents the Universal Software Radio Peripheral (USRP) experimental results of the Max-Min signal to noise ratio (SNR) Signal Energy based Spectrum Sensing Algorithms for Cognitive Radio Networks which is recently proposed in [1]. Extensive experiments are performed for different set of parameters. In particular, the effects of SNR, number of samples and roll-off factor on the detection performances of the latter algorithms are examined briefly. We have observed that the experimental results fit well with those of the theory. We also confirm that these algorithms are indeed robust against carrier frequency offset, symbol timing offset and noise variance uncertainty. © 2014 IEEE.
%K ICTEAM
%K SIGN
%K COMM
%K ICTEAM
%K SIGN
%K COMM
%G Anglais
%B IEEE Proceedings Communications (ICC), 2014 IEEE International Conference on
%D 2014
%U Handle: http://hdl.handle.net/2078.1/152282
%R 10.1109/ICC.2014.6883530
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gusi Amigo, Adria
%A Closas, P.
%A Mallat, Achraf
%A Vandendorpe, Luc
%T Ziv-Zakai lower bound for UWB based TOA estimation with unknown interference
%X This paper derives the Ziv-Zakai lower bound (ZZLB) for the time of arrival (TOA) estimation in the presence of one interfering pulse from which no a priori knowledge is available. The bound is obtained by including the interference in the system model but only the transmitted pulse as a candidate for the likelihood ratio (LR) test. A compact ZZLB expression that depends on the time delay and amplitude of the interference is obtained. We compare the performance of the first path maximum likelihood estimation (MLE) with the bound as a function of the relative distance between the first path and the interfering path. © 2014 IEEE.
%K Interference
%K Time of arrival estimation
%K Ultra wideband communication
%K Ziv-Zakai lower bound
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Acoustics, Speech and Signal Processing (ICASSP), 2014 IEEE International Conference on
%I IEEE
%D 2014
%U Handle: http://hdl.handle.net/2078.1/150776
%R 10.1109/ICASSP.2014.6854857
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Andreotti, R.
%A Lottici, V.
%A Giannetti, F.
%A Stupia, Ivan
%A Vandendorpe, Luc
%T A game theoretical approach for reliable packet transmission in noncooperative BIC-OFDM systems
%X In this work, we investigate the power allocation (PA) problem aimed at minimizing the users' packet error rate (PER) over a noncooperative link, i.e., a link where the set of users, employing packet-oriented bit-interleaved coded (BIC) orthogonal frequency division multiplexing (OFDM) systems, compete for the same bandwidth. For these kind of systems, the PER is not available in closed-form, but a very efficient solution is offered by the effective SNR mapping (ESM) technique. This method allows each user to evaluate a single scalar value, the effective SNR (ESNR), accounting for all the SNIRs experienced over the active subcarriers, and to univocally map it into a PER value. Thus, in order to derive a decentralized strategy allowing each user to minimize its own PER, the problem is described as a strategic game, called min-PER game, with the set of player, utilities and strategies represented by the competitive users, the ESNRs and the set of feasible power allocations, respectively. We will show both the existence of at least one Nash Equilibrium (NE) for the min-PER game and its equivalence with a Nonlinear Variational Inequality (NVI) problem. Finally, relying on the theory of contraction mappings, we will derive a distributed algorithm to reach the NE of the game.
%G Anglais
%B Communications (ICC), 2013 IEEE International Conference on
%D 2013
%U Handle: http://hdl.handle.net/2078.1/138688
%R 10.1109/ICC.2013.6655536
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%T A generalized Nash game for energy efficiency optimization : a quasi variational inequality approach
%X This paper presents the Nash equilibrium problem for a multipoint-to-multipoint network whose nodes aim at maxi- mizing their energy efficiency (EE). The equilibrium problem is reformulated as a max-rate equilibrium problem with cou- pling among the strategy sets of the players. Unfortunately, the analysis of this kind of games can not be addressed us- ing traditional theoretical tools. To cope with this challenge, the equilibrium problem is formulated as a quasi-variational inequality for which existence results are given. This formu- lation provides us with all the mathematical tools necessary to devise novel distributed algorithms.
%G Anglais
%B 21st European Signal Processing Conference, EUSIPCO 2013
%D 2013
%U Handle: http://hdl.handle.net/2078.1/138876
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gan, Mingming
%A Mani, Francesco
%A Kaltenberger, Florian
%A Oestges, Claude
%A Zemen, Thomas
%T A ray tracing algorithm using the discrete prolate spheroidal subspace
%X Ray tracing (RT) is an accurate propagation prediction tool that has been widely used to simulate channel characteristics in indoor environments. To date, the developed RT tool includes not only specular reflection, penetration through dielectric blocks and diffraction, but also diffuse scattering mechanisms. The accuracy, provided by a detailed modeling of the environment, comes at the cost of a high computational complexity, which directly scales with the number of propagation paths considered. We are interested in simulating the radio propagation conditions for a mobile terminal, communicating in a frame based communication system indoors with several fixed nodes. This communication shall be used to obtain the position of the mobile terminal in indoor scenario. Therefore, the correlated temporal and spatial evolution of the channel impulse response is of utmost concern. In this paper, we propose a method to significantly reduce the computational complexity of RT by using a projection of all propagation paths on a subspace spanned by two-dimensional discrete prolate spheroidal (DPS) sequences. With this method the computational complexity can be reduced by more than one order of magnitude for indoor scenarios. The accuracy of our low-complexity DPS subspace based RT algorithm is verified by numeric simulations.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Communications
%D 2013
%U Handle: http://hdl.handle.net/2078.1/134355
%R 10.1109/ICC.2013.6655505
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vitucci, Enrico Maria
%A Mani, Francesco
%A Oestges, Claude
%A Degli-Esposti, Vittorio
%T Analysis and modeling of the polarization characteristics of diffusescattering in indoor and outdoor radio propagation
%X The polarimetric properties of the radio channel, with particular reference to the Dense Multipath Components (DMC), are analyzed in the present work for different types of outdoor and indoor environments, with the aid of measurements and Ray Tracing (RT) simulations. A heuristic Diffuse Scattering model, suitable to be embedded in RT tools, is properly tuned and parameterized to reproduce the cross-polar discrimination (XPD) characteristics of the DMC extracted from measurement data in the above mentioned scenarios.
%K ICTEAM:COMM
%G Anglais
%B Proceedings ICECOM
%D 2013
%U Handle: http://hdl.handle.net/2078.1/135978
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A El Soussi, Mohieddine
%A zaidi, Abdellatif
%A Vandendorpe, Luc
%T Compress-and-forward on a multiaccess relay channel with computation at the receiver
%X We study a system in which two sources communicate with a destination with the help of a half-duplex relay. We consider a decoding strategy, based on the compute-and-forward strategy, in which the destination decodes two integer-valued linear combinations that relate the transmitted codewords. In this strategy, the relay compresses its observation using Wyner-Ziv compression and then forwards it to the destination. The destination appropriately combines what it gets from the direct transmission and the relay. Then, using this combination, it computes two integer-valued linear combinations. We discuss the encoding/decoding strategy, and evaluate the achievable sum-rate. Next, we consider the problem of allocating the powers and selecting the integer-valued coefficients of the recovered linear combinations in order to maximize the sum-rate. For the model under consideration, the optimization problem is NP hard. We propose an iterative algorithm to solve this problem using coordinate descent method. The results are illustrated through some numerical examples.
%G Anglais
%B IEEE International Conference on Communications (ICC)
%D 2013
%U Handle: http://hdl.handle.net/2078.1/137709
%R 10.1109/ICC.2013.6655436
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Liu, Lingfeng
%A De Doncker, Philippe
%A Oestges, Claude
%T First- and Second-Order Statistics of On-Body Propagation Channels
%X On-body channel dynamics are primarily affected by body motions, which not only cause dynamic scattering conditions but also modify the geometry of links over time. We experimentally investigate the Doppler spectra of narrowband on-body channels at 2.45 GHz in both anechoic and indoor environments. The body dynamics resulting from the motion are shown to directly affect the Doppler spectrum. An empirical model is proposed to describe the global and/or local Doppler spreads. The fit of a 3-cylinder-based physical model accounting for the arm swinging is also evaluated.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE 77th Vehicular Technology Conference Spring
%D 2013
%U Handle: http://hdl.handle.net/2078.1/130656
%R 10.1109/VTCSpring.2013.6692569
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Louveaux, Jérôme
%A Bourdoux, André
%A Horlin, François
%T Low feedback downlink MIMO channel estimation for distributed FBMC systems using SNR measurements
%X In this paper, we present a new method to estimate the MIMO channel in a distributed MIMO system using FBMC modulation (Filter Bank based Multicarrier). As opposed to previously presented methods, it is not based on the existence of pilots and therefore avoids the necessity of auxiliary pilots or similar methods. Besides, it requires a very low amount of feedback. Only the SNR observed by the different users need to be fed back periodically. It is intended for the estimation of the downlink MIMO channel in a distributed beamforming system where the basestations can cooperate to some extent. It is based on the concept of adding small, controlled, perturbations to the transmitted signals and observing the related changes to the SNR at the receivers. It is shown in this paper that, based on a limited amount of SNR measurements from the receivers, it is possible to accurately estimate the MIMO channels, both in amplitude and phase. It is also shown that the proposed method exhibits the best performance in a tracking mode.
%G Anglais
%B Proceedings of the 10th International Symposium on Wireless Communication Systems (ISWCS 2013)
%D 2013
%U Handle: http://hdl.handle.net/2078.1/137047
%* peer-reviewed
%0 Conference Paper
%9 Conférence invitée / Keynote
%A Oestges, Claude
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T Multi-Dimensional Channel Sounding: Recent Results and Challenges
%D 2013
%X This coomunication explores the multiple dimensions of wireless channels that are currently under investigation with regard to emerging communication networks. In a first part, various channel sounding techniques will be analyzed for wireless scenarios involving more than link. We detail a number of recent existing experimental results, in particular those achieved within COST 2100 Action. These results will cover both outdoor and indoor environments and provide an overview of the COST 2100 multi-dimensional channel model. Finally, remaining challenges are highlighted.
%K ICTEAM:COMM
%G Anglais
%B Wireless Communications Symposium
%C Vina del Mar
%8 du 07/11/2013 au 08/11/2013
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078.1/136095
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Meissner, Paul
%A Gan, Mingming
%A Mani, Francesco
%A Leitinger, Erik
%A Oestges, Claude
%T On the use of ray tracing for performance prediction of UWB indoor localization systems
%X The most important factors impairing the performance of radio-based indoor localization systems are propagation effects like strong reflections or diffuse scattering. To the full extent, these effects can be captured only by time-consuming measurement campaigns. Ray tracing (RT) offers the possibility to predict the radio channel for a certain environment, avoiding the need for measurements. However, it is crucial to include all relevant propagation mechanisms in the RT as well as to validate the obtained results. In this paper, we show that sub-band divided RT can yield realistic ultra-wideband channel impulse responses that can be used instead of real measurements. We show this by using the RT results for performance prediction of multipathassisted localization, which depends to a great extent on the above mentioned propagation effects. A previously introduced method to estimate the ratio of the signal energies of deterministically reflected paths to diffuse scattered components is employed on both the RT results and the channel measurements in an indoor environment. This analysis is useful in two ways: first, as this ratio scales the amount of position-related information of deterministic multipath components, it can be used for localization performance prediction; second, this ratio includes two main propagation mechanisms and is thus useful to validate the subband divided RT.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Communications
%D 2013
%U Handle: http://hdl.handle.net/2078.1/134354
%R 10.1109/ICCW.2013.6649203
%* peer-reviewed
%0 Conference Paper
%9 Conférence invitée / Keynote
%A Panahandeh, Ali
%A Oestges, Claude
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T Performance of Polarized Sensing in Real-World Cognitive Radio Scenarios
%D 2013
%X The sensing performance of a cognitive radio system using a tri-polarized antenna at the secondary terminal is investigated in a real-world scenario. The analysis is based on an outdoor-to-indoor measurement campaign, where the secondary network is deployed indoor and senses the signals received from an outdoor primary base-station. By considering a minimum acceptable detection probability of 0.95, the use of diversity increases the range of acceptable sensing up to 18 meters. The minimum acceptable signal-to-noise ratio (SNR) is reduced up to 14 dB. As expected, the best performance is reached with maximum ratio combining. However, the detection performance is only slightly decreased with square law combining (SLC). As an example, for the multi-polarized reception scenario, SLC increases the minimum acceptable SNR by less than 2 dB and decreases the range of acceptable sensing by less than 3 meters. Finally, we show that polarized sensing is a good performance trade-off in realistic scenario where the polarization of the primary transmitter is unknown.
%K ICTEAM:COMM
%G Anglais
%B Journées Scientifiques de l'URSI
%C Paris, France
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078.1/130658
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Martin, Arnaud
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T Precoder optimization for DSL with high crosstalk
%X Next generation DSL systems aim to provide very high data-rates by transmitting at much higher frequencies. Current transmissions go up to 20MHz while transmissions up to 100MHz are considered for G.Fast. At such high frequency ranges, the electro-magnetic coupling between twisted pairs of a binder group, named Crosstalk, becomes very large, sometimes even larger than the direct signal transmitted on the line. Efficient crosstalk precompensation techniques (also called precoding) are thus necessary in order to provide the targeted bit rates. The method exploiting the colocation of the transceivers or receivers in order to cancel the crosstalk is called Vectoring [3]. Various precoding techniques have already been designed for current transmission standards (using a frequency range up to 20-30 Mhz) but all the methods considered up to now use the assumption that Far-End Crosstalk (FEXT) is significantly lower than the signal received by the user. The goal of this paper is to propose and analyze different crosstalk cancellation techniques and compare their efficiency in the special case of very high crosstalk, applicable in the high frequency range.
%K DSL
%K Crosstalk cancellation
%K Precoding
%K ICTEAM
%G Anglais
%B Proceedings Joint WIC/IEEE Symposium on Information Theory and Signal Processing in the Benelux
%D 2013
%U Handle: http://hdl.handle.net/2078.1/130695
%* peer-reviewed
%0 Book Section
%9 Conférence invitée / Keynote
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%T Radio Channel Models for Search-and-Rescue Missions into Collapsed Structures
%X Propagation models in the TETRA/GSM/UMTS bands (from 433 MHz to 1.9 GHz) in partially destroyed buildings are derived, using a number of methods with respect to various collapsed structures. These models are useful in the context of pedestrian radio-localization systems relying on cell phone signals. In addition, the electromagnetic properties of concrete and ferro-concrete materials are experimentally characterized and used in the various models. Simulations show that specific attenuation levels can be very severe, from 10 to 100 dB/m, and increase with frequency. This might seriously limit the detection of victims under more than one meter of ferro-concrete rubbles in the UMTS band. However, localization algorithms based on direction-of-arrival estimation are unlikely to be degraded by multipath spreading.
%K ICTEAM:COMM
%G Anglais
%B Proceedings of 2013 URSI International Symposium on Electromagnetic Theory (EMTS)
%D 2013
%U Handle: http://hdl.handle.net/2078.1/134356
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gusi Amigo, Adria
%A Vandendorpe, Luc
%T Ziv-Zakai Lower Bound for UWB based TOA Estimation with Multiuser Interference
%X The aim of this paper is to derive a Ziv-Zakai lower bound (ZZLB) for the time of arrival (TOA) estimation in single-path (SP) additive white Gaussian noise (AWGN) channels and in the presence of multiuser interference (MUI). Time-hopping pulse position modulated (TH-PPM) ultra-wideband (UWB) signals are considered. Following a classical approach and extending it for the scenario under consideration, we compute the ZZLB by converting the related estimation problem into a binary detection one. To obtain the bit error rate (BER) of the corresponding detection problem, we both consider the exact handling of the MUI and the modeling of the MUI by means of a Gaussian approximation (GA).We compare the performance of the single-user maximum likelihood (ML) TOA estimator with the bounds.
%G Anglais
%B Acoustics, Speech and Signal Processing (ICASSP), 2013 IEEE International Conference on
%I IEEE
%D 2013
%U Handle: http://hdl.handle.net/2078.1/130913
%R 10.1109/ICASSP.2013.6638599
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - Autre
%A Stupia, Ivan
%A Andreotti, Riccardo
%A Lottici, V.
%A Vandendorpe, Luc
%T A consensus approach for cooperative communications in cognitive radio networks
%X In this paper, we investigate a decentralized power allocation (PA) algorithm, i.e., without the need of a fusion center, for a coalition of bit-interleaved coded (BIC) OFDM-based cognitive radio (CR) devices. Taking advantages of a game theoretical description for our problem, it is shown that the reliability of the secondary cooperative link can be remarkably improved through a simple average consensus algorithm keeping the interference produced to the primary users (PUs) under a prescribed threshold. Finally, the performance gain of the proposed PA policy is highlighted comparing it with conventional power allocation algorithms. © 2012 EURASIP.
%K ICTEAM
%K ICTEAM:COMM
%G Anglais
%B 20th European Signal Processing Conference, EUSIPCO 2012
%D 2012
%U Handle: http://hdl.handle.net/2078/118179
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%A Andreotti, R.
%A Lottici, V.
%T A game theoretical approach for coded cooperation in cognitive radio networks
%X In this paper, the authors focus on a game theoretical approach for cooperation in cognitive radio (CR) networks. In particular, an integrated design framework which relies on the effective SNR methodology is proposed. The authors derive a distributed power allocation policy aimed at maximizing the reliability of a cooperative BIC OFDM link wherein pragmatic modulation and coding schemes are considered. More in detail, the cognitive devices adapt their power to enable efficient cooperation and coexistence between cognitive nodes and primary networks. First of all, the gain due to the cooperation protocol is analytically derived, resorting to a simple first order recursive equation that depends on the current channel conditions. Then, after an accurate formalization of the optimization problem, a distributed iterative solution based on a novel algorithm, named Successive Set Reduction, is proposed. In particular, the authors show that : i) the proposed power allocation policy takes into account the cooperative gain through a simple scalar value, named cooperative effective SNR; ii) it is effective in improving the packet error rate performance with respect to other conventional power allocation strategies, thus allowing a better coverage for the secondary network; iii) the convergence of the distributed algorithm has exponential speed and requires only local signaling between secondary users. © 2012 IEEE.
%K Coded cooperation
%K Iterative solutions
%K Modulation and coding schemes
%K Novel algorithm
%K Optimization problems
%K Packet error rates
%K Power allocations
%K Recursive equations
%K Scalar values
%K Secondary networks
%K Theoretical approach
%K Cognitive radio network
%K Algorithms
%K Cognitive radio
%K Signal processing
%K Game theory
%K Conventional power
%K Cooperation protocols
%K Current channel condition
%K Distributed Power-Allocation
%K Effective SNR
%K First order
%K Integrated design framework
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Communications Control and Signal Processing (ISCCSP), 2012 5th International Symposium on
%D 2012
%U Handle: http://hdl.handle.net/2078/116828
%R 10.1109/ISCCSP.2012.6217850
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ ULB - OPERA
%A Panahandeh, Ali
%A Quitin, François
%A Dricot, Jean-Michel
%A Horlin, François
%A Oestges, Claude
%A De Doncker, Philippe
%T A time-variant statistical model for the polarization of received electromagnetic waves in indoor communication channels
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Computing, Networking and Communications
%D 2012
%U Handle: http://hdl.handle.net/2078.1/111399
%R 10.1109/ICCNC.2012.6167424
%* peer-reviewed
%0 Conference Paper
%9 Conférence invitée / Keynote
%A El Soussi, Mohieddine
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute of Information and Communication Technologies, Electronics and Applied Mathematics
%T Amplify-and-Forward on a Multiaccess Relay Channel With Computation at the Receiver
%D 2012
%X We consider a communication system in which two sources communicate with a destination with the help of a common relay. We assume that the relay operates in half-duplex mode; and concentrate on the symmetric-rate case. We study and analyse the performance of a simple strategy in which the relay simply amplifies its output and retransmits it. However, unlike standard amplify-and-forward, the destination recovers the sent messages by computing and inverting two appropriate linear combinations of the sources' messages, obtained using what it gets from the sources and the relay. We discuss the design criteria and establish the sum-rate allowed by this strategy. Also, we consider, and solve, the problem of maximizing the sum-rate by properly optimizing the power values and the integer-valued coefficients of the recovered linear combinations. It should be emphasized that although the coding strategy described in this paper performs only as good as standard amplify-and-forward, it has the advantage of utilizing simpler linear codes; and, so, is more relevant in practical collaborative systems.
%G Anglais
%B International Conference on Network Games, Control and Optimization, Netgcoop
%C Avignon
%8 du 28/11/2012 au 30/11/2012
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078/122991
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gomes de Oliveira Brante, Glauber
%A Souza, R.D.
%A Vandendorpe, Luc
%T Battery-aware energy efficiency of incremental decode-and-forward with relay selection
%X We analyze the energy efficiency of reactive and proactive relay selection algorithms under the incremental decode-and-forward protocol. By taking into account the consumption of the RF circuitry, the transmit power, and a nonlinear model for the battery, we show that a large number of available relays can actually compromise the energy efficiency of the system. Our results show that, depending on the source to destination distance, it may be preferable to consider only a small subset of nodes and select the relay among these nodes. © 2012 IEEE.
%K Battery-aware
%K Decode-and-forward
%K Decode-and-forward protocols
%K Non-linear model
%K Relay selection
%K RF circuitry
%K Transmit power
%K Wireless telecommunication systems
%K Energy efficiency
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Wireless Communications and Networking Conference (WCNC), 2012 IEEE
%D 2012
%U Handle: http://hdl.handle.net/2078/116826
%R 10.1109/WCNC.2012.6213941
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Brah, Félix
%A Dayoub, I.
%A Vandendorpe, Luc
%T Constrained resource allocation for OFDMA cognitive radio networks with primary users activity consideration
%X In this paper, we consider resource allocation for downlink OFDMA-based cognitive radio (CR) networks. Instead of using only channel information, the statistics of the sensing information conditioned on the primary user (PU) activity is also incorporated in the design and the optimization of the resource allocation. The objective is to maximize the ergodic weighted sum-rate under total power constraint and a per subcarrier based interference power constraint to protect primary users. We develop an optimal solution method and propose a closed-form suboptimal solution with a complexity of O(KN) for K users and N subcarriers. Simulation results are provided to compare the performance of this method with other allocation schemes and to illustrate the trade-off between maximized ergodic weighted sum rate and the constraints.
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Wireless Communication Systems (ISWCS), 2012 International Symposium on
%D 2012
%U Handle: http://hdl.handle.net/2078/118189
%R 10.1109/ISWCS.2012.6328471
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Khan, Nizabat
%A Jiang, Tao
%A Grace, David
%A Burr, Alister G.
%A Oestges, Claude
%T Impact of multi-beam antenna amplitude tapering on co-channel interference and backhaul throughput density
%X Multi-beam antennas, combined with aggressive frequency reuse have recently been considered to increase the throughput density in densely deployed cellular networks. However, the latter is limited by Co-Channel Interference (CCI). To mitigate this problem, amplitude tapering in multi-beam antenna scenarios is investigated in this paper. Results show that tapered beams significantly improve the Carrier to Interference Ratio (CIR) from 5 to 8 dB and consequently achieve downlink backhaul throughput density over 0.6 Gbps/km2. An overall throughput density of 1.2 Gbps/km2 is expected when taking both up- and downlinks into account.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 15th International Symposium on Wireless Personal Multimedia Communications
%D 2012
%U Handle: http://hdl.handle.net/2078.1/117982
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%A El Soussi, Mohieddine
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Iterative sum-rate optimization for multiple access relay channels with a compute-and-forward relay
%X We consider a multiple access relay channel (MARC), in which a relay, based on the recently proposed compute-and-forward protocol, helps two transmitters to communicate with a common destination. The relay decodes a linear combination of the received symbols instead of the individual symbols then forwards the new symbol to the destination. The destination recovers two linear equations from the decoded signals. The two equations relate the transmitted symbols with integer coefficients at different computational rates. We propose an iterative algorithm to optimize the integer coefficients and the power allocation at the transmitters alternatively, so that the sum-rate is maximized. In each iteration, the integer coefficients are updated by solving a mixed-integer quadratic programming (MIQP) problem with quadratic constraints, while the power allocation is updated by solving a series of geometric programs using a successive convex approximation method. The simulation results show that the compute-and-forward strategy and the proposed optimization method can offer substantial gain over the standard amplify-and-forward and decode-and-forward protocols for this model.
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B IEEE International Conference on Communications (ICC)
%D 2012
%U Handle: http://hdl.handle.net/2078/118188
%R 10.1109/ICC.2012.6363878
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Bogale, Tadilo Endeshaw
%A Vandendorpe, Luc
%T Multi-cycle cyclostationary based spectrum sensing algorithm for OFDM signals with noise uncertainty in cognitive radio networks
%X This paper proposes a simple multi-cycle cyclostationary based signal detection (spectrum sensing) algorithm for Orthogonal Frequency Division Multiplexed (OFDM) signals in cognitive radio networks. We assume that the noise samples are independent and identically distributed (i.i.d) random variables all with unknown (imperfect) variance. Our detection algorithm employ the following three steps. First, we formulate the test statistics as a ratio of two quadratic cyclic autocorrelation functions. Second, we derive a closed form expression for the false alarm probability. Third, we evaluate the detection probability of our algorithm for a given false alarm probability. The derived probability of false alarm expression fits to that of the simulation result. Moreover, we demonstrate that the proposed multi-cycle algorithm yields significantly superior probability of detection compared to the existing low complexity cyclostationary based and the well known energy detection algorithms. © 2012 IEEE.
%K Cognitive radio
%K Detection algorithm
%K Detection probabilities
%K Energy detection algorithm
%K False alarm probability
%K Multi-cycle
%K Noise uncertainties
%K OFDM signal
%K Orthogonal frequency division multiplexed (OFDM)
%K Probability of false alarm
%K Spectrum sensing
%K Multi-cycle cyclostationary detector
%K Superior probabilities
%K Test statistics
%K Alarm systems
%K Algorithms
%K Cognitive radio
%K Errors
%K Military communications
%K Orthogonal frequency division multiplexing
%K Probability
%K Regression analysis
%K Noise uncertainty
%K Signal detection
%K Statistical tests
%K Timing jitter
%K Spectrum sensing
%K Closed-form expression
%K Cognitive radio network
%K Cyclic autocorrelation function
%K Cyclostationary
%K Cyclostationary detectors
%K ICTEAM
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B 2012 IEEE Military Communications Conference, MILCOM 2012
%D 2012
%U Handle: http://hdl.handle.net/2078/126841
%R 10.1109/MILCOM.2012.6415704
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%T Power Scheduling for Distributed Estimation in Cluster-Based Wireless Sensor Networks
%X This work deals with the distributed estimation problem in hierarchical wireless sensor networks, where the network is divided into disjoint groups called clusters. The sensors in each cluster observe a separate random source which is correlated with the sources being observed by the other clusters. Each cluster has its designated cluster head (CH). The sensors in the clusters forward their observations to the CHs, which in turn communicate with a fusion center (FC). The estimation at the CHs and the FC is done based on the minimum mean square error estimation rule. To minimize the overall estimation distortion, we propose a power scheduling scheme that allocates power to the individual sensors and the CHs subject to constraints on the transmit powers of individual clusters and the overall network. The correlation among the underlying sources leads to coupling of the optimization variables and the power allocation solution requires centralized computation, which may be computationally expensive. To this end, we propose an alternative formulation based on an upper-bound on the distortion function, which leads to solution that exhibits favorable characteristics for distributed implementation. Simulation examples corroborate the effectiveness of the proposed power scheduling scheme.
%K Hierarchical wireless sensor networks
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Communications (ICC), 2012 IEEE International Conference on
%D 2012
%U Handle: http://hdl.handle.net/2078.1/91903
%R 10.1109/ICC.2012.6363923
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Khan, Nizabat
%A Oestges, Claude
%T Statistics of fixed relay polarimetric links using narrow-beamwidth antennas at 3.5 GHz
%X The BuNGee project (Beyond Next Generation Mobile Broadband) aims to improve the overall infrastructure capacity density provided by cellular networks to an ambitious goal of 1Gbps/km2. Its innovative architecture relies on a Hub Base Station (HBS) connected to the operator back-haul on one side and to a large number of distributed Access Base Stations (ABSs) or fixed relays on the other side (self-backhaul links), the HBSABS links being implemented by means of narrow-beamwidth dual-polarized antennas. ABSs are then connected to Mobile Subscribers (MSs), forming access links. In this contribution, the small-scale statistics of the HBS-ABS relay links are characterized by means of an advanced ray-tracing tool to reflect the peculiarities of such architecture. In particular, the dependency of small-scale statistics upon the antenna beamwidth is critically investigated. Results are simultaneously compared with the reported parameters of existing models in the literature, e.g. WINNER II and IEEE 802.16 channel models. We focus on the spatial K‐factor, spatial correlation coefficients, Cross Polarization and Co-Polar Ratios (XPR, CPR), in a dense urban deployment scenario. Furthermore, a tapped delay line model for fixed relay links with 20 MHz bandwidth is developed and analyzed.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 15th International Symposium on Wireless Personal Multimedia Communications
%D 2012
%U Handle: http://hdl.handle.net/2078.1/117976
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Universita di Bologna - DEIS
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vitucci, Enrico-Maria
%A Mani, Francesco
%A Degli-Esposti, Vittorio
%A Oestges, Claude
%T Study of a polarimetric model for diffuse scattering in urban environment
%K ICTEAM:COMM
%G Anglais
%B Proceedings 6th European Conference on Antennas and Propagation
%D 2012
%U Handle: http://hdl.handle.net/2078.1/113347
%R 10.1109/EuCAP.2012.6206681
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Tao
%A Vandendorpe, Luc
%T Successive convex approximation based methods for dynamic spectrum management
%X This paper contains two parts. The first part presents a novel framework for the successive convex approximation (SCA) method to solve a general optimization problem, as well as its properties. This framework starts with making change of variables (COV), motivated by the fact that it might be easier to construct convex approximations for the problem after making the COV. Furthermore, a general method is proposed to construct a convex upper bound approximation (CUBA) for a nonconvex function that satisfies tightness and differentiation conditions. Moreover, a way is introduced to generalize that CUBA by incorporating a convex function. These methods lead to plenty of degrees of freedom for using the SCA method to solve a problem. The second part revisits state-of-the-art dynamic spectrum management (DSM) algorithms, namely the successive convex approximations for low-complexity (SCALE) algorithm, the convex approximation for distributed spectrum balancing (CA-DSB) algorithm and the difference-of-convex-functions algorithm based DSM (DCA-DSM) method, to show how they can be derived from the SCA and CUBA construction methods. Numerical experiments are shown to compare them. © 2012 IEEE.
%K Digital subscriber lines
%K Dynamic spectrum management
%K Power control
%K Successive convex approximation
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B 2012 IEEE International Conference on Communications, ICC 2012
%D 2012
%U Handle: http://hdl.handle.net/2078.1/122054
%R 10.1109/ICC.2012.6363727
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Kalakech, Ali
%A Berbineau, Marion
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Time Domain Channel Estimation in OFDM Systems Using limited number of Pilot Tones
%X This paper deals with the time domain estimation of OFDM channels in the case of a limited number of pilot tones. In such situations, time domain estimation suffers from an ill conditioned sample matrix which render the Least Square (LS) algorithm non efficient. To improve the estimation procedure, two algorithms are proposed. The first algorithm improves the conditioning of the LS matrix by adding a corrective term or penalization factor to the LS pseudo inverse matrix. The second algorithm tries to partially remove the effect of the penalization factor iteratively. Computational results are provided for the case of crosstalk channel estimation in DSL system these results show the effectiveness of the different methods.
%G Anglais
%B Proceedings International Symposium on Signal, Image, Video and Communications 2012
%D 2012
%U Handle: http://hdl.handle.net/2078.1/130708
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute of Information and Communication Technologies, Electronics and Applied Mathematics
%A Bogale, Tadilo Endeshaw
%A Vandendorpe, Luc
%T Weighted sum rate optimization for downlink multiuser MIMO systems with per antenna power constraint: Downlink-uplink duality approach
%X This paper considers weighted sum rate maximization constrained with a per base station (BS) antenna power problem for multiuser multiple-input multiple-output (MIMO) systems. For this problem, we propose new downlink-uplink duality based solution. We solve the problem as follows. First, by introducing additional optimization variables, we reformulate our problem into an equivalent problem that incorporates a weighted sum mean-square-error (MSE) term. Second, we establish novel weighted sum MSE duality. The duality is established by modifying the input covariance matrix of the dual uplink problem, and formulating the noise covariance matrix of the uplink channel as a fixed point function. Third, we optimize the introduced variables and powers in the downlink channel by a Geometric Program (GP) method. Fourth, using the duality result and the solution of GP, we apply alternating optimization technique to solve the original downlink problem. In our simulation results, we have observed that the proposed duality based solution utilizes less power than that of existing algorithms. © 2012 IEEE.
%K MIMO
%K MSE duality
%K Multiuser multiple-input multiple-output systems
%K Noise covariance matrix
%K Optimization variables
%K Per-antenna power constraints
%K Power problem
%K Uplink channel
%K Weighted Sum
%K Weighted sum-rate
%K Antennas
%K Throughput
%K Covariance matrix
%K MIMO systems
%K Optimization
%K Signal processing
%K Throughput
%K Transceivers
%K Problem solving
%K Transceivers
%K Alternating optimizations
%K Base station antennas
%K Downlink channels
%K Downlink multiuser MIMO systems
%K Fixed point function
%K Geometric program
%K ICTEAM:COMM
%K ICTEAM:
%K ICTEAM:SIGN
%G Anglais
%B Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on
%D 2012
%U Handle: http://hdl.handle.net/2078/116824
%R 10.1109/ICASSP.2012.6288607
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ ULB - OPERA
%A Van Roy, Stéphane
%A Oestges, Claude
%A Dricot, Jean-Marie
%A Horlin, François
%A De Doncker, Philippe
%T A Tapped Delay Line Model of Ground Reflection for UWB MS-MIMO Body Area Networks
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77841
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ University of Pisa - Telecommunications Dpt
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Giannetti, F.
%A Stupia, Ivan
%A Lottici, V.
%A Andreotti, R.
%A D'Andrea, A.N.
%A Vandendorpe, Luc
%T A performance prediction model for BIC-OFDM transmissions with AMC over nonlinear fading channels
%X This paper presents an accurate tool yielding a reliable prediction of the link quality for the down-link of a BIC-OFDM system featuring bandlimited pulse shaping to control spectral sidelobe emission, plus AMC, and operating over a nonlinear channel. The tool enables an effective design of the communication system, with special respect to the setting of the operating point of the transmitter's power amplifier. First, an analytical characterization of the nonlinear distortion effects caused by the amplifier on bandlimited BIC-OFDM signals is carried out by resorting to the extended version of the Bussgang theorem. Then, the equivalent additive noise model provided by the Bussgang-based analysis is taken into account in the derivation of a novel link quality prediction method, named BkappaESM. Finally, the novel BkappaESM tool is employed in the link design phase for choosing the best amplifier setting, aimed at maximizing the layer-3 offered traffic over a realistic wireless channel, featuring both multipath propagation and nonlinear distortions.
%K ICTEAM:COMM
%G Anglais
%B 8th International Workshop on Multi-Carrier Systems & Solutions (MC-SS2011)
%I IEEE
%C Piscataway
%D 2011
%U Handle: http://hdl.handle.net/2078.1/83532
%R 10.1109/MC-SS.2011.5910726
%R 10.1109/MC-SS.2011.5910726
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%A Zaidi, Abdellatif
%A El Soussi, Mohieddine
%A Vandendorpe, Luc
%T Codage Réseau pour Canal à Accès Multiple avec Relai
%X In this work, we study a multiaccess relay channel (MARC). The system consists of two transmitters communicating with a destination with the help of a half-duplex relay. We extend and adapt the recently proposed lattice-based compute-and-forward coding scheme to the model we study. This coding scheme can be seen as a form of some network-coding that is implemented at the relay through modulo reduction. In this scheme, the destination decodes two linear equations with integer coefficients that relate the transmitted symbols at different computational rates. First, we discuss the design criteria, and derive the allowed computation rate. Then, we optimally allocate the different parameters by solving a series of geometric programs through the approach of successive convex approximation. The analysis shows that our coding scheme can offer substantial gain over the standard amplify-and-forward and decode-and-forward for this model. We illustrate our results through some numerical examples.
%G Français
%B Gretsi
%D 2011
%U Handle: http://hdl.handle.net/2078/122947
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Aalto University - SMARAD
%+ Lund University - Lund University
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Haneda, Katsuyuki
%A Poutanen, Juho
%A Tufvesson, Fredrik
%A Liu, Lingfeng
%A Kolmonen, Veli-Matti
%A Vainikainen, Perti
%A Oestges, Claude
%T Development of multi-link geometry-based stochastic channel models
%K ICTEAM:COMM
%G Anglais
%B Proceedings Loughborough Antennas and Propagation Conference
%D 2011
%U Handle: http://hdl.handle.net/2078.1/113346
%R 10.1109/LAPC.2011.6114003
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ FTW - FTW
%A Oestges, Claude
%A Czink, Nicolai
%T Empirical Investigation of Multi-Link Separation for Indoor MIMO Channels
%X Based on multi-node multi-antenna channel measurements in a multi-wall office environment, we estimate the degree of separation between multiple MIMO links by means of two metrics: the correlation matrix distance and the shadowing correlation. Both nomadic and mobile node scenarios are considered and compared. Empirical models are eventually derived. Our analysis reveals that the average separation between two MIMO links sharing a joint transmitter is usually lower in mobile scenarios than in nomadic scenarios, and is strongly related to the spatial correlation of the individual MIMO links. However, there appears to be no relationship between the correlation matrix distance and the shadowing correlation.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 22nd IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2011
%U Handle: http://hdl.handle.net/2078.1/87017
%R 10.1109/PIMRC.2011.6140108
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ ULB - OPERA
%A Quitin, François
%A Oestges, Claude
%A Bellens, François
%A Van Roy, Stéphane
%A Horlin, François
%A De Doncker, Philippe
%T Extracting specular-diffuse clusters from MIMO channel measurements
%K ICTEAM:COMM
%G Anglais
%B Proceedings 22nd IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2011
%U Handle: http://hdl.handle.net/2078.1/87021
%R 10.1109/PIMRC.2011.6140107
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ FTW - FTW
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ TU Wien
%A Sanchez, Fernando
%A Czink, Nicolai
%A Oestges, Claude
%A Stephanides, Andreas
%T Fast Fading Characterization for Indoor to Indoor and Outdoor to Indoor Channels
%X This work models the fast fading characteristics in indoor to indoor and outdoor to indoor channels at 3.8 GHz. Starting from real world measurements, the fast fading characteristics are extracted and properly modeled, taking into account the nodes movement conditions. For static environments, the fast fading is modeled with the well known Ricean distribution. As expected the K-factor depends on the path loss. On the other hand, in mobile environments, the probability density function of the signal envelope is accurately described by the recently developed second-order scattering fading (SOSF) distribution. The SOSF distribution combines the Rayleigh, Ricean and double Rayleigh fading and any linear combinations of these. Our results show that the higher the mobility, the more severe is the fading.
%K Fading channels
%K fast fading
%K channel modeling
%K SOSF
%K ICTEAM:COMM
%G Anglais
%B Proceedings 74th IEEE Vehicular Technology Conference Fall
%D 2011
%U Handle: http://hdl.handle.net/2078.1/87009
%R 10.1109/VETECF.2011.6092969
%* peer-reviewed
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Nour, Reda
%A Pedrosa, Pedro
%A Louveaux, Jérôme
%A Horlin, François
%+ ULB - OPERA
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T Frequency Selective Channel Equalization for Filter Bank Multi-Carriers Modulation
%D 2011
%X The filter bank multicarrier modulation (FBMC) is a transmission technique better suited for new concepts such as dynamic access spectrum management (DASM) and cognitive radio. It is used to improve the efficiency of mobile radio and wireless communication networks, because it allows reaching a high data rate and improving spectral efficiency. The FBMC principle exploits the concept of better waveform localization in both time and frequency domains, unlike orthogonal frequency division multiplexing...
%G Anglais
%B Symposium on Information Theory in the Benelux, 2011
%C Brussels, Belgium
%8 05/10/2011
%U Handle: http://hdl.handle.net/2078.1/137453
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Khan, Nizabat
%A Oestges, Claude
%T Impact of Transmit Antenna Beamwidth for Fixed Relay Links Using Ray-Tracing and Winner II Channel Models
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77829
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ ULB - OPERA
%A Liu, Lingfeng
%A Bhatnagar, Vaibhav
%A Garcia Robles, Cristina
%A De Doncker, Philippe
%A Vandendorpe, Luc
%A Oestges, Claude
%T Investigation of Channel Spatial Diversity for Dual-link Cooperative Communications in WBAN
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77905
%* peer-reviewed
%0 Book Section
%9 Conférence invitée / Keynote
%A Awan, Zohaib Hassan
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T MAC with Partially Cooperating Encoders and Security Constraints
%X We study a special case of Willems's two-user multiaccess channel with partially cooperating encoders from security perspective. This model differs from Willems's setup in that only one encoder, Encoder 1, is allowed to conference, Encoder 2 does not transmit any message, and there is an additional passive eavesdropper from whom the communication should be kept secret. For the discrete memoryless case, we establish inner and outer bounds on the rate-equivocation region. Furthermore, we show that these bounds coincide in the case of perfect secrecy, and so we characterize fully the secrecy capacity. For the Gaussian model, we establish lower and upper bounds on the perfect secrecy rate. We also show that these bounds agree in some extreme cases of cooperation between encoders. We illustrate our results through some numerical examples.
%G Anglais
%B VALUETOOLS '11, 5th International ICST Conference on Performance Evaluation Methodologies and Tools
%D 2011
%U Handle: http://hdl.handle.net/2078/122915
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Bogale, Tadilo Endeshaw
%A Vandendorpe, Luc
%T MSE uplink-downlink duality of MIMO systems with arbitrary noise covariance matrices
%X This paper establishes three kinds of mean-square-error (MSE) uplink-downlink duality for multiple-input multiple-output (MIMO) systems. Our duality is established for the practically relevant scenario where the noise vector of each mobile station (MS) is a zero-mean circularly symmetric complex Gaussian (ZMCSCG) random variable with arbitrary covariance matrix. As an application example of our duality, we examine the linear transceiver design for the weighted sum MSE minimization constrained with a total base station (BS) power problem for the downlink multiuser MIMO systems. To solve this problem, first we establish the MSE uplink-downlink duality. Then, we formulate the power allocation part of the equivalent problem in the uplink channel as a Geometric Programming (GP). Finally, using the duality result and the solution of GP, we utilize alternating optimization technique to solve the original downlink problem. The proposed duality maintains the easier-to-handle mathematical structure of MSE-based problems in the uplink channel and generalizes the existing MSE uplink-downlink duality. Furthermore, by utilizing our duality, we exploit the hidden convexity of the sum MSE minimization constrained with a total BS power problem in the downlink channel.
%K Theoretical or Mathematical/ covariance matrices
%K Gaussian channels
%K Multiple-input multiple-output system
%K Noise vector;mobile station
%K Zero-mean circularly symmetric complex Gaussian randomvariable
%K ZMCSCG
%K Linear transceiver design
%K Base station
%K Downlinkmultiuser MIMO system
%K Power allocation
%K Geometric programming;optimization technique
%K Uplink channel/ B6250 Radio links and equipmentB0260 Optimisation techniquesB0290H Linear algebra (numerical analysis)B0290F Interpolation and function approximation (numerical analysis)
%K Geometric programming
%K Meansquare error methods
%K MIMO communication
%K MIMO systems
%K Multiuserchannels
%K Radio transceivers/ mean square error uplink-downlink duality
%K Arbitrary noise covariancematrix
%K MSE
%K ICTEAM:COMM
%G Anglais
%B 2011 45th Annual Conference on Information Sciences and Systems (CISS2011)
%I IEEE
%C Piscataway, NJ, USA
%D 2011
%U Handle: http://hdl.handle.net/2078.1/84115
%R 10.1109/CISS.2011.576613310.1109/CISS.2011.5766133
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gan, Mingming
%A Czink, Nicolai
%A Castiglione, Paolo
%A Oestges, Claude
%T Modeling time-variant fast fading statistics of mobile peer-to-peer radio channels
%X The radio channels between nodes of an indoor peer-to-peer network show specific fast fading characteristics. Depending on the mobility and on the scattering properties of the environment, different kinds of fading distributions can occur: Ricean fading between static nodes, but also Rayleigh or even double-Rayleigh fading between mobile nodes. We investigate fast fading in indoor peer-to-peer networks based on radio channel measurements. It turns out that the fading statistics change over time. While the predominant fading mechanism is a combination of Rayleigh and double-Rayleigh fading, Ricean fading also occasionally occurs. On top of that, indoors, the statistics of the fast fading change over time even for small-motions of the nodes, since the propagation environment is inhomogeneous. We comprehensively model these effects using a hidden Markov model, parameterized from our measurements. The model is validated, revealing a convincing fit between the model and the measurements.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 73rd IEEE Vehicular Technology Conference Spring
%D 2011
%U Handle: http://hdl.handle.net/2078.1/118286
%R 10.1109/VETECS.2011.5956129
%* peer-reviewed
%0 Book Section
%9 Conférence invitée / Keynote
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oestges, Claude
%T Multi-Link Propagation Modeling for Beyond Next Generation Wireless (invited paper)
%K ICTEAM:COMM
%G Anglais
%B Proceedings Loughborough Antennas and Propagation Conference
%D 2011
%U Handle: http://hdl.handle.net/2078.1/105530
%R 10.1109/LAPC.2011.6114008
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Gusi Amigo, Adria
%A Mallat, Achraf
%A Vandendorpe, Luc
%T Multiuser and multipath interference mitigation in UWB TOA estimation
%X In this paper we consider the impact of MUI (multiuser interference) on coherent TOA (time of arrival) estimation. We consider TH-PPM (time-hopping pulse position modulation). We propose estimators based on the ML (maximum likelihood) criterion together with interference cancellation. We propose algorithms for SP (single-path) and MP (multipath) communication channels. We report simulation results and we conclude that the proposed estimators obtain smaller variance than the per-user ML estimator. Moreover, with well-chosen signature parameters, it is possible to reach the CRB (Cramèr-Rao bound) when multiple sources are transmitting in SP channels and values close to the CRB in MP channels. We also show that the interference cancellation technique makes the estimation robust against near-far situations.
%G Anglais
%B Ultra-Wideband (ICUWB), 2011 IEEE International Conference on
%I IEEE
%D 2011
%U Handle: http://hdl.handle.net/2078.1/130909
%R 10.1109/ICUWB.2011.6058887
%* peer-reviewed
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Di Dio, Mario
%A Luise, Marco
%A Zanier, Francesca
%A Mallat, Achraf
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%+ Università di Pisà - Dipartimento di Ingegneria dell'Informazione
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T On delay estimation with multicarrier signals and its relation with cognitive positioning
%D 2011
%G Anglais
%B Newcom++ Cost 2100 Joint Workshop on Wireless Communications
%C Paris, France
%8 du 01/03/2011 au 02/03/2011
%U Handle: http://hdl.handle.net/2078.1/137455
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Aalto University
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Lund University
%A Poutanen, Juho
%A Haneda, Katsuyuki
%A Liu, Lingfeng
%A Oestges, Claude
%A Tufvesson, Fredrik
%A Vainikainen, Pertti
%T Parameterization of the COST 2100 MIMO Channel Model in Indoor Scenarios
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77901
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%T Power Constrained Linear Estimation of Correlated Sources in Hierarchical Wireless Sensor Networks
%K Hierarchical Wireless Sensor Networks
%K Correlated Sources
%K Estimation
%K Adaptive Power Allocation
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B Signal Processing Advances in Wireless Communications (SPAWC), 2011 IEEE 12th International Workshop on
%I IEEE
%D 2011
%U Handle: http://hdl.handle.net/2078.1/78745
%R 10.1109/SPAWC.2011.5990382
%* peer-reviewed
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Van Caekenberghe, Stijn
%A Pollin, Sofie
%A Bourdoux, André
%A Van der Perre, Liesbet
%A Louveaux, Jérôme
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T Preamble-based channel estimation for filterbank multicarrier wireless systems
%D 2011
%X Three preamble-based channel estimation techniques are discussed that can be used in lterbank multicarrier systems. The rst one was described by Lele in [1] for FBMC with IOTA lters. The second one is based on the auxiliary pilot method described by Stitz in [2]. The last one is suggested in this paper. The three techniques are compared with BER curves as well as by looking at the origin of their errors.
%G Anglais
%B 32nd WIC Symposium on Information Theory in the Benelux
%C Brussels, Belgium
%8 05/10/2011
%U Handle: http://hdl.handle.net/2078.1/137454
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%T Quantization and Power Allocation in Wireless Sensor Networks with Correlated Data
%K Wireless Sensor Networks
%K Spatial Correlation
%K Estimation
%K Quantization
%K Power Allocation
%K ICTEAM:COMM
%K ICTEAM:COMM
%G Anglais
%B Acoustics, Speech and Signal Processing (ICASSP), 2011 IEEE International Conference on
%D 2011
%U Handle: http://hdl.handle.net/2078.1/78744
%R 10.1109/ICASSP.2011.5946293
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mani, Francesco
%A Oestges, Claude
%T Ray-tracing evaluation of diffuse scattering in an outdoor scenario
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77854
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%A El Soussi, Mohieddine
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Resource allocation for multiple access relay channel with a compute-and-forward relay
%X In this work, we study a multiaccess relay channel (MARC). The system consists of two transmitters communicating with a destination with the help of a half-duplex relay. We extend and adapt the recently proposed lattice-based compute-and-forward coding scheme to the model we study. This coding scheme can be seen as a form of some network-coding that is implemented at the relay through modulo-reduction. In this scheme, the destination decodes two linear equations with integer coefficients that relate the transmitted symbols at different computational rates. First, we discuss the design criteria, and derive the allowed computation rate. Then, we optimally allocate the different parameters by solving a series of geometric programs using successive convex approximation methods. The analysis shows that our coding scheme can offer substantial gain over the standard amplify-and-forward and decode-and-forward for this model. We illustrate our results through some numerical examples.
%G Anglais
%B International Symposium on Wireless Communication Systems (ISWCS)
%D 2011
%U Handle: http://hdl.handle.net/2078/122943
%R 10.1109/ISWCS.2011.6125274
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ University of Vigo
%+ ESA - ESTEC
%+ Fraunhofer Institute for Integrated Circuits
%A Montenegro Villacieros, Belén
%A Oestges, Claude
%A Perez-Fontan, Fernando
%A Prieto-Cerdeira, Roberto
%A Heyn, Thomas
%A Eberlein, Ernst
%A Vanhoenacker-Janvier, Danielle
%T Stationarity Study of Land Mobile Satellite Channel in View of Developing a Time Series Generator
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77908
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Panahandeh, Ali
%A Oestges, Claude
%A Dricot, Jean-Michel
%A Horlin, François
%A De Doncker, Philippe
%T Study of the Temporal Dynamics of the Polarization of Received Electromagnetic Waves Based on an Indoor-to-Indoor Measurement Campaign
%X Compared to classical spatial MIMO wireless systems, cross-polarized MIMO systems are an interesting way to reduce equipment size while still maintaining low inter-antenna correlation. In this paper, the time-variation of the polarization of the received waves is investigated. In this scenario, a theoretical formulation is proposed in order to obtain the parameters of the elliptical polarization, based on the signals received on three perpendicularly polarized antennas. A measurement campaign has been performed in an indoor-to-indoor scenario and at a frequency of 3.6 GHz. Different measurement positions are considered in a Line-Of-Sight (LOS) and a Non-Line-of- Sight (NLOS) scenario. Based on these measurements and the proposed theoretical formulation, the timevariation of the parameters describing the polarization ellipse is analyzed and a time-variant statistical model is proposed.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 23rd Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2011
%U Handle: http://hdl.handle.net/2078.1/117960
%R 10.1109/PIMRC.2012.6362689
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ FTW - FTW
%+ Stanford University - ISL
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Czink, Nicolai
%A Bandemer, Bernd
%A Oestges, Claude
%A Zemen, Thomas
%A Paulraj, Arogyaswami
%T Subspace Modeling of Multi-User MIMO Channels
%X In multiple-input multiple-output (MIMO) systems, the propagation channels can be characterized by their spatial structure, described by the (complex-valued) channel correlation. Accordingly, also interference in MIMO systems is likely to occur in a spatially structured, correlated way. We discuss that structured spatial interference affects mutual information under interference, depending on the eigenspace alignment between the channel of the desired signal and the channel carrying the interference. Intuitively, worst-case interference occurs, when the channels from the intended signal and the interference show a similar spatial structure. In contrast, least hurtful interference is encountered when these channels are maximally non-aligned. In this paper, we develop an analytical channel model generating multi-user MIMO channels with a given degree of severity of interference, described by the alignment of the channels’ eigenspaces. Using radio channel measurements, we parameterize our model to reflect realistic scenarios.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 74th IEEE Vehicular Technology Conference Fall
%D 2011
%U Handle: http://hdl.handle.net/2078.1/87001
%R 10.1109/VETECF.2011.6092968
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Bogale, Tadilo Endeshaw
%A Vandendorpe, Luc
%T Sum Rate Optimization for Coordinated Multi-antenna Base Station Systems
%X This paper considers the joint precoder design problem for multiple-input single-output (MISO) systems with coordinated base stations (BSs). We consider maximization of the total sum rate with per BS antenna power constraint problem. For this problem, we propose a novel linear iterative algorithm. The problem is solved as follows. First, by introducing additional optimization variables and applying matrix fractional minimization, we reformulate the original problem as a new problem. Second, for the given precoder vectors of all users, we optimize the introduced variables of the latter problem using Geometric Programming (GP) method. Third, keeping the introduced variables constant, the precoder vectors of all users are optimized by using phase rotation technique. The second and third steps are repeated until convergence. We have shown that the proposed algorithm is guaranteed to converge. Moreover, for the total sum power constraint case, simulation results show that the proposed iterative algorithm achieves almost the same average performance as that of the algorithm which utilizes mean-square-error (MSE) uplink-downlink duality approach. We also show that our iterative algorithm can be used to solve sum rate maximization and weighted sum MSE minimization problems for an arbitrary power constraint.
%K Practical, Theoretical or Mathematical/ iterative methods
%K Mean square error methods
%K Optimisation
%K Radionetworks/ sum rate optimization
%K Coordinated multiantenna base station systems;joint precoder design problem
%K Multiple-input single-output systems;coordinated base stations
%K Linear iterative algorithm
%K Optimizationvariables
%K Matrix fractional minimization
%K Geometric programming;mean-square-error uplink-downlink duality approach/ B6250 Radio links and equipmentB0260 Optimisation techniquesB0290F Interpolation and function approximation (numerical analysis)
%K ICTEAM:COMM
%K ICTEAM:SIGN
%G Anglais
%B ICC 2011 - 2011 IEEE International Conference on Communications
%I IEEE
%C Piscataway, NJ, USA
%D 2011
%U Handle: http://hdl.handle.net/2078.1/85311
%R 10.1109/icc.2011.596344610.1109/icc.2011.5963446
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Aalto University
%A Renaudin, Olivier
%A Kolmonen, Veli-Matti
%A Vainikainen, Pertti
%A Oestges, Claude
%T Wideband Measurement-Based Modeling of Inter-Vehicle Channels in the 5 GHz Band
%K ICTEAM:COMM
%G Anglais
%B Proceedings 5th European Conference on Antennas and Propagation
%D 2011
%U Handle: http://hdl.handle.net/2078.1/77835
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Liu, Lingfeng
%A Keshmiri, Farshad
%A De Doncker, Philippe
%A Craeye, Christophe
%A Oestges, Claude
%T 3-D body scattering interference to vertically polarized on-body propagation
%X In this paper, we developed an analytical model of vertically polarized on-body propagation to describe the body scattering interference to the on-body channels. The 3-D dimension scattering from the trunk and arms by a point source are considered. Measurements results in an anechoic chamber at 2.45 GHz are also presented to validate the model.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Symposium Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67338
%R 10.1109/APS.2010.5561074
%* peer-reviewed
%Z Lingfeng Liu; Oestges, C.; EMIC, Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium Keshmiri, F.; Craeye, C.; TELE, Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Stupia, Ivan
%A Giannetti, F.
%A Lottici, V.
%A Vandendorpe, Luc
%T A Greedy Algorithm for Goodput-Based Adaptive Modulation and Coding in BIC-OFDM Systems
%X This paper develops cross-layer adaptive modulation and coding as an efficient method for bit interleaved coded OFDM packet transmission. As objective function, we adopt the goodput, or the number of data bits delivered without error per unit of time. After the formalization of the optimization problem through an accurate modeling on the link performance, an iterative solution is derived based on the framework of greedy algorithms. Simulation results show that the proposed method improves upon the performance of static transmission and uniform bit allocation by 2-4 dB.
%B 2010 European Wireless Conference (EW)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67409
%R 10.1109/EW.2010.5483466
%* peer-reviewed
%Z Stupia, I.; Giannetti, F.; Lottici, V.; Dept. of Inf. Eng., Univ. of Pisa, Pisa, Italy Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Brah, Félix
%A Vandendorpe, Luc
%A Ramon, Valery
%T A Tractable Method for Constrained Resource Sharing in OFDMA Wireless Mesh Networks
%X This paper presents a novel fair scheme for resource sharing between nodes in OFDMA mesh networks. The problem is to maximize the overall system rate, under each user's maximal power and minimum rate constraints. To solve the underlying problem, we propose an approach that combines the merits of the well known Lagrange dual framework and the Lambert-W function. By using the Lambert-W function, resource allocation can not only be expressed in closed form but it can also quickly be determined without resorting to complex algorithms since a number of popular mathematical softwares, including Matlab, contain the Lambert-W function as an optimization component. Simulation results are provided to compare the performance of the proposed scheme with other allocation schemes.
%B ICC 2010 - 2010 IEEE International Conference on Communications
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67381
%R 10.1109/ICC.2010.5502032
%R 10.1109/ICC.2010.5502032
%* peer-reviewed
%Z Brah, F.; Vandendorpe, L.; Sch. of Eng., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Ramon, V.; Interuniv. Micro-Elektronica Centrum, Leuven, Belgium
%0 Conference Paper
%A Stupia, Ivan
%A Giannetti, F.
%A Lottici, V.
%A Andreotti, R.
%A Vandendorpe, Luc
%A D'Andrea, A.N.
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T A greedy algorithm for goodput-oriented AMC in turbo-coded OFDM
%D 2010
%X This paper presents a novel technique for cross-layer adaptive modulation and coding, suited for bit interleaved turbo-coded OFDM packet transmission, and aimed at maximizing the goodput (i.e., the number of data bits delivered without error per unit of time). The optimization problem is formalized through an accurate modeling on the link performance, and a greedy iterative solution is derived. Simulation results demonstrate that performance improvement provided by the proposed method amount to 4 dB with respect to static transmission and about 1.2 dB with respect to adaptive transmission with uniform bit allocation. Copyright © The authors.
%K Adaptive modulation and coding
%K Greedy algorithm
%K Greedy algorithms
%K Iterative solutions
%K Link performance
%K Novel techniques
%K Number of datum
%K Optimization problems
%K Packet transmissions
%K Per unit
%K Performance improvements
%K Greedy algorithm
%K Simulation result
%K Turbo-coded
%K Algorithms
%K Delta modulation
%K Optimization
%K Orthogonal functions
%K Wireless networks
%K Adaptive modulation
%K Turbo-codes
%K Accurate modeling
%K Adaptive modulation and coding
%K Adaptive transmission
%K Bit allocation
%K Cross-layer adaptive
%K Good put
%G Anglais
%B 2010 Future Network and Mobile Summit
%C Florence
%8 du 16 June 2010 au 18 June 2010
%U Handle: http://hdl.handle.net/2078.1/138715
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ INRIA - Centre Rennes Bretagne Atlantique, Campus universitaire de Beaulieu, Rennes, France
%A Oguz, Onur
%A Herzet, Cedric
%A Vandendorpe, Luc
%T A novel adaptive iterative detection technique for joint estimation and detection
%X Reliability of the communication systems depends hugely on the receiver performance where the synchronization and detection tasks need to be performed. Classically these two tasks are attended separately resulting in simple yet non-optimal receivers. During the last decade, a family of iterative receivers has been introduced to approximate the optimal solution to joint estimation and detection problem by means of the turbo principle. With the help of graph theory and the belief propagation framework these receiver structures are unified and soft information driven schemes emerged, leading to more reliable detection. The essence of these schemes lays in factorization of a global function whose marginal corresponds to the objective function and obtained via simple message passing algorithms. On the other hand, as far as our knowledge, all of the proposed structures pursue a specific factorization while devising their respective schemes. In this work utilizing a different factorization, we introduce a novel iterative receiver for joint equalization/detection problem. With the aid of Variational Bayesian approximation we show that the complexity can be reduced without sacrificing the error performance drastically.
%K Bayes methods
%K Equalisers
%K Synchronization
%K Turbo principle
%K Graph theory
%K Belief propagation
%K Message passing algorithms
%K Factorization
%K Iterative receiver
%K Equalization
%K Variational Bayesian approximation
%K Graph theory
%K Iterative methods
%K Message passing
%K Radio receivers
%K Synchronisation
%K Telecommunication network reliability
%K Adaptive iterative detection technique
%K Communication system reliability
%K 2556
%G Anglais
%B 2010 IEEE 21st International Symposium on Personal, Indoor and MobileRadio Communications (PIMRC 2010)
%D 2010
%U Handle: http://hdl.handle.net/2078.1/74618
%R 10.1109/PIMRC.2010.5671619
%R 10.1109/PIMRC.2010.5671619
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ University of Bologna
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vitucci, Enrico M.
%A Mani, Francesco
%A Degli-Esposti, Vittorio
%A Oestges, Claude
%T A study on polarimetric properties of scattering from building walls
%K ICTEAM:COMM
%G Anglais
%B Proceedings 72nd IEEE Vehicular Technology Conference Fall
%D 2010
%U Handle: http://hdl.handle.net/2078.1/105538
%R 10.1109/VETECF.2010.5594352
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Aalto University
%A Renaudin, Olivier
%A Kolmonen, Veli-Matti
%A Vainikainen, Pertti
%A Oestges, Claude
%T About the multipath stationarity of car-to-car channels in the 5 GHz band
%K ICTEAM:COMM
%G Anglais
%B Proceedings URSI International Symposium on Electromagnetic Theory
%D 2010
%U Handle: http://hdl.handle.net/2078.1/105537
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A D'Orazio, L.
%A Sacchi, C.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Adaptive minimum conditional bit-error-rate linear multiuser detection for STBC-MC-CDMA systems transmitting over mobile radio channels
%X This paper proposes an adaptive Minimum Conditional Bit-ErrorRate (MCBER) Multi-User Detector (MUD) for a Space-Time Block Coded Multi-Carrier Code Division Multiple Access (STBC MC-CDMA) system that is based on Least-Mean-Square (LMS) optimization algorithm. Theoretical basics and simulation results have been presented and discussed for the proposed detector. Results shown in terms of BER evidenced that the MCBER detector outperforms the adaptive LMS-based implementation of MMSE MUD and also the ideal MMSE MUD exploiting the perfect knowledge of channel state-information. The moderate computational effort and the reduced sensitivity to parameterization seem to represent other relevant strengths of the proposed approach.
%B Multiple Access Communications. Third International Workshop, MACOM 2010
%E Vinel, A.; Bellalta, B.; Sacchi, C.; Lyakhov, A.; Telek, M.;
%I Springer
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67331
%R 10.1007/978-3-642-15428-7_4
%R 10.1007/978-3-642-15428-7_4
%* peer-reviewed
%Z D'Orazio, L.; SIEMENS S.p.A. Ind. Sector, Milan, Italy Sacchi, C.; Dept. of Inf. Eng. & Comput. Sci. (DISI), Univ. of Trento, Povo, Italy Louveaux, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Al Kadi Jazairli, Mohamad
%A Mallat, Achraf
%A Vandendorpe, Luc
%A Flandre, Denis
%T An Ultra-Low-Power frequency-tunable UWB pulse generator using 65nm CMOS technology
%K CMOS
%K UWB
%K Ultra-Wideband
%K ICTEAM:CIRC
%G Anglais
%B Proceedings of ICUWB, IEEE International Conference on Ultra-Wideband
%D 2010
%U Handle: http://hdl.handle.net/2078.1/106304
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Kalakech, Ali
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Application of gradient algorithm for optimizing power allocation in DSL systems
%X The optimization of power allocation in DSL systems is a well studied non-convex problem. In recent years many algorithms have been proposed to solve this problem, but due to its non-convexity, researchers had to rely on heuristic, or exhaustive research methods. In our approach we make use of the similarities of the channel gain between 2 adjacent tones to overcome the non-convexity limitation of gradient methods. This allows the proposition of an efficient and a fast routine that manages to speed up the convergence of existent state of the art algorithms.
%B 2010 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2010
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67332
%R 10.1109/ICASSP.2010.5496079
%R 10.1109/ICASSP.2010.5496079
%* peer-reviewed
%Z Kalakech, A.; Louveaux, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., UCL, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%T Battery-Aware Power Allocation for Lifetime Maximization of Wireless Sensor Networks
%X We consider a wireless sensor network deployed to observe a physical phenomenon. The sensors amplify and forward their observations to a remote fusion center via single hop. The objective is to maximize the operational lifetime of the network such that the estimate of the underlying source at FC satisfies a certain fidelity criterion given by the maximum tolerable estimation distortion. Each sensor is powered by a battery which limits its lifetime and consequently of the network also. Recent studies show that the battery discharge behavior is dependent on the load current: higher current leads to higher losses inside the battery due to the non-linearities of the electrochemical reaction in the battery. This work presents a power allocation design where goal is to maximize the network lifetime incorporating the non-linear discharging behavior of the batteries. The design is based on the knowledge of the instantaneous channel gains as well as when we only know the channel statistics. The numerical examples illustrate that the impact of battery-aware power scheduling on the network life is substantial.
%K Wireless Sensor Networks
%K Nonlinear Battery Discharging
%K BLUE Estimation
%K Battery Aware Power Allocation
%G Anglais
%B Communications (ICC), 2010 IEEE International Conference on
%D 2010
%U Handle: http://hdl.handle.net/2078.1/78747
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Fontanella, D.
%A Nicoli, M.
%A Vandendorpe, Luc
%T Bayesian Localization in Sensor Networks: Distributed Algorithm and Fundamental Limits
%X Self-localization in ad-hoc sensor networks is becoming a crucial issue for several location-aware applications. This technology implies the combination of absolute anchor locations with relative inter-node information exchanged on a peer-to-peer basis. In this paper we investigate a distributed algorithm and fundamental performance bounds for Bayesian cooperative localization in stochastic networks. Nodes are assumed to be randomly deployed within a finite space according to a prior distribution. Bayesian inference is performed through an iterative local message passing procedure based on belief propagation and particle-filtering message representation. The algorithm performance is analyzed for a simplified scenario in which unknown node positions are randomly scattered along a line segment and anchors are fixed. Global Cramer-Rao bounds are derived and compared to the performance of the distributed algorithm.
%B ICC 2010 - 2010 IEEE International Conference on Communications
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67383
%R 10.1109/ICC.2010.5502618
%R 10.1109/ICC.2010.5502618
%* peer-reviewed
%Z Fontanella, D.; Nicoli, M.; Dip. di Elettron. e Inf., Politec. di Milano, Milan, Italy Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain la Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Zaidi, Abdellatif
%A Shamai, S.
%A Piantanida, P.
%A Vandendorpe, Luc
%T Bounds on the capacity of the relay channel with noncausal state information at source
%X We consider a three-terminal state-dependent relay channel with the channel state available non-causally at only the source. Such a model may be of interest for node cooperation in the framework of cognition, i.e., collaborative signal transmission involving cognitive and non-cognitive radios. We study the capacity of this communication model. One principal problem in this setup is caused by the relay's not knowing the channel state. In the discrete memoryless (DM) case, we establish lower bounds on channel capacity. For the Gaussian case, we derive lower and upper bounds on the channel capacity. The upper bound is strictly better than the cut-set upper bound. We show that one of the developed lower bounds comes close to the upper bound, asymptotically, for certain ranges of rates.
%B 2010 IEEE International Symposium on Information Theory. ISIT 2010
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67362
%R 10.1109/ISIT.2010.5513564
%R 10.1109/ISIT.2010.5513564
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Ecole Polytech. de Louvain, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Shamai, S.; Dept. of EE, Technion - Israel Inst. of Technol., Haifa, Israel Piantanida, P.; Dept. of Telecommun., SUPELEC, Gif-sur-Yvette, France
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Aalto University
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Haneda, Katsuyuki
%A Poutanen, Juho
%A Liu, Lingfeng
%A Oestges, Claude
%T Comparison of delay and angular spreads between channel measurements and the COST 2100 channel model
%K ICTEAM:COMM
%G Anglais
%B Proceedings Loughborough Antennas & Propagation Conference
%D 2010
%U Handle: http://hdl.handle.net/2078.1/105540
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Wang, Tao
%A Vandendorpe, Luc
%T Coordinate ascent based resource allocation algorithm for maximizing WSMR in downlink cellular OFDMA systems
%X This paper considers the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system, in which multiple base stations (BSs) are coordinated by a centralized resource allocation algorithm. We address the problem of maximizing the weighted sum of the minimal user rates (WSMR) of coordinated cells subject to a total power constraint at each BS. In particular, the solution of this problem corresponds to a resource allocation that guarantees similar rates to users in each cell. We propose a coordinate ascent based iterative algorithm which alternatively updates the power allocation by solving a successive set of convex optimization problems with geometric programming, as well as optimizes the subcarrier allocation by solving a linear program for each cell. We illustrate the effectiveness of the algorithm by numerical experiments.
%K Coordinate ascent
%K Resource allocation algorithm
%K Maximizing WSMR
%K Downlink cellular OFDMA systems
%K Multiple base stations
%K Convex optimization problems
%K Geometric programming
%K Subcarrier allocation
%K 2550
%G Anglais
%B 2010 IEEE 21st International Symposium on Personal, Indoor and MobileRadio Communications Workshops (PIMRC Workshops)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/74616
%R 10.1109/PIMRCW.2010.5670399
%R 10.1109/PIMRCW.2010.5670399
%* peer-reviewed
%0 Book Section
%9 Conférence invitée / Keynote
%+ Thales Communications - TCF
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Morgand, Philippe
%A Ferreol, Anne
%A Sarkis, Rémi
%A Craeye, Christophe
%A Oestges, Claude
%T Detection and location of people in emergency situations through their PMR or GSM/UMTS phones
%K ICTEAM:COMM
%G Anglais
%B Proceedings European Wireless Technology Conference
%D 2010
%U Handle: http://hdl.handle.net/2078.1/105531
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Quitin, Francois
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Diffuse Multipath Component Characterization for Indoor MIMO Channels
%X Stochastic geometry-based models have been widely adopted for modeling wireless channels. These models are parametrized based on extensive measurement campaigns, where individual propagation paths are extracted with algorithms like SAGE or RiMax. It has been observed that when extracting individual propagation paths, part of the power is not captured. This residual power is referred to as the diffuse multipath component (DMC). In this paper, the spatio-temporal characteristics of the DMC are extracted from an extensive measurement campaign. It is observed that the angular power spectrum of the DMC is not angular-white, and that the angular properties of the DMC are significantly correlated with the angular properties of the specular part of the channel. A scheme is proposed to model the diffuse part of the channel by adding diffuse properties to each cluster corresponding to the specular part of the channel. The angular properties of the diffuse part of the clusters are modeled with Von-Mises distributions, whereas the delay properties of the clusters are modeled with an exponential decaying power profiles. Finally, the polarization properties of the diffuse part of the clusters are investigated.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67379
%* peer-reviewed
%Z Quitin, F.; Horlin, F.; De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles, Brussels, Belgium Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mani, Francesco
%A Oestges, Claude
%T Evaluation of Diffuse Scattering Contribution for Delay Spread and Crosspolarization Ratio Prediction in an Indoor Scenario
%X This paper presents the results of radio channel measurements and ray tracing simulations in an indoor environment. A model for diffuse scattering is implemented in a pre-existing ray tracing tool. Simulations results show that this implementation is important to improve crosspolarization ratio prediction accuracy. For delay spread, the improvement is restricted to deep non-line-of-sight areas.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67378
%* peer-reviewed
%Z Mani, F.; Oestges, C.; ICTEAM - Electr. Eng., Univ. Catholique de Louvain, Louvain la Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Renaudin, Olivier
%A Kolmonent, Veli-Mati
%A Vainikainent, Pertti
%A Oestges, Claude
%T Impact of Correlation Matrix Estimation Accuracy on the Computation of Stationarity Intervals
%X The correlation matrix distance (CMD) is widely used to measure the stationarity of MIMO channels. The CMD measures the amount of change in the spatial structure of the MIMO channels, which can be estimated for the transmit (Tx) or receive (Rx) side but also for the full channel. Stationarity intervals can then be defined based on the CMD. In this paper, we analyze the influence of the correlation matrix estimation on the computation of stationarity intervals. More specifically, we emphasize on the quantity of data required to estimate accurately correlation matrices. Some examples are given, based on measured vehicle-to-vehicle (V2V) data.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67373
%* peer-reviewed
%Z Renaudin, O.; Oestges, C.; ICTEAM Electr. Eng., Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium Kolmonent, V.-M.; Vainikainent, P.; SMARAD Radio Sci. & Eng., Aalto Univ., Aalto, Finland
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Tao Wang
%A Vandendorpe, Luc
%T Iterative Power and Subcarrier Allocation for Maximizing WSMR in Cellular OFDMA Systems
%X We consider the resource allocation (RA) problem of maximizing the weighted sum of the minimal user rates (WSMR) of coordinated cells subject to a total power constraint at each base station (BS) in the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system. In particular, the solution of this problem corresponds to a RA that guarantees similar rates to users in each cell. We propose a coordinate ascent (CA) based algorithm which alternatively updates the power allocation by solving a successive set of convex optimization problems with a duality-based numerical algorithm, and the subcarrier allocation by solving a mixed integer linear program for each cell. The effectiveness of the algorithm is illustrated by numerical experiments.
%B 2010 8th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67359
%* peer-reviewed
%Z Tao Wang; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Oguz, Onur
%A Vandendorpe, Luc
%A Herzet, C.
%T Low complexity iterative detection in the presence of nuisance parameters
%X This work addresses the bit-wise optimal data detection problem when unknown nuisance parameters influence the observation at the receiver. For an arbitrary communications system, the optimal maximum a-posteriori detection problem is first defined as a marginalization of a joint distribution which statistically models the interaction of available sets of variables/parameters. Then, using a factor graph representation with an accompanying sum-product message passing algorithm, it is shown that the marginalization can be performed iteratively. To alleviate complexity due to the marginalization over continuous natured nuisance parameters, variational Bayesian approximation is introduced and it is shown that, if the nuisance parameters are constant for a period of time, the receiver has linear complexity.
%B 2010 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2010
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67333
%R 10.1109/ICASSP.2010.5496058
%R 10.1109/ICASSP.2010.5496058
%* peer-reviewed
%Z Oguz, O.; Vandendorpe, L.; Comm. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium Herzet, C.; INRIA Rennes Bretagne-Atlantique, Rennes, France
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T ML co-channel interference estimation from SINR measurements for multicell OFDM downlink: Bounds and performance analysis
%X We consider the downlink of a multicell OFDM system where the frequency reuse factor is 1. Base-stations cooperate and precode the symbols intended for the mobile stations (terminals) located in different cells and operating on the same frequency, in order to precompensate the co-channel interferences (CCIs). To design the precoders, the CCI coefficients have to be estimated. We assume that the mobile stations are able to estimate their SINR that they feedback to their base-station. By properly designing a perturbation signal, it is possible for the base-station to estimate the complex valued CCI coefficients from the SINRs fed back. We investigate the maximum likelihood (ML) estimation of co-channel coefficients from SINR measurements. We obtain the associated Crame r-Rao bound and the mean square error of a practical estimator. Finally a two-cells system is considered and we investigate the impact of such a co-channel estimation on the sum rate of the system when precoding is operated based on these estimates.
%B 2010 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2010
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67330
%R 10.1109/ICASSP.2010.5496016
%R 10.1109/ICASSP.2010.5496016
%* peer-reviewed
%Z Vandendorpe, L.; Louveaux, J.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Castiglione, Paolo
%A Oestges, Claude
%A Czink, Nicolai
%A Bandemer, Bernd
%A Kaltenberger, Florian
%A Paulraj, Arogyaswami
%T Multi-Link Level Simulation Model of Indoor Peer-to-Peer Radio Channels
%X This paper presents a link-simulation model for cooperative indoor communication systems at 2.4 GHz, based on empirical data. The channel simulator relies on a simple formulation, and takes into account the impact of the node mobility on fading and shadowing statistics. This implementation is then applied to the evaluation of the cooperative system performance in terms of network lifetime.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67367
%* peer-reviewed
%Z Castiglione, P.; Czink, N.; FTW (Forschungszentrum Telekommun. Wien), Vienna, Austria Oestges, C.; ICTEAM Electr. Eng., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Bandemer, B.; Paulraj, A.; Smart Antennas Res. Group, Stanford Univ., Stanford, CA, USA Kaltenberger, F.; Mobile Commun. Dept., Eurecom, Sophia-Antipolis, France
%0 Book Section
%9 Conférence invitée / Keynote
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Institut Gaspard Monge - Université Paris-Est Marne-La-Vallée
%A El Soussi, Mohieddine
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Network coding for the Multiple Access Relay channel using lattices
%X We consider the problem of two transmitters would like to communicate with a destination with the help of a half-duplex relay. In this work, we are presenting the advantages of using nested lattices for the AWGN channels. The sources map their messages using lattice code and then broadcast them to the relay and the destination. The relay receives two independent symbols at the same channel. The relay either combines the two symbols using lattice modulo and then decode or decode the two symbols separately also using modulo lattice, then forwards the new symbol to the destination. The destination tries to recover the two messages using different decoding strategies. One of the strategies is to recover two linear equations in function of the two received symbols with integer coefficients then, solve these equations to recover the two messages. The integer coefficients need to be optimally selected to reduce the noise at the receivers. The other strategy is to use successive decoding at the relay and the destination. This strategy outperforms the first when two integer coefficients are zero. The strategies are discussed and compared with the traditional DF (Decode and Forward). The simulation results show the advantages of using lattice codes and the improvement in rates for certain regimes.
%G Anglais
%B Applied Sciences in Biomedical and Communication Technologies (ISABEL), 2010 3rd International Symposium on
%D 2010
%U Handle: http://hdl.handle.net/2078.1/105281
%* peer-reviewed
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Oestges, Claude
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%T On and around the human body: results and challenges in body area networks (invited communication)
%D 2010
%K ICTEAM:COMM
%G Anglais
%B 39th IEEE Communication Theory Workshop
%C Cancun, Mexico
%8 du 10/05/2010 au 12/05/2010
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078.1/105533
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Awan, Zohaib Hassan
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T On secure transmission over parallel relay eavesdropper channel
%X We study a four terminal parallel relay-eavesdropper channel which consists of multiple independent relay-eavesdropper channels as subchannels. For the discrete memoryless case, we establish inner and outer bounds on the rate-equivocation region. For each subchannel, secure transmission is obtained through one of the two coding schemes at the relay: decoding-and-forwarding the source message or confusing the eavesdropper through noise injection. The inner bound allows relay mode selection. For the Gaussian model we establish lower and upper bounds on the perfect secrecy rate. We show that the bounds meet in some special cases, including when the relay does not hear the source. We illustrate the analytical results through some numerical examples.
%G Anglais
%B 48th Annual Allerton Conference on Communication, Control, and Computing
%D 2010
%U Handle: http://hdl.handle.net/2078/122907
%R 10.1109/ALLERTON.2010.5706998
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Zaidi, Abdellatif
%A Shamai, S.
%A Piantanida, P.
%A Vandendorpe, Luc
%T On the Capacity of a Class of Relay Channels with Orthogonal Components and Noncausal State Information at Source
%X We study the capacity of a class of state-controlled relay channels with orthogonal channels from the source to the relay and from the source and relay to the destination. The channel states are assumed to be known, non-causally, to only the source. This model is useful for relaying in the context of cognition and certain interference-aware networks. For the discrete memoryless case, we establish lower bounds on the channel capacity. For the memoryless Gaussian case, we establish lower and upper bounds on the channel capacity. The upper bound is strictly better than the cut-set upper bound, and is tight for certain special cases.
%B 2010 5th International Symposium on Wireless Pervasive Computing (ISWPC)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67405
%R 10.1109/ISWPC.2010.5483705
%R 10.1109/ISWPC.2010.5483705
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Ecole Polytech. de Louvain, Univ. Catholique de Louvain, Louvain, Belgium Shamai, S.; Dept. of EE, Technion - Israel Inst. of Technol., Haifa, Israel Piantanida, P.; Dept. of Telecommun., SUPELEC, Gif-sur-Yvette, France
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Brah, Félix
%A Vandendorpe, Luc
%T On the Lambert-W function for CDIT-based power allocation in cooperative relay networks
%X In some fading environments, there may not be a feedback link sufficiently fast to convey the full channel state information (CSI) to the transmitter. This paper considers a power allocation problem for cooperative relay networks, where the transmitter node knows only the channel distribution information (CDI). The goal is to maximize the ergodic capacity. The application of the Lambert-W function to obtain a closed-form solution for the underlying power allocation problem constitutes the principal contribution of this paper. By using the Lambert-W function, power allocation can not only be expressed in closed-form but it can also quickly be determined without resorting to complex algorithms since a number of popular mathematical softwares, including Matlab, contain the Lambert-W function as an optimization component.
%B 2010 5th International Symposium on Wireless Pervasive Computing (ISWPC)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67403
%R 10.1109/ISWPC.2010.5483735
%R 10.1109/ISWPC.2010.5483735
%* peer-reviewed
%Z Brah, F.; Vandendorpe, L.; Louvain Sch. of Eng., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Conférence invitée / Keynote
%A Awan, Zohaib Hassan
%A Zaidi , Abdellatif
%A Vandendorpe, Luc
%T On the rate-equivocation region of parallel relay eavesdropper channels
%X We consider a four terminal parallel relay-eavesdropper channel which consists of multiple independent relay-eavesdropper channels as subchannels. For the discrete memoryless case, we establish inner and outer bounds on the rate equivocation region. For each subchannel, secure transmission is obtained through one of two coding schemes at the relay: decoding-and-forwarding the source message or confusing the eavesdropper through noise injection. The inner bound allows relay mode selection. We then apply our results to study the fading Gaussian relay-eavesdropper channel. In this case, we focus on perfectly secure transmission. We establish a lower bound on the perfect secrecy rate. Furthermore, considering individual sum power constraints at source and relay, we study power adjustment among the independent subchannels. We illustrate the results through some numerical examples.
%G Anglais
%B Future Network and Mobile Summit
%D 2010
%U Handle: http://hdl.handle.net/2078/122903
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Panahandeh, Ali
%A Quitin, Francois
%A Dricot, Jean-Michel
%A Horlin, Francois
%A Oestges, Claude
%A De Doncker, Philippe
%T Orientation-free XPD and CPR Model in Outdoor-to-indoor and Indoor-to-indoor Channels
%X Compared to classical spatial MIMO wireless systems, cross-polarized MIMO systems are an interesting way to reduce equipment size while reducing the inter-antenna correlation. Cross-Polar Discrimination (XPD) and Co-Polar Ratio (CPR) are two important parameters describing multi-polarized channels. In this paper, the behavior of these parameters is investigated for different observation scales. In order to overcome the ambiguity of the orientation of the receive antenna, the overall horizontal polarization is considered. A measurement campaign has been performed in both Outdoor-to-Indoor and Indoor-to-Indoor scenarios, at a frequency of 3.5GHz. Small-scale variations of XPD and CPR are analyzed in different spatial positions. The distance-related and large-scale variations of XPD and CPR are also investigated and an orientation-free model is deduced.
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67375
%* peer-reviewed
%Z Panahandeh, A.; Quitin, F.; Dricot, J.M.; Horlin, F.; De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium Oestges, C.; Microwave Lab., Univ. catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Sanchez, Fernando
%A Bandemer, Bernd
%A Matz, Gerald
%A Oestges, Claude
%A Kaltenberger, Florian
%A Czink, Nicolai
%T Performance of transmission-time optimized relaying schemes in real-world channels
%X The deployment of relay stations has been proposed as a practical means to increase spectral efficiency in wireless networks. In this paper, we compare the achievable data rates of several relaying schemes using measurements at 2.45 GHz. We investigate the decode-and-forward relay schemes described by Nabar et al., which we extend by additionally optimizing transmit durations. At the transmitters, we distinguish between the availability of instantaneous channel state information and average channel SNR information. Our data analysis indicates that (i) the deployment of relays can improve ergodic data rate at least twofold, (ii) instantaneous channel knowledge enables at most 8.7% increase in spectral efficiency over average channel knowledge, and (iii) relay selection has a large impact on the performance of cooperative networks.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67368
%* peer-reviewed
%Z Gonza lez, F.S.; Czink, N.; FTW Telecommun. Res. Center, Vienna, Austria Bandemer, B.; Stanford Univ., Stanford, CA, USA Matz, G.; Inst. of Commun. & RF Eng., Vienna Univ. of Technol., Vienna, Austria Oestges, C.; Univ. catholique de Louvain, Louvain la Neuve, Belgium Kaltenberger, F.; Eurecom, Sophia Antipolis, France
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%T Power-Efficient Estimation in Sensor Networks with Correlated Data: Perfect and Imperfect CSI
%G Anglais
%B Communication, Control, and Computing (Allerton), 2010 48th Annual Allerton Conference on
%D 2010
%U Handle: http://hdl.handle.net/2078.1/78748
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Tao Wang
%A Vandendorpe, Luc
%T Resource allocation for maximizing weighted sum min-rate in downlink cellular OFDMA systems
%X This paper considers the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system, in which multiple base stations (BS) are coordinated by a centralized resource allocation algorithm. We address the problem of maximizing the weighted sum min-rate (WSMR) subject to a total power constraint at each BS, in terms of jointly optimizing coordinated BSs' subcarrier and power allocation. In particular, this problem leads to a resource allocation that guarantees similar rates to users in each cell. An iterative algorithm is proposed to optimize subcarrier and power allocation alternatively, so that the WSMR keeps increasing until convergence. In each iteration, the subcarrier allocation is updated by solving a mixed integer linear programming problem for each cell, while the power allocation is updated by solving a successive set of convex optimization problems with an algorithm based on Karush-KuhnTucker conditions. The effectiveness of the algorithm is illustrated by numerical experiments.
%B ICC 2010 - 2010 IEEE International Conference on Communications
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67384
%R 10.1109/ICC.2010.5501904
%R 10.1109/ICC.2010.5501904
%* peer-reviewed
%Z Tao Wang; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ University of Pisa - Telecommunications Dpt
%A Andreotti, Riccardo
%A Stupia, Ivan
%A Giannetti, Filippo
%A Lottici, Vincenzo
%A Vandendorpe, Luc
%T Resource allocation in OFDMA underlay cognitive radio systems based on Ant Colony Optimization
%X This paper deals with dynamic resource allocation problem for OFDMA-based cognitive radio systems. The proposed solution is specifically tailored for a secondary base stations (SBS) transmitting to secondary users (SUs) over the same bands of the licensed primary users (PUs) in underlay fashion. The downlink transmission goodput is thereby maximized while keeping the interference on the PUs within a tolerable range. The NP-hard goodput maximization problem is tackled resorting to an efficient meta-heuristic algorithm based on Ant Colony Optimization (ACO) framework.
%K Cognitive radio
%K Communication complexity
%K Ant colony optimization
%K Dynamic resource allocation problem
%K Secondary base station
%K Secondary users
%K Primary users
%K Downlink transmission goodput
%K Interference
%K NP-hard goodput maximization problem
%K Meta-heuristic algorithm
%K Frequency division multiple access
%K Interference
%K OFDM modulation
%K Optimisation
%K Radio links
%K Resource allocation
%K OFDMA
%K Underlay cognitive radio system
%K 2556
%G Anglais
%B 2010 IEEE 11th International Workshop on Signal Processing Advances inWireless Communications (SPAWC 2010)
%D 2010
%U Handle: http://hdl.handle.net/2078.1/74617
%R 10.1109/SPAWC.2010.5671014
%R 10.1109/SPAWC.2010.5671014
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Montenegro Villacieros, Belén
%A Oestges, Claude
%A Vanhoenacker-Janvier, Danielle
%A Prieto-Cerdeira, Roberto
%A Martellucci, Antonio
%T Review and Update of Mobile Data Processing for the Land Mobile Satellite Channel Modelling
%X In this paper, measurements from various narrowband and wideband Land Mobile Satellite (LMS) and Satellite Aeronautical experimental campaigns that have been homogeneously pre-processed and re-analysed in order to derive concise statistical results for submission to ITU-R statistical databanks. A number of problems in the processing steps were identified and various methods were applied to minimise the effect on the results, for instance, the calibration of the Line of Sight (LOS) level, the accuracy of position and attitude of transmitter and receiver or problems with bandwidth and frequency synchronisation/drifts for wideband measurements.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 4th European Conference on Antennas and Propagation
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67377
%* peer-reviewed
%Z Montenegro-Villacieros, B.; Oestges, C.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain la Neuve, Belgium Prieto-Cerdeira, R.; Martellucci, A.; ESA/ESTEC, Noordwijk, Netherlands
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A Endeshaw, T.
%A Chalise, B.K.
%A Vandendorpe, Luc
%T Robust Sum Rate Optimization for the Downlink Multiuser MIMO Systems: Worst-case Design
%X This paper considers the problem of jointly designing the precoders for the downlink multiuser multiple-input multiple-output (MIMO) systems where imperfect channel state information (CSI) is available at the base station (BS). The multi-antenna users are assumed to employ the linear minimum-mean-square-error (MMSE) receivers. Our objective is to maximize the achievable sum rate under a total BS power constraint and provide robustness against the channel uncertainties. We apply the familiar worst-case performance optimization approach, which in our case turns to be the problem of maximizing the worst-case sum rate constrained with the total BS power. The problem is examined as follows. We first reformulate the expression for the MMSE matrix so that it is conveniently utilized for the worst-case sum rate maximization problem. Then, we solve the resulting robust design problem efficiently by employing the existing mean-square-error (MSE) uplink/downlink duality approach. Computer simulations verify the robustness of the proposed design when compared to the non-robust/naive design.
%B ICC 2010 - 2010 IEEE International Conference on Communications
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67385
%R 10.1109/ICC.2010.5501825
%R 10.1109/ICC.2010.5501825
%* peer-reviewed
%Z Endeshaw, T.; Chalise, B.K.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain La Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM - Institute for Information and Communication. Technologies, Electronics and Applied Mathematics
%A El Soussi, Mohieddine
%A Zaidi, Abdellatif
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Sum-rate Optimized Power Allocation for the OFDM Multiple Access Relay Channel
%X We/sup 1/ consider transmission over a set of parallel MARCs (multiple-access relay channel) based on the OFDM (Orthogonal Frequency Division Multiplexing) modulation. Two users communicate to a common destination (D) with the help of a relay (R) over a set of parallel channels. The relay operates in decode and forward (repetition coding type) and half duplex modes. The problem considered is the maximization of the total sum rate at the destination by optimal allocation of the power to the different carriers for the users and the relay. The problem is investigated for a sum power constraint. We show that for each carrier only one user should be relayed at most, and the other user should communicate over the direct link. Unlike the classical MAC, we show that there exist cases where both users should share the same carrier to transmit symbols and this increases the rate. For these carriers, there exist, considering both the relay and the destination, four possible decoding orders. As the problem is non-convex and non-linear, it is not easy to a-priori select the best decoding order (at the relay and the destination), and which user should be relayed. An algorithm is proposed to solve the global optimization problem. The theoretical results are illustrated by computational results.
%B 4th International Symposium on Communications, Control and Signal Processing (ISCCSP)
%I IEEE
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67423
%R 10.1109/ISCCSP.2010.5463433
%R 10.1109/ISCCSP.2010.5463433
%* peer-reviewed
%Z El Soussi, M.; Zaidi, A.; Louveaux, J.; Vandendorpe, L.; Louvain Sch. of Eng., Commun. & Remote Sensing Lab., Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mallat, Achraf
%A Gérard, Pierre
%A Drouguet, Maxime
%A Keshmiri, Farshad
%A Oestges, Claude
%A Craeye, Christophe
%A Flandre, Denis
%A Vandendorpe, Luc
%T Testbed for IR-UWB based ranging and positioning: Experimental performance and comparison to CRLBs
%X In this paper we describe a testbed for impulse radio ultra wideband based ranging and positioning. We show the characteristics of the generated, transmitted and received pulses. We consider both the maximum likelihood estimator and a threshold-based estimator for the estimation of the time of arrival. We measure the variances for ranging and positioning and compare them to the Cramer-Rao lower bounds for range and position estimation. We discuss the impact of both false multipath component detection and false sidelobe detection on the estimation accuracy. The obtained variances are close to the Cramer-Rao lower bounds when the mainlobe of the first multi-path component is detected. In realistic multipath environments we can use a threshold-based time of arrival estimator in order to detect the first multipath component which may be missed by the maximum likelihood estimator. We show also that the errors on positioning due to false multipath component and sidelobe detection can be highly mitigated by increasing the number of receivers. For a radiated energy of 8.1 pJ and a distance of 5 meters between the transmit and receive antennas, the obtained accuracy is in the order of one centimeter.
%K ICTEAM:COMM
%K ICTEAM:CIRC
%G Anglais
%B Proceedings 5th International Symposium on Wireless Pervasive Computing
%D 2010
%U Handle: http://hdl.handle.net/2078.1/67404
%R 10.1109/ISWPC.2010.5483707
%* peer-reviewed
%Z Mallat, A.; Gerard, P.; Drouguet, M.; Keshmiri, F.; Oestges, C.; Craeye, C.; Flandre, D.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Giannetti, F.
%A Lottici, V.
%A Vandendorpe, Luc
%T A novel exponential link error prediction method for OFDM systems
%X Coded multicarrier techniques combined together with link resources adaptation algorithms are the key technologies toward efficient high-data-rate communications over wireless fading channels. This paper contributes with a novel accurate yet simple method to predict at the transmitter the link performance of bit-interleaved coded (BIC) orthogonal frequency division multiplexing (OFDM) links, which offers appealing features when compared with conventional techniques. Its effectiveness is confirmed through extensive simulation results obtained over typical wireless channel environments. © 2009 Springer-Verlag.
%K Adaptation algorithms
%K Wireless channel environments
%K Wireless fading channels
%K Carrier communication
%K Communication channels (information theory)
%K Fading (radio)
%K Fading channels
%K Frequency allocation
%K Multicarrier modulation
%K Orthogonal functions
%K Telecommunication systems
%K Coded multicarrier
%K Orthogonal frequency division multiplexing
%K Conventional techniques
%K Extensive simulations
%K Key technologies
%K Link error predictions
%K Link performance
%K OFDM systems
%K SIMPLE method
%G Anglais
%B 7th International Workshop on Multi-Carrier Systems and Solutions, MC-SS 2009
%D 2009
%U Handle: http://hdl.handle.net/2078.1/138713
%0 Book Section
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Giannetti, F.
%A Lottici, V.
%A Vandendorpe, Luc
%T A novel link performance prediction method for coded MIMO-OFDM systems
%X Coded multi-antenna and multi-carrier techniques combined together with link resources adaptation algorithms are the key technologies toward efficient high-data-rate communications over wireless fading channels. The practicability of this concept, however, requires that the transmitter can perform accurate and simple evaluation of the actual link performance. This paper contributes with a novel method specifically developed to predict the link performance of bit-interleaved coded MIMOOFDM links, which offers improved accuracy at the price of lower complexity when compared with conventional techniques. Its effectiveness is confirmed through extensive simulation results obtained over typical wireless channel environments. © 2009 IEEE.
%K Adaptation algorithms
%K Multi-antenna
%K Multicarrier technique
%K Novel methods
%K Wireless channel environments
%K Wireless fading channels
%K Communication channels (information theory)
%K Fading (radio)
%K Fading channels
%K MIMO systems
%K Orthogonal frequency division multiplexing
%K Conventional techniques
%K Telecommunication systems
%K Turbo codes
%K Wireless networks
%K Data-rate communication
%K Extensive simulations
%K Key technologies
%K Link performance
%K Lower complexity
%K MIMO-OFDM
%K MIMO-OFDM systems
%G Anglais
%B Wireless Communications and Networking Conference, 2009. WCNC 2009. IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/138709
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Mani, Francesco
%A Oestges, Claude
%T A ray based indoor propagation model including depolarizing penetration
%X This paper presents the results of radio channel measurements and ray tracing simulations for an indoor propagation environment. A model for depolarizing penetration is combined with a ray tracing tool to account for depolarization.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 3rd European Conference on Antennas and Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67609
%* peer-reviewed
%Z Mani, F.; Oestges, C.; Microwave Lab., Univ. catholique de Louvain, Louvain la Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Achievable rates for the Gaussian relay interferer channel with a cognitive source
%X A relay interferer channel consists of the classic relay channel with an additional source of interference. A three- terminal full-duplex Gaussian relay interferer channel with a cognitive source is analyzed. Each of the relay node and the destination node experiences on its link an additive Gaussian outside interference, in addition to additive noise. Only the source node, referred to as being the cognitive encoder, knows the interferences, in a non-causal manner. We first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. For each of these two models, we establish a lower bound on the channel capacity. The coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. The results reveal that, by opposition to carbon copying onto dirty paper and its root Costa's initial dirty paper coding (DPC), it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67589
%R 10.1109/ICC.2009.5198689
%R 10.1109/ICC.2009.5198689
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Ecole Polytech. de Louvain, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Sneessens, H.H.
%A Vandendorpe, Luc
%A Laneman, J.N.
%T Adaptive compress-and-forward relaying in fading environments with or without Wyner-Ziv coding
%X Compress-and-Forward is a protocol for transmission over relay networks in which the relay forwards a compressed version of the signal it observes. The compression method used by the relay is source coding with side information, i.e. Wyner-Ziv coding, since the destination can use the signal it receives directly from the source as side information. This paper addresses the case of a wireless relay network with orthogonal transmissions from the source and the relay terminals; we show that when the transmitters have no instantaneous channel state information the optimal compression parameters often make Wyner-Ziv coding reduce to conventional source compression, i.e. compression that does not take into account the side information available at the destination. This result simplifies the implementation of the CF protocol in the case we consider, since it shows that in several situations one can use more convenient compression methods without significant performance loss.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67588
%R 10.1109/ICC.2009.5198699
%R 10.1109/ICC.2009.5198699
%* peer-reviewed
%Z Sneessens, H.H.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Louveaux, Jérôme
%A Kalakech, Ali
%A Guenach, M.
%A Maes, Joëlle
%A Peeters, Marie-Rose
%A Vandendorpe, Luc
%T An SNR-assisted crosstalk channel estimation technique
%X In this paper, we present a new method to estimate the crosstalk channels in VDSL systems, allowing to implement well-known pre-compensation schemes. As opposed to previously presented methods, this estimation only requires minimal changes to the current standard and equipments. It is based on the concept of adding small, controlled, perturbations to the transmitted signal and observing the related changes to the SNR at the receiver. It is shown in this paper that, based on a limited amount of SNR measurements from the receivers, it is possible to accurately estimate the crosstalk channels, both in amplitude and phase.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67590
%R 10.1109/ICC.2009.5198739
%R 10.1109/ICC.2009.5198739
%* peer-reviewed
%Z Louveaux, J.; Kalakech, A.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Ikhlef, Aissa
%A Louveaux, Jérôme
%T An enhanced MMSE per subchannel equalizer for highly frequency selective channels for FBMC/OQAM systems
%X In this paper the problem of equalization for filter bank multicarrier modulation based on offset OQAM (FBMC/OQAM) is investigated. Existing equalizers for FBMC/OQAM do not completely cancel intercarrier interference (ICI) and hence some ICI remains even after equalization. To cope more efficiently with ICI, we propose a two stage MMSE (TS-MMSE) equalizer. The first stage consists in applying an MMSE equalizer and taking some preliminary decisions, then subsequetly using these decisions to remove the term corresponding to ICI from the received signal for each subchannel. The resulting signal from the first stage has its ICI practically removed (up to channel estimation errors and decision errors) and is therefore corrupted only by intersymbol interference (ISI) and additive noise. In the second stage we apply an MMSE equalizer which copes only with ISI. The proposed two stage MMSE equalizer has shown better performance compared to the classical MMSE one. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.
%B 2009 IEEE 10th Workshop on Signal Processing Advances in Wireless Communications (SPAWC)
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67601
%R 10.1109/SPAWC.2009.5161772
%* peer-reviewed
%Z Ikhlef, A.; Louveaux, J.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain Place du Levant, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Roy, Stéphane
%A Liu, Lingfeng
%A Oestges, Claude
%A De Doncker, Philippe
%T An ultra-wideband SAGE algorithm for body area networks
%X Body area networks (BANs) consist of a set of bio-sensors placed on the human body and measuring some physiological or contextual information. The data are collected by some central devices located on the body or in the surrounding environment of the body via single or multi-hop transmissions. Typical applications include the real-time monitoring of heart activity blood pressure, breathing rate, or skin temperature, for the purpose of diagnostics or generating automatic calls for emergency.
%K ICTEAM:COMM
%G Anglais
%B Proceedings International Conference on Electromagnetics in Advanced Applications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67548
%R 10.1109/ICEAA.2009.5297364
%* peer-reviewed
%Z Van Roy, S.; Lingfeng Liu; De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium Oestges, C.; Microwave Lab., Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Fort, Andrew
%A Liu, Lingfeng
%A Keshmiri, Farshad
%A De Doncker, Philippe
%A Oestges, Claude
%A Craeye, Christophe
%T Analysis of wave propagation including shadow fading correlation for BAN applications
%X The presentation of slide shows that the decrease of rho /sub 12,13/ as d/sub 23/ increases is observed in the measurement results. A simple on-body propagation model indicates that the limited number of MPCs in on-body propagation can still show correlation and decorrelation of propagation channels. The model needs to be improved, e.g. include a more accurate arm/body scattering model.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 2nd IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67567
%* peer-reviewed
%Z Liu, L.; Keshmiri, F.; Oestges, C.; Craeye, C.; Univ. Catholique de Louvain, Louvain-La-Neuve, Belgium Fort, A.; Vrije Univ. Brussels, Brussels, Belgium De Doncker, P.; Univ. Libre de Bruxelles, Brussels, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Liu, Lingfeng
%A Van Roy, Stéphane
%A De Doncker, Philippe
%A Oestges, Claude
%T Azimuth radiation pattern characterization of omnidirectional antennas near a human body
%X In this paper, measurements of radiation patterns for an antenna close to the human body at different frequencies are presented. An analytical channel model based on multiple cylinder scattering is proposed. Measurement results and simulations are compared and highlight the impact of body shadowing and arm scattering on the modification of the antenna azimuth radiation pattern.
%K ICTEAM:COMM
%G Anglais
%B Proccedings International Conference on Electromagnetics in Advanced Applications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67545
%R 10.1109/ICEAA.2009.5297393
%* peer-reviewed
%Z Lingfeng Liu; Van Roy, S.; Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Giannetti, F.
%A Lottici, V.
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T BICMB-OFDM link resource adaptation
%X An efficient and flexible air interface is the necessary condition for enabling high data rates next generation wireless systems. A practical answer to this need consists in exploiting channel state information at the transmitter for an adaptive and efficient use of the available radio link resources. This paper contributes with a novel strategy for the allocation of the subcarrier transmit power in the case of a wireless system featuring: i) bit-interleaved coded modulation (BICM); ii) orthogonal frequency division multiplexing (OFDM); iii) multiple antenna profile (MIMO). The proposed power-allocation algorithm aims at maximizing the so-called goodput performance metric for packet transmissions employing automatic repeat request (ARQ) schemes. In addition, it is also proven to be near-optimum in maximizing the input/output mutual information of the MIMO-OFDM subchannels. Numerical simulations over typical wireless indoor scenarios confirm the effectiveness of the procedure when applied in the context of MIMO-BICM-OFDM systems. ©2009 IEEE.
%K Automatic-repeat-request schemes
%K Mutual informations
%K Next generation wireless systems
%K Novel strategies
%K Numerical simulation
%K OFDM systems
%K Packet transmissions
%K Power allocations
%K Subcarrier
%K Subchannels
%K Transmit power
%K Bit interleaved coded modulation
%K Wireless systems
%K Computer simulation
%K Error correction
%K Frequency allocation
%K MIMO systems
%K Multiplexing
%K Orthogonal frequency division multiplexing
%K Pulse code modulation
%K Radio broadcasting
%K Radio links
%K Channel state information at the transmitters
%K Wireless telecommunication systems
%K Flexible air interfaces
%K Goodput performance
%K High data rate
%K Input/output
%K MIMO-OFDM
%K Multiple antenna
%G Anglais
%B Proc. IEEE International Conference on Communications (ICC 2009)
%D 2009
%U Handle: http://hdl.handle.net/2078.1/137031
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Mallat, Achraf
%A Oestges, Claude
%A Vandendorpe, Luc
%T CRBS for UWB multipath channel estimation: impact of the overlapping between the MPCs on MPC gain and TOA estimation
%X In this paper we study the impact of the overlapping between neighboring MPCs (multipath component) on the performance of channel estimation. We consider IR-UWB (impulse radio) signals, and the IEEE802.15.3a and IEEE802.15.4a UWB channel models. We show that for a pulse width (PW) sufficiently smaller than the average MPC rate of arrival (ROA) the probability to have more than three overlapping MPCs is relatively small. We derive the CRBs (Cramer Rao bound) for the joint estimation of the MPC gain and TOA (time of arrival) in the case of up to three overlapping MPCs. We compute also the average CRBs. We show that the CRBs obtained by averaging more than 80% of possible cases of the channel, are very close to the bounds obtained under the non-overlapping assumption (NOLA).
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67591
%R 10.1109/ICC.2009.5198871
%* peer-reviewed
%Z Mallat, A.; Oestges, C.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Mallat, Achraf
%A Vandendorpe, Luc
%T CRBS for the joint estimation of TOA and AOA in wideband MISO and MIMO systems: comparison with SISO and SIMO systems
%X We derive the CRBs (Cramer Rao bound) for the joint estimation of the TOA (time of arrival) and the AOA (angle of arrival) in wideband (WB) MISO (multiple input single output) and MIMO (multiple input multiple output) systems. We consider both cases of orthogonal and non-orthogonal transmitted signals. We compare the CRBs obtained in SISO (single input single output), SIMO (single input multiple output), MISO and MIMO systems under the assumption that the total transmitted energy is the same for all systems. We show that SIMO and MIMO are equivalent for TOA estimation, and MISO and SISO as well when the transmitted signals are orthogonal. For non-orthogonal signals, MIMO is better than SIMO, and MISO is better than SISO when the received signals are constructive. For AOA estimation, we show that MIMO is better than SIMO and SIMO is better than MISO when the transmitted signals are orthogonal. For non-orthogonal signals, MIMO is much better when the received signals are constructive. The CRBs obtained for non- orthogonal signals are very sensitive to the angle. Numerical results obtained in a typical scenario are provided.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67593
%R 10.1109/ICC.2009.5198870
%R 10.1109/ICC.2009.5198870
%* peer-reviewed
%Z Mallat, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Czink, Nicolai
%A Bandemer, Bernd
%A Paulraj, Arogyaswami
%T Capacity Performance of Outdoor-to-Indoor Relay Schemes in Measured Radio Channels
%X In this paper, the capacity of several outdoor-to-indoor relay schemes has been investigated using real-world measurements at 2.45 GHz. The considered scenario encompasses an outdoor base station, possibly using multiple antennas, communicating via two hops to distributed single antenna terminals located inside a building. The single-antenna relays are located along the so-called best wall. Capacity results show that in most cases, relaying techniques increase the capacity, even when constraining the global power expense of the network. Considering a combining scheme using the source-to-destination in addition to the relay link does not bring huge benefits for the measured outdoor-to-indoor channels. The best performance is obtained in a relay-and-forward scheme using multiple cooperative relays.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 20th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67435
%R 10.1109/PIMRC.2009.5450275
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Czink, N.; Forschungszentrum Telekommunikation Wien (ftw.), Vienna, Austria Bandemer, B.; Paulraj, A.; Smart Antennas Res. Group, Stanford Univ., Stanford, CA, USA
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Renaudin, Olivier
%A Kolmonen, Veli-Matti
%A Vainikainen, Pertti
%A Oestges, Claude
%T Car-to-car channel models based on wideband MIMO measurements at 5.3 GHz
%X In this paper, we describe measurement results of 30 * 30 multiple-input multiple-output (MIMO) car-to-car (C2C) radio channels at 5.3 GHz in four environments: on a campus, on a highway, in urban and sub-urban areas. We first investigate the validity of the wide-sense stationarity (WSS) assumption by using the correlation matrix distance (CMD), which is an earlier introduced metric for characterizing the MIMO channel non-stationarity. Finally, we develop a statistical 20 MHz bandwidth channel model in the highway environment, including tap amplitude statistics and inter-tap correlation matrices. The small-scale fading was found to be best fitted by both the Nakagami and Weibull distributions.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 3rd European Conference on Antennas and Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67614
%* peer-reviewed
%Z Renaudin, O.; Oestges, C.; Microwave Lab., Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Quitin, Francois
%A Oestges, Claude
%A Horlin, Francois
%A De Doncker, Philippe
%T Clustered channel characterization for indoor polarized MIMO systems
%X A cluster-based channel model is presented that includes polarization characteristics. Measurements have been carried out in an indoor environment at 3.6 GHz using a dual-polarized transmitter and a tri-polarized receiver. Individual propagation paths are extracted using the SAGE algorithm, and a cross-polar discrimination (XPD) per ray is defined. Clusters are identified in the co-elevation-azimuth-delay domain, with an automatic clustering algorithm. The cluster properties are investigated and polarization characteristics are identified on a per-cluster basis. Finally, the obtained model is simulated and extraction-independent parameters are compared with experimental parameters for validation.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 20th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67436
%R 10.1109/PIMRC.2009.5450268
%* peer-reviewed
%Z Quitin, F.; Horlin, F.; De Doncker, P.; OPERA Dept., Univ. Libre de Bruxelles (ULB), Brussels, Belgium Oestges, C.; Microwave Lab., Univ. catholique de Louvain (UCL), Louvain-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Brah, Félix
%A Vandendorpe, Luc
%T Constrained ergodic rates maximization for mobile WiMAX with statistical channel information
%X In some fading environments, there may not be a feedback link sufficiently fast to convey the full channel state information (CSI) to the transmitter. This paper considers resource allocation strategies for downlink multiuser mobile WiMAX systems, where the base station knows only the channel distribution information (CDI), but has no knowledge of the instantaneous channel realization. The base station uses CDI to assign subchannels and allocate power to users with the objective to maximize the ergodic weighted sum rate while satisfying minimum rate, long-term fairness and power constraints. We solve the underlying constrained optimization problem using the Lagrange dual decomposition framework. The proposed method has a complexity of O(KM) for K users and M subchannels. Simulation results are provided to compare the performance of this method with other allocation schemes and to illustrate the trade-off between maximized weighted sum rate and the constraints.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67592
%R 10.1109/ICC.2009.5198847
%R 10.1109/ICC.2009.5198847
%* peer-reviewed
%Z Brah, F.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Czink, Nicolai
%A Bandemer, Bernd
%A Castiglione, Paolo
%A Kaltenberger, Florian
%A Paulraj, Arogyaswami
%T Experimental Characterization of Indoor Multi-Link Channels
%X In this paper, an empirical model of the indoor distributed channel is presented. In particular, the shadowing and fading statistics are extracted from experimental data at 2.45 GHz in stationary and mobile scenarios. Highlights of the paper include a separate model for static and dynamic shadowing, a model for shadowing correlation, as well as a single analytical distribution of small-scale fading for various types of indoor node mobility.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 20th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67433
%R 10.1109/PIMRC.2009.5450278
%* peer-reviewed
%Z Oestges, C.; Kaltenberger, F.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium Czink, N.; Castiglione, P.; Forschungszentrum Telekommunikation Wien (ftw.), Vienna, Austria Bandemer, B.; Paulraj, A.; Smart Antennas Res. Group, Stanford Univ., Stanford, CA, USA
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ ULB - OPERA
%A Liu, Lingfeng
%A De Doncker, Philippe
%A Oestges, Claude
%T Fading correlation measurement and modeling on the front side of a human body
%K ICTEAM:COMM
%G Anglais
%B Proceedings 3rd European Conference on Antennas and Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/88439
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Endeshaw, T.
%A Chalise, B.K.
%A Vandendorpe, Luc
%T MSE uplink-downlink duality of MIMO systems under imperfect CSI
%X This paper addresses the mean square error (MSE) uplink/downlink duality for the multiple input multiple output (MIMO) systems where imperfect channel state information (CSI) is available at the base station (BS) and mobile stations (MSs). The channel is modeled by incorporating antenna correlation at the BS. In contrast to the perfect CSI case where instantaneous MSE duality is considered, the average mean square error (AMSE) duality is exploited. To show the application of our AMSE duality we consider the minimum mean square error (MMSE) transceiver design for the downlink multiuser MIMO systems. Our objective is to minimize the sum MSE constrained with a total BS power and provide robustness against channel uncertainties. In the uplink channel, the power allocation part of this problem is formulated as a geometric program (GP). Based on the solution of GP and the AMSE duality analysis, we propose an iterative algorithm that performs optimization alternatively between the uplink and the downlink channels. The convergence behavior of the proposed algorithm is studied. Computer simulations verify the robustness of the proposed design when compared to the non-robust/naive design.
%B 2009 3rd IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP 2009)
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67512
%R 10.1109/CAMSAP.2009.5413251
%R 10.1109/CAMSAP.2009.5413251
%* peer-reviewed
%Z Endeshaw, T.; Chalise, B.K.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Montenegro Villacieros, Belén
%A Vanhoenacker-Janvier, Danielle
%T Modeling propagation into collapsed buildings for radio-localization-based rescue search missions
%X The retrieval of people trapped in buildings in fire or partially destroyed is a priority for rescue teams. Given the widespread use of mobile phones by the general public, an innovative idea to retrieve victims or to track rescue teams consists in capturing, via an antenna array acting as subrogated base station, the signals transmitted by cell phones (even if these are in idle mode). Real-time postprocessing then allows localizing the victim using a robust localization algorithm. The receive antenna array may be mounted under a helicopter for a first rough localization, while a second step involves a pedestrian rescue team equipped with portable versions of the same antenna array, providing in real-time localization data of the victim. In order to evaluate the performance of localization algorithms, a precise channel characterization is however required. Collapsed building structures constitute a very complex environment, for which no model exists so far. Also, there is a huge variety of possible scenarios because many different material can be involved; the electromagnetic properties of any given material strongly depends on the structure, humidity, compression, etc., so that the values of permittivity and conductivity are hardly known with precision; and the shape and dimensions of each rubble is highly variable. The goal of the present communication is to propose a channel model to predict the propagation characteristics between an outdoor unit and a buried terminal.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Symposium on Antennas & Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67595
%R 10.1109/APS.2009.5172252
%* peer-reviewed
%Z Oestges, C.; Montenegro-Villacieros, B.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%A Kotagiri, S.P.
%A Laneman, J.N.
%T Multiaccess channels with state known to one encoder: another case of degraded message sets
%X We consider a two-user state-dependent multiaccess channel in which only one of the encoders is informed, non-causally, of the channel states. Two independent messages are transmitted: a common message transmitted by both the informed and uninformed encoders, and an individual message transmitted by only the uninformed encoder. We derive inner and outer bounds on the capacity region of this model in the discrete memoryless case as well as the Gaussian case. Further, we show that the bounds for the Gaussian case are tight in some special cases.
%B 2009 IEEE International Symposium on Information Theory - ISIT
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67584
%R 10.1109/ISIT.2009.5205986
%R 10.1109/ISIT.2009.5205986
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Ecole Polytech. de Louvain, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Ikhlef, Aissa
%A Louveaux, Jérôme
%T Per subchannel equalization for MIMO FBMC/OQAM systems
%X In multiple-input multiple-output (MIMO) filter bank multicarrier modulation (FBMC) systems, the frequency selective transmission channel causes intersymbol interference (ISI), and intercarrier interference (ICI), and using multiple antennas creates interantenna interference (IAI). To mitigate these distortions we derive an MMSE equalizer which takes into account all of them. Assuming spatial multiplexing is used, we propose a successive interference cancellation (SIC) and Ordered SIC (OSIC) techniques to extract the transmitted streams. In order to further improve the performance we also introduce a two stage OSIC (TSOSIC) technique. Simulation results confirm the effectiveness of the proposed techniques over the classical one tap equalizer.
%B 2009 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (PacRim)
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67570
%R 10.1109/PACRIM.2009.5291308
%* peer-reviewed
%Z Ikhlef, A.; Louveaux, J.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%+ Alcatal Lucen Bell Labs - Fixed Access, Antwerp
%A Guenach, M.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%A Whiting, P.
%A Maes, J.
%A Peeters, M.
%T Performance analysis of the signal-to-noise ratio assisted crosstalk channel estimation for DSL systems
%X In this paper we investigate the tracking performance of the downstream (DS) crosstalk (XT) channel estimation based on the reported signal to noise ratio (SNR), in particular for digital subscriber line (DSL) systems. Aiming to its simplicity, the SNR-assisted XT estimation, has been recognized in ITU as a backward compatible method that does not require any change in the very high speed digital subscriber line 2 (VDSL2) standard. This low complex algorithm can be used for XT channel estimation in dynamic spectrum management (DSM) techniques today. The algorithm as proposed recently, relies on sending perturbing signals on the victim lines (VLs) and reporting the SNRs by those lines to acquire the crosstalk channel from some disturber line (DL) to the VLs. We generalize this concept to include full startup, tracking and joining scenarios as well as the impact of different perturbation signal choices. Simulation results reveal that starting from no crosstalk precompensation, and updating a precoder matrix based on the DS crosstalk channel estimates, the far-end crosstalk (FEXT) free SNR can be reached in few iterations (36 SNR measurements for the four lines case). ©2009 IEEE.
%K Backward compatible
%K Pre-compensation
%K Precoder matrix
%K Simulation result
%K Tracking performance
%K Very high speed digital subscriber line 2
%K Acoustic intensity
%K Computer crime
%K Crosstalk
%K Dielectric relaxation
%K DSL
%K Channel estimate
%K Estimation
%K Mobile telecommunication systems
%K Modems
%K Signal to noise ratio
%K Telephone lines
%K Transmitters
%K Channel estimation
%K Complex algorithms
%K Digital subscriber line systems
%K DSL systems
%K Dynamic spectrum management
%K Far end crosstalk
%K Performance analysis
%K Perturbation signals
%G Anglais
%B Proc. 2009 IEEE International Conference on Communications (ICC 2009)
%D 2009
%U Handle: http://hdl.handle.net/2078.1/137032
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Performance evaluation of a sign-error-based iterative precoder for crosstalk cancelation in DSL systems
%X In this paper, we present some theoretical performance evaluation of the crosstalk precancelation method presented in [1] for DSL systems. This algorithm uses a limited feedback from the different receivers, returning only the (complex) sign of the error on the detected symbols. It updates the precoder iteratively based on this information and on the knowledge of the transmitted symbols. Very little simulation results had been presented in [1]. Here we first propose a slightly modified and simplified version of the algorithm which is significantly less complex. We derive approximate performance expressions for this modified version and compare them to simulation results, showing a very good match. It is then shown how these results can be used to set the different parameters of the method. © EURASIP, 2009.
%K DSL systems
%K Limited feedback
%K Performance evaluation
%K Precoders
%K Theoretical performance
%K Algorithms
%K DSL
%K Signal processing
%K Crosstalk
%G Anglais
%B Proc. 17th European Signal Processing Conference, EUSIPCO 2009
%D 2009
%U Handle: http://hdl.handle.net/2078.1/137043
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Chambers, Pat
%A Oestges, Claude
%T Performance of a leakage-based precoded downlink multi-user MIMO scheme using measured channels
%X A novel low complexity multi-user MIMO downlink architecture has recently been proposed in literature. While this system seeks to palliate the limitation, imposed by some linear precoders in the absence of scheduling, that the total number of users' antennas be less than the number of base-station antennas, the system does not entirely null-out multi-user interference. The system was originally designed using complex Gaussian distributed random channel matrices as a model for the wireless channels and, as a result of this, a more experimentally focused assessment of system performance is offered in this work. It is shown that relative channel energy differences can characterise the BER performance and the eigenvalue response of the system model at low SNR. The effect of high SNR on the eigenvalue response of both measured and randomly generated channels is also highlighted.
%K ICTEAM:COMM
%G Anglais
%B Proceedings Loughborough Antennas & Propagation Conference
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67533
%R 10.1109/LAPC.2009.5352497
%* peer-reviewed
%Z Chambers, P.; Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ ULB - OPERA
%A Quitin, François
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Polarimetric measurements for spatial wideband MIMO channels
%K ICTEAM:COMM
%G Anglais
%B Proceedings 69th IEEE Vehicular Technology Conference Spring
%D 2009
%U Handle: http://hdl.handle.net/2078.1/88437
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Oguz, Onur
%A Zaidi, Abdellatif
%T Power allocation for improved DF relayed OFDM transmission: the individual power constraint case
%X We consider an OFDM (orthogonal frequency division multiplexing) point to point transmission scheme improved by a relay. For each carrier, symbols sent by the source may be retransmitted during a second time slot by the relay, which is assumed to be of the decode-and-forward (DF) type. For each relayed carrier the destination implements maximum ratio combining. Assuming perfect CSI (channel state information) knowledge the paper investigates the power allocation problem in order to maximize the rate offered by the scheme. Compared to, the second time slot is better used. The source is allowed to transmit a new symbol during this second time slot when the relay is inactive. For this improved protocol, the optimization has been conducted for a sum power constraint and reported in. The present paper is devoted to the case of individual power constraints at the source and at the relay. The theoretical analysis is illustrated by numerical results.
%B ICC 2009 - 2009 IEEE International Conference on Communications
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67587
%R 10.1109/ICC.2009.5199347
%R 10.1109/ICC.2009.5199347
%* peer-reviewed
%Z Vandendorpe, L.; Louveaux, J.; Oguz, O.; Zaidi, A.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Oguz, O.
%A Zaidi, A.
%T Rate-optimized power allocation for OFDM transmission with multiple DF relays and individual power constraints
%X We 1 consider an OFDM (orthogonal frequency division multiplexing) point to point transmission scheme improved by means of multiple relays. For each carrier, symbols sent by the source during a first time slot may be retransmitted during a second time slot by the relays, which are assumed to be of the DF (Decode-and-Forward) type. For each relayed carrier the destination implements maximum ratio combining between what is received over the direct link and what is received from the relay(s). Perfect CSI (channel state information) knowledge is assumed. The paper investigates the power allocation problem in order to maximize the rate offered by the scheme. The source is allowed to transmit a new symbol during the second time slot when none of the relays is assisting. The constraints of decodability at the relays are properly handled. The optimization is conducted for individual constraints on the powers at the source and at the relays. The theoretical analysis is illustrated by numerical results. © EURASIP, 2009.
%K Decode-and-forward
%K Time slots
%K Orthogonal frequency division multiplexing
%K Signal processing
%K Transmissions
%K Optimization
%K Direct links
%K Maximum ratio combining
%K Numerical results
%K OFDM (orthogonal frequency division multiplexing)
%K OFDM transmission
%K Point-to-point transmissions
%K Power allocations
%K Power constraints
%G Anglais
%B Proc. 17th European Signal Processing Conference, EUSIPCO 2009
%D 2009
%U Handle: http://hdl.handle.net/2078.1/137041
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Oguz, Onur
%A Zaidi, Abdellatif
%T Rate-optimized power allocation for OFDM transmission with multiple DF/regenerative relays and an improved protocol
%X We consider an OFDM (orthogonal frequency division multiplexing) point to point transmission scheme improved by means of multiple relays. For each carrier, symbols sent by the source during a first time slot, may be retransmitted during a second time slot by the relays, which are assumed to be of the decode-and-forward (DF) type. For each relayed carrier the destination implements maximum ratio combining. Assuming perfect CSI (channel state information) knowledge the paper investigates the power allocation problem in order to maximize the rate offered by the scheme. Similarly to the protocol proposed in, the source is allowed to transmit a new symbol during the second time slot when none of the relay is assisting. The constraints of decodability at the relays are properly handled. The optimization is conducted for a constraint on the sum of powers at the source and at the relays. Next to the optimized solution, a suboptimum method based on relay selection is proposed and discussed. The theoretical analysis is illustrated by numerical results.
%B 2009 IEEE Wireless Communications and Networking Conference
%I IEEE
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67623
%R 10.1109/WCNC.2009.4917930
%R 10.1109/WCNC.2009.4917930
%* peer-reviewed
%Z Vandendorpe, L.; Louveaux, J.; Oguz, O.; Zaidi, A.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vanhoenacker-Janvier, Danielle
%A Oestges, Claude
%A Montenegro Villacieros, Belén
%A Van Malderen, Roeland
%A De Backer, Hugo
%T Scintillation prediction using improved pre-processed radiosounding data
%X This paper is presenting a model for the prediction of cumulative statistics of amplitude scintillation at microwave frequencies, on an earth-space communication link. This model is using one year of pre-processed radiosonde data for which correction algorithms are applied in order to improve the vertical humidity profiles. The statistics of the vertical profile of the structure constant C/sup 2//sub n/ of the troposphere is then calculated and used for the evaluation of the mean value of the variance of the scintillation amplitude ( sigma /sup 2//sub chi / ). Assuming a Gaussian distribution, the cumulative distribution of sigma /sup 2//sub chi / is then calculated. The statistics have been evaluated for 1990, using radiosonde launches from Uccle, Belgium, and compared to statistics of scintillation variance measured the same year at Louvain-la-Neuve, using the Olympus beacons.
%B Proceedings 3rd European Conference on Antennas and Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67608
%* peer-reviewed
%Z Vanhoenacker-Janvier, D.; Oestges, C.; Montenegro-Villacieros, B.; Microwave Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Quitin, François
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Small-scale variations of cross-polar discrimination in polarized MIMO systems
%K ICTEAM:COMM
%G Anglais
%B Proceedings 3rd European Conference on Antennas and Propagation
%D 2009
%U Handle: http://hdl.handle.net/2078.1/105556
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Czink, Nicolai
%A Bandemer, Bernd
%A Vazquez-Vilar, Gonzalo
%A Jalloul, Louay
%A Oestges, Claude
%A Paulraj, Arogyaswami
%T Spatial separation of multi-user MIMO channels
%X Since multi-antenna (MIMO) systems are becoming more popular thanks to their inherent potential for capacity improvement, interference from MIMO transceivers is an increasingly serious concern. Spatial multiplexing schemes are particularly vulnerable to multi-user interference. Fortunately, this interference can be mitigated, when the channel matrices show a sufficient spatial separation. In this paper, we quantify the separability of multi-user MIMO channels using actual measurements in a scenario where a single outdoor base station transmits to two indoor mobile receivers. To quantify the spatial distance between the two users, we compare the spatial correlation matrices using two simple measures: (i) matrix collinearity, and (ii) the condition number ratio. Both measures are directly linked to MIMO system performance. Our measurement-based evaluations demonstrate that the downlink channels of different users can have a significantly different spatial structure, even when the users are in the same room. This leads to the following conclusions: (i) new multi-user MIMO models are needed to describe the spatial characteristics of different users, and (ii) spatial interference can be well managed by appropriate scheduling and precoding algorithms.
%B Proceedings 20th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2009
%U Handle: http://hdl.handle.net/2078.1/67432
%R 10.1109/PIMRC.2009.5450309
%* peer-reviewed
%Z Czink, N.; Bandemer, B.; Vazquez-Vilar, G.; Paulraj, A.; Smart Antennas Res. Group, Stanford Univ., Stanford, CA, USA Jalloul, L.; Beceem Inc., Santa Clara, CA, USA Oestges, C.; Microwave Lab., Univ. catholique de Louvain (UCL), Louvain-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%T A comprehensive model of dual-polarized channels: from experimental observations to an analytical formulation
%X In this communication, we investigate how to comprehensively model dual-polarized channels. We start with a theoretical description of the relevant mechanisms and parameters describing dual-polarized propagation. We then provide an overview o the most recent experimental results related to dual-polarized channels. It is namely observed that even the first-order statistics of the uplink channel matrix might not be equal to those of the downlink channel. In particular, the XPD might be different on the up- and downlinks and depend on the considered transmitted polarization. Finally, we propose an innovative and realistic model of dual-polarized channels accounting for these observations. The main advantage of the model is its simple analytical formulation, implying that it can easily be used as an abstract formalism to design adequate space-time coding or precoding techniques.
%B Proceedings 3rd International Conference on Communications and Networking in China, CHINACOM
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67703
%R 10.1109/CHINACOM.2008.4685211
%* peer-reviewed
%Z Oestges, C.; Microwave Lab. - Fonds de la Rech. Sci. (FRS-FNRS), Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Bhagavatula, Ramya
%A Oestges, Claude
%A Heath , Robert W.
%+ University of Texas at Austin - ECE
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%T A new MIMO channel model including diversity, orientation and depolarization effects
%D 2008
%K ICTEAM:COMM
%G Anglais
%B USNC-URSI National Radio Science Meeting
%C Boulder, CO, USA
%8 du 04/01/2008 au 04/01/2008
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078.1/105670
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ University of Tewas at Austin - ECE
%+ University of Texas at Austin - ECE
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Bhagavatula, Ramya
%A Heath, Robert W.
%A Oestges, Claude
%T A new MIMO channel representation including spatial diversity, array orientation and depolarization effects
%G Anglais
%B Proceedings IEEE Antennas and Propagation Society International Symposium
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105601
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ ULB - OPERA
%A Quitin, François
%A Horlin, François
%A Oestges, Claude
%A De Doncker, Philippe
%T A new precoding scheme for compact cross-polarized multi-antenna systems
%K ICTEAM:COMM
%G Anglais
%B Proceedings 29th Symposium on Information Theory in the Benelux
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105667
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Roy, Stéphane
%A Oestges, Claude
%T A spatially-correlated tapped delay line model for body area networks
%K ICTEAM:COMM
%G Anglais
%B Proceedings 68th IEEE Vehicular Technology Conference Fall
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105558
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Chaudhary, Muhammad Hafeez
%A Vandendorpe, Luc
%A Zaidi, Abdellatif
%T Adaptive Joint Quantization and Power Allocation in Wireless Sensor Networks
%G Anglais
%B Signals, Systems and Computers, 2008 42nd Asilomar Conference on
%D 2008
%U Handle: http://hdl.handle.net/2078.1/78749
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Quitin, François
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Analytical model and experimental validation of cross polar ratio in polarized MIMO channels
%G Anglais
%B Proceedings 19th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105560
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Quitin, François
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Channel correlation and cross-polar ratio in multi-polarized MIMO channels: analytical derivation and experimental validation
%K ICTEAM:COMM
%G Anglais
%B Proceedings 68th IEEE Vehicular Technology Conference Fall
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105557
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Herzet, C.
%A Vandendorpe, Luc
%T Code-aided ML ambiguity resolution
%X This paper deals with code-aided (CA) maximum-likelihood (ML) phase and timing ambiguity resolution. We propose a methodology based on the sum-product algorithm (SPA) to exactly solve this problem with a tractable complexity. In particular, we emphasize that the proposed ML ambiguity-resolution algorithm has a complexity which is at most equal to the complexity of recently-proposed powerful ML-like ambiguity-resolution methods. Finally, we compare through simulation results the ability of CA and conventional data-aided methods to resolve phase ambiguities.
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67794
%* peer-reviewed
%Z Herzet, C.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Brah, Félix
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T Constrained resource allocation in OFDMA downlink systems with partial CSIT
%X Adaptive resource allocation algorithms based on perfect channel state information at the transmitter (CSIT) improve the performance of OFDMA systems. However, perfect CSIT is rarely possible due to channel estimation errors and channel feedback delay. In this paper, we consider practical subchannel assignment and power allocation strategies for downlink multiuser OFDMA systems, where the base station has imperfect CSI. The goal is to maximize the expected weighted sum rate while satisfying users' minimum data rate and system fairness requirements under total power constraint. We use the Lagrange dual decomposition framework to derive an algorithm that efficiently finds the optimal allocation. Simulation results show the impact of the channel estimation error on the performance of the system and illustrate the trade-off between maximized expected weighted sum rate and the constraints.
%B 2008 International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67766
%* peer-reviewed
%Z Brah, F.; Vandendorpe, L.; Louveaux, J.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Zaidi, Abdellatif
%A Kotagiri, S.
%A Laneman, J.N.
%A Vandendorpe, Luc
%T Cooperative relaying with state available at the relay
%X We consider a state-dependent full-duplex relay channel with the state of the channel non-causally available at only the relay. In the framework of cooperative wireless networks, some specific terminals can be equipped with cognition capabilities, i.e, the relay in our model. In the discrete memoryless (DM) case, we derive lower and upper bounds on channel capacity. The lower bound is obtained by a coding scheme at the relay that consists in a combination of codeword splitting, Gel psila fand-Pinsker binning, and a decode-and-forward scheme. The upper bound is better than that obtained by assuming the availability of state at the source, the relay, and the destination. For the Gaussian case, we also derive lower and upper bounds on channel capacity. The lower bound, obtained by a coding scheme based on combination of codeword splitting and generalized dirty paper coding, is tight in some cases if the channel is physically degraded. The upper bound is also better than that obtained by assuming that the channel state is available at the source, the relay, and the destination.
%B 2008 IEEE Information Theory Workshop (ITW)
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67751
%R 10.1109/ITW.2008.4578638
%R 10.1109/ITW.2008.4578638
%* peer-reviewed
%Z Zaidi, A.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Renterghem, D.
%A Jaspar, Xavier
%A Macq, Benoît
%A Vandendorpe, Luc
%T Distributed source coding with optimized irregular turbo codes
%X We address the problem of distributed source coding of binary sources with side information at the decoder. We propose a compression scheme using irregular turbo codes. We optimize them by maximizing the distance between the two curves of their EXIT charts for given statistics and a compression rate close to the Slepian-Wolf limit in order to increase the robustness of the scheme. This optimized irregular code enables us to achieve compression rates superior to the ones achieved by previously proposed turbo schemes without increasing the decoding complexity.
%K ICTEAM:SIGN
%G Anglais
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67796
%* peer-reviewed
%Z Van Renterghem, D.; Jaspar, X.; Macq, B.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Louveaux, Jérôme
%A Duran, R.T.
%A Vandendorpe, Luc
%T Efficient algorithm for optimal power allocation in OFDM transmission with relaying
%X In this paper we consider an OFDM (orthogonal frequency division multiplexing) transmission scheme with a relay, working in decode-and-forward (DF) mode. Assuming perfect CSI (channel state information) the paper investigates the power allocation problem for rate maximization of the scheme with individual power constraints at the source and at the relay. The theoretical analysis provides a deep understanding of the structure of the solution. Based on this, an efficient iterative algorithm is proposed that exhibits a quicker convergence than classical methods. In addition, it enables to solve the convergence issues observed in some situations.
%B ICASSP 2008. IEEE International Conference on Acoustic, Speech and Signal Processes
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67773
%* peer-reviewed
%Z Louveaux, J.; Duran, R.T.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Kalakech, Ali
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Enhancement of the iterative spectrum balancing algorithm for power allocation in DSL systems
%X The optimization of power allocation in DSL systems is a well studied non-convex problem. In recent years many algorithms have been proposed to solve this problem, but due to the non-convexity, researchers had to rely on heuristic, or exhaustive search algorithms. Iterative spectrum balancing (ISB) is one of these algorithms, that relies on iterative exhaustive search over individual power to achieve the optimization. In this paper we propose to take advantage of an approximate gradient model to reduce the complexity of ISB. Furthermore techniques such as the additional starting point (ASP) and successive optimization are used to bring the result closer to the global optimum.
%B 2008 IEEE Global Telecommunications Conference
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67698
%R 10.1109/GLOCOM.2008.ECP.678
%R 10.1109/GLOCOM.2008.ECP.678
%* peer-reviewed
%Z Kalakech, A.; Louveaux, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Ecole Polytech. de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d’électricité
%A Oestges, Claude
%T Impact of dispersive propagation characteristics on the performance of multi-antenna indoor personal communication systems
%K ICTEAM:COMM
%G Anglais
%B Proceedings XXVIIIth General Assembly of International Union of Radio Science
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105534
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%T Impact of tropospheric depolarization on the performance of dual-polarized high-altitude platform systems
%X The goal of this paper is to investigate the impact of rain and ice depolarization on an hypothetical high altitude platform system operating in the 47-GHz band over central Belgium, and using dual-polarized antenna arrays. An electromagnetic model based on physical parameters (rain rate, ice concentration, rain and ice anisotropy and canting angles) is first described. Time series of physical parameters are then extracted from one year of data recorded during the Olympus experiment in Belgium at 20 GHz. The prediction of attenuation and depolarization based on these parameters is then validated at 12 GHz. Finally, the prediction model is applied to HAPS scenarios by a dual frequency and elevation scaling. The specificity of HAPS is accounted for by considering a range-dependent elevation angle. Performance simulations are eventually presented and illustrate that depolarization may slightly improve the performance of polarization multiplexing schemes.
%B 67th IEEE Vehicular Technology Conference Spring
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67768
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Oguz, Onur
%A Zaidi, Abdellatif
%T Improved OFDM transmission with DF relaying and power allocation for a sum power constraint
%X In this paper we consider an OFDM (orthogonal frequency division multiplexing) transmission scheme with a relay. Symbols sent by the source may or may not be retransmitted during a second time slot by the relay, which is assumed to be of the decode-and-forward (DF) type. For each relayed carrier the destination implements maximum ratio combining. Assuming perfect CSI (channel state information) knowledge the paper investigates the power allocation problem in order to maximize the rate offered by the scheme. Compared to [VDLZ08], the second time slot is better used. The source is allowed to transmit a new symbol during this second time slot when the relay is inactive. The optimization is performed for a sum power constraint. The theoretical analysis is illustrated by numerical results.
%B 3rd International Symposium on Wireless Pervasive Computing (ISWPC 2008)
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67756
%R 10.1109/ISWPC.2008.4556293
%R 10.1109/ISWPC.2008.4556293
%* peer-reviewed
%Z Vandendorpe, L.; Louveaux, J.; Oguz, O.; Zaidi, A.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%T Indoor wireless communications with multiple antennas and polarizations: from channel characterization to performance simulation
%X In this paper, we describe experimental results characterizing the frequency/space/polarization selectivity of indoor channels at 1.9 GHz. Regarding the delay-angle dispersion, a clustered geometry-based model is developed from measurement results and validated. Regarding dual-polarized channels, a simple analytical model is extracted from experimental data, accounting for the cross-correlation between the various parameters. Finally, narrowband dual-polarized and single-polarized transmissions are compared in real-world indoor channels based on performance metrics for multiplexing and diversity gains.
%B 19th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67699
%R 10.1109/PIMRC.2008.4699907
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%A Duhamel, P.
%T Lower bounds on the capacity regions of the relay channel and the cooperative relay-broadcast channel with non-causal side information.
%X In this work, coding for the relay channel (RC) and the cooperative relay broadcast channel (RBC) controlled by random parameters are studied. In the first channel, the RC, information is transferred from the transmitter to the receiver through a multiplicity of nodes which all "simply" act as relays. In the second channel, the cooperative RBC, each intermediate node also acts as a receiver, i.e., it decodes a "private message". For each of these two channels, we consider the situation when side information (SI) S/sup n/ on the random parameters is non- causally provided to the transmitter and all the intermediate nodes but not the final receiver, and derive an achievable rate region based on the relays using the decode-and-forward scheme. In the special case when the channels are degraded Gaussian and the side information (SI) is additive i.i.d. Gaussian, we show that 1) the rate regions are tight and provide the corresponding capacity regions and 2) the state S/sup n/ does not affect these capacity regions, even though the final receiver has no knowledge of the state. For the degraded Gaussian RC, the results in this paper can be seen as an extension of those by Kim et al. to the case of more than one relay.
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67791
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Chalise, B.K.
%A Vandendorpe, Luc
%T MIMO relaying for multiaccess communication in cellular networks
%X We study an amplify and forward (AF) relaying scheme that uses a multiple-input-multiple-output (MIMO) relay to improve the performance of multi-point to point communication in cellular networks. With the assumption that perfect channel state information (CSI) is known, the MIMO relay and the base station (BS) receiver are jointly optimized. The objective is to minimize the sum mean-square error (MSE) while keeping the total transmit power of the relay constant. This problem is solved suboptimally using iterative as well as non-iterative methods. Computer simulations show the performance improvements of the proposed methods over conventional all-pass MIMO relay.
%B 2008 IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM)
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67744
%R 10.1109/SAM.2008.4606843
%R 10.1109/SAM.2008.4606843
%* peer-reviewed
%Z Chalise, B.K.; Vandendorpe, L.; Place du Levant, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Montenegro Villacieros, Belén
%A Vanhoenacker-Janvier, Danielle
%T Multi-dispersive channel characterization for radio localization-based rescue search
%X This paper describes the results achieved by various experimental campaigns aimed at characterizing the directional propagation channel in DCS/UMTS band (1.9 GHz) in indoor and forest areas for similar antenna heights at both ends. These experimental results are useful in the context of pedestrian radio-localization systems relying on cell phone signals. Wideband data, are used to model the channel through various parameters: pathloss, shadowing, fading statistics, delay and azimuth-spreads. For indoor scenarios, path-loss exponents range from 1.4 to 2.2, while the shadowing, temporal K-factor, delay- and azimuth-spreads are found to be lognormally distributed. The RMS delay-spread ranges from 9 ns to 95 ns, whereas the azimuth-spread ranges from 20 to 140 degrees. In forests, the delay-spread, ranging from 60 to 120 ns, is strongly anti-correlated with the temporal coherence, and increases with transmit-to-receive distance. The azimuth-spread remains limited, with average values around 15 degrees.
%B 3rd International Conference on Communications and Networking in China, CHINACOM
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67704
%R 10.1109/CHINACOM.2008.4685026
%* peer-reviewed
%Z Oestges, C.; Montenegro-Villacieros, B.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Giannetti, F.
%A Lottici, V.
%A D'Andrea, N.A.
%T Optimum goodput-oriented power allocation policy for BIC-OFDM packet transmissions
%X In this contribution we study the optimal power allocation scheme for a coded multicarrier transmission. Specifically, we focus on a bit interleaved coded modulation (BICM) packet transmission implemented with Orthogonal Frequency Division Multiplexing (OFDM) and in the presence of automatic repeat request (ARQ) protocol. Based on a simple lower-bound of the rate of information bits received without any error, the so called goodput, we develop a power allocation strategy among the different subcarriers so that the system goodput performance metric is maximized. We also demonstrate the optimality of the solution for the proposed objective function under the given power constraint. The effectiveness of the power allocation policy is numerically testified for BIC-OFDM transmission in the context of typical indoor environment. © 2008 IEEE.
%K Beamforming
%K Wireless telecommunication systems
%K Automatic Repeat requests
%K Bit-interleaved coded modulations
%K Coded multicarrier
%K Goodput performances
%K Indoor environments
%K Information bits
%K Objective functions
%K OFDM transmissions
%K Optimal power allocations
%K Error correction
%K Optimality
%K Packet transmissions
%K Power allocation strategies
%K Power allocations
%K Power constraints
%K Orthogonal frequency division multiplexing
%K Frequency allocation
%K Frequency division multiplexing
%K Modulation
%K Packet networks
%K Semiconductor quantum dots
%K Spectrum analysis
%K Transmissions
%G Anglais
%B Proc. IEEE 10th International Symposium on Spread Spectrum Techniques and Applications (ISSSTA2008)
%D 2008
%U Handle: http://hdl.handle.net/2078.1/137029
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vandendorpe, Luc
%A Duran, R.T.
%A Louveaux, Jérôme
%A Zaidi, Abdellatif
%T Power allocation for OFDM transmission with DF relaying
%X We consider OFDM (orthogonal frequency division multiplexing) transmission helped by a relay. Symbols sent by the source may or may not be retransmitted by a relay during a second time slot. The relay is supposed to operate in Decode-and-Forward (DF) mode. For each carrier the destination implements maximum ratio combining. Assuming perfect CSI (channel state information) knowledge the paper investigates the power allocation problem for rate maximization of the scheme. Both cases of a sum power constraint, and of individual power constraints at the source and at the relay are tackled. The theoretical analysis is illustrated by numerical results for both types of constraints.
%B 2008 International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67746
%* peer-reviewed
%Z Vandendorpe, L.; Duran, R.T.; Louveaux, J.; Zaidi, A.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%A Giannetti, F.
%A Lottici, V.
%A D'Andrea, N.A.
%T Power allocation for goodput optimization in BICM-OFDM systems
%X This paper deals with the power allocation problem for coded multicarrier transmission. Specifically, we focus on a bit interleaved coded modulation (BICM) packet transmission implemented with Orthogonal Frequency Division Multiplexing (OFDM) and in the presence of automatic repeat request (ARQ) protocol. Capitalizing on the binary-input output-symmetric (BIOS) nature of the BICM channel it is provided a simple upper-bound of the rate of information bits received without any error, the so called goodput. Based on this theoretical characterization, we develop a power allocation strategy among the different subcarriers so that the system goodput performance metric is maximized. The effectiveness of the proposed method is numerically testified for BICM-OFDM transmission in the context of the typical WLAN scenario. ©2008 IEEE.
%K Beamforming
%K Wireless telecommunication systems
%K Good put
%K International conferences
%K Power allocation
%K Frequency division multiplexing
%K Computer networks
%K Error correction
%K Frequency allocation
%K Local area networks
%K Modulation
%K Pulse code modulation
%K Telecommunication systems
%K Wireless local area networks (WLAN)
%G Anglais
%B Proc. IEEE International Conference on Communications (ICC 2008)
%D 2008
%U Handle: http://hdl.handle.net/2078.1/137026
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Stupia, Ivan
%A Giannettij, F.
%A Lottici, V.
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T Power and bit allocation for goodput optimization in BIC-OFDM systems
%X This paper contributes with an adaptive modulation scheme intended for bit interleaved coded (BIC) orthogonal frequency division multiplexing (OFDM) packet transmission in the presence of automatic repeat request (ARQ) protocol. The basic idea consists in properly combining the power allocation strategy with a bit-loading procedure among the different subcarriers so that the rate of information bits received without any error is maximized. Numerical simulations corroborate the effectiveness of the proposed scheme when operating over typical wireless environments.1 © 2008 IEEE.
%K Adaptive modulation scheme
%K Packet transmissions
%K Power allocation strategies
%K Sub-carriers
%K Wireless environment
%K Computer simulation
%K Frequency allocation
%K Orthogonal frequency division multiplexing
%K Radio communication
%K Telecommunication services
%K Telecommunication systems
%K Automatic repeat request protocols
%K Wireless networks
%K Bit error rate
%K Basic idea
%K Bit allocation
%K Bit-loading
%K Good put
%K Information bit
%K Numerical simulation
%K OFDM systems
%G Anglais
%B Proc. IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2008)
%D 2008
%U Handle: http://hdl.handle.net/2078.1/137028
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Sneessens, H.H.
%A Jaspar, Xavier
%A Herzet, C.
%A Vandendorpe, Luc
%T Predictions on turbo-decoding performance for adaptive channel coding
%X In this paper we address the calculation of performance characteristics of turbo-codes. The aim is to provide a method that has a low complexity and that enables the analysis of a wide variety of turbo-coded schemes, with in mind the possibility of using it as an optimization criterion in an adaptive system. The proposed method enables the determination of the error-free decoding threshold and of the number of iterations to achieve error-free decoding. Its complexity is far lower than that of existing methods and it offers an accuracy close to that of EXIT charts.
%B 2007 41st Asilomar Conference on Signals, Systems and Computers (ACSSC '07)
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67779
%* peer-reviewed
%Z Sneessens, H.H.; Jaspar, X.; Herzet, C.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Roy, Stéphane
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Propagation modeling for UWB body area networks: power decay and multi-sensor correlations
%K ICTEAM:COMM
%G Anglais
%B Proceedings 10th International Symposium on Spread Spectrum Techniques and Applications
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105652
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Ramon, Valery
%A Herzet, C.
%A Wautelet, X.
%A Vandendorpe, Luc
%T Soft estimation of time-varying frequency selective channels using Kalman smoothing
%X This paper addresses soft estimation of time-varying frequency selective channels using Kalman smoothing. The proposed estimator uses soft extrinsic information provided by a channel decoder. It is intended to improve the performance of an already existing Kalman filtering-based estimator by exploiting all - rather than part of - the data at the receiver disposal. It is the linear estimator exhibiting for the case of interest the minimum mean-squared estimation error. Its complexity is shown to be quite low. An approximated analytical calculation of the mean- squared estimation error (MSEE), both for Kalman filtering and Kalman smoothing, is also proposed. Simulation results illustrate the performance gain of smoothing over filtering and validate our calculation of the MSEE.
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67793
%* peer-reviewed
%Z Ramon, V.; Herzet, C.; Wautelet, X.; Vandendorpe, L.; Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ FTW
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Czink, Nicolai
%A Oestges, Claude
%T The COST 273 MIMO channel model: three kinds of clusters
%K ICTEAM:COMM
%G Anglais
%B Proceedings10th International Symposium on Spread Spectrum Techniques and Applications
%D 2008
%U Handle: http://hdl.handle.net/2078.1/105648
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Sneessens, H.H.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Turbo-coded decode-and-forward strategy resilient to relay errors
%X Cooperation in wireless systems can achieve spatial diversity gains as well as coverage enhancement. In the usual decode-and-forward (DF) strategy, a relay cooperates only when it can decode successfully the signal received from the source. This paper presents instead a DF strategy in which the receiver manages to take advantage of forwarded signals containing errors too. This increases the level of cooperation and is shown to offer significant gains in bit error rate.
%B ICASSP 2008. IEEE International Conference on Acoustic, Speech and Signal Processes
%I IEEE
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67774
%* peer-reviewed
%Z Sneessens, H.H.; Louveaux, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Renaudin, Olivier
%A Kolmonen, Veli-Matti
%A Vainikainen, Pertti
%A Oestges, Claude
%T Wideband MIMO car-to-car radio channel measurements at 5.3 GHz
%X Measurements of car-to-car (C2C) radio channels with 60 MHz bandwidth at 5.3 GHz have been performed in Helsinki, Finland. We focused on 30x30 multiple-input multiple- output (MIMO) measurements, conducted in four environments (urban, sub-urban, campus and highway), under quasi-realistic traffic conditions. As first results, we present in this paper the delay spread statistics for each investigated environment. The largest values of root-mean-square (RMS) delay spread, roughly 2 mu s, were obtained in the urban environment. The narrowband channel fading statistics have also been derived using composite distributions, in order to assess the global fading statistics.
%B Proceedings 68th IEEE Vehicular Technology Conference (VTC 2008-Fall)
%D 2008
%U Handle: http://hdl.handle.net/2078.1/67724
%R 10.1109/VETECF.2008.65
%* peer-reviewed
%Z Renaudin, O.; Kolmonen, V.-M.; Vainikainen, P.; Oestges, C.; Microwave Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Giannetti, F.
%A Lottici, V.
%A Stupia, Ivan
%A Vandendorpe, Luc
%T A low-complexity spreading-code allocation strategy for reduced-PAPR MC-CDMA transmissions
%X In this contribution we demonstrate that the peak-to-average power ratio (PAPR) of a Multi-Carrier Code Division Multiple Access (MC-CDMA) signal can be suitably minimized by resorting to a judicious strategy for the allocation of the spreading signature codes. A low-complexity implementation of the proposed strategy is presented and its performance gain over conventional random allocation strategy is numerically assessed.
%K Chlorine compounds
%K Mobile and wireless communications
%K Multi-Carrier code division multiple access
%K Peak-to-average-power ratio
%K Performance gains
%K Random allocation
%K Codes (standards)
%K Code division multiple access
%K Codes (symbols)
%K Multicarrier modulation
%K Telecommunication
%K Turbo codes
%K Code allocation
%K Low-complexity
%K MC-CDMA
%G Anglais
%B Mobile and Wireless Communications Summit, 2007. 16th IST
%D 2007
%U Handle: http://hdl.handle.net/2078.1/138702
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Duplicy, Jonathan
%A Palomar, D.P.
%A Vandendorpe, Luc
%T Adaptive orthogonal beamforming for the MIMO broadcast channel
%X This paper addresses both the user selection and the linear precoding design of a MIMO broadcast channel where the number of users is assumed to be greater than the number of transmit antennas. The optimization criterion considered is the sum-rate. A greedy algorithm tackling jointly the two issues is developed. It sequentially adds new users so as their beamformers build up an orthonormal basis which is optimized with the help of the channel knowledge assumed to be exhaustive. This solution benefits asymptotically (in the limit of a large number of users) from the full multiplexing and multiuser diversity gains alike the capacity achieving dirty paper coding. Moreover, it exhibits better results than existing schemes and offers some advantages resulting from the choice of an orthogonal structure.
%B 2007 2nd IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67776
%* peer-reviewed
%Z Duplicy, J.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%+ IMEC
%A Roqueta Crusats, Gemma
%A Fort, Andrew
%A Craeye, Christophe
%A Oestges, Claude
%T Analytical propagation models for body area networks
%K ICTEAM:COMM
%G Anglais
%B Proceedings 1st IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications
%D 2007
%U Handle: http://hdl.handle.net/2078.1/105673
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Kalakech, Ali
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Applying the balanced capacity concept to DSL systems
%X This paper investigates a fair resource allocation method in crosstalk limited DSL (digital subscriber line) systems. As a measure of fairness, the concept of balanced capacity (BC), introduced in T. Sartenaer et al. (2005), is used. BC corresponds to a point on the boundary of the capacity region where each user experiences the same relative loss with respect to his maximum capacity. This is especially useful in near-far situations where some users can experience a huge capacity loss if the allocation is performed according to the sum-rate criterion (or any similar criterion). Our goal is to propose efficient algorithms to compute the BC point in DSL systems for constraints on individual power spectrum densities. Results are reported for typical crosstalk limited cases and are compared to a resource allocation optimized for the sum rate. The proposed algorithm is shown to be of low complexity.
%G Anglais
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67795
%* peer-reviewed
%Z Kalakech, A.; Louveaux, J.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Sneessens, H.H.
%A Jaspar, Xavier
%A Herzet, C.
%A Vandendorpe, Luc
%T Calculating turbo-decoding performance characteristics for adaptive channel coding
%X Low complexity performance characterizations of error-correcting codes are needed to better exploit their potential when adapting a communication system to channel conditions or to service requirements. For the case of turbo-codes, existing performance characterizations are often too complex or not flexible enough to be used for real-time adaptation. This paper presents a new technique for evaluating the performance of turbo-codes, that may fit the need for flexibility and low-complexity. It enables the determination of the error-free decoding threshold and of the number of iterations to achieve error-free decoding. Its complexity is far lower than that of existing methods and its accuracy is very satisfying.
%B 2007 IEEE 8th Workshop on Signal Processing Advances in Wireless Communications
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67803
%* peer-reviewed
%Z Sneessens, H.H.; Jaspar, X.; Herzet, C.; Vandendorpe, L.; Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Oǧuz, O.
%A Zaidi, A.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Distributed space-time-frequency block codes for multiple-access-channel with relaying
%X In this paper, we investigate diversity gain in coding for a 2-user multiple-access-channel (MAC) with cooperating transmitters-the MAC with relaying. We propose a simple distributed space-time-frequency block coding (D-STFBC) scheme and analyze the offered diversity gain. In particular, we show that full diversity (order 3) is possible if collaboration is well enough and rigorous signal processing is assumed both at the transmitters and the receiver. Bit-error-rate (BER) analysis and curves are provided for illustrative purposes. © 2007 IEEE.
%K Bit error rate
%K Communication channels (information theory)
%K Signal receivers
%K Transmitters
%K Distributed space-time-frequency block coding (D-STFBC)
%K Diversity gain
%K Codes (symbols)
%G Anglais
%B Proc. 50th Annual IEEE Global Telecommunications Conference (GLOBECOM 2007)
%D 2007
%U Handle: http://hdl.handle.net/2078.1/137025
%R 10.1109/GLOCOM.2007.333
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Duran, R.T.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Goodput optimized bit and power allocation for OFDM transmission with relaying
%X This paper considers point to point transmission over frequency selective channels by means of OFDM (orthogonal frequency division multiplexing), and enhanced by means of a decode-and-forward (DAF) relay. Assuming that perfect channel state information is available at the transmission side, this paper intends to solve the problems of power and bit allocation for goodput maximization. A greedy approach is proposed where the number of bits to be allocated is increased one at a time till a maximum value of the goodput is reached. The performance of the algorithm is illustrated with simulations, and compared with uniform power allocation and waterfilling approaches.
%B 2007 IEEE International Symposium on Signal Processing and Information Technology
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67799
%* peer-reviewed
%Z Duran, R.T.; Louveaux; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Chalise, B.K.
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T MIMO relaying for multi-point to multi-point communication in wireless networks
%X In this paper, we propose a relaying scheme that uses a fixed multiple-input-multiple-output (MIMO) relay to improve the performance of the multi-point to multi-point communication in wireless networks. Under the assumption that the perfect channel state information (CSI) is known, we propose the MIMO relay which minimizes its total transmit power by satisfying the signal-to-interference-and-noise-ratio (SINR) requirement for all destinations. This paper shows that the aforementioned problem is non-convex but it can be relaxed to a convex problem using the semidefinite relaxation technique. Computer simulations show that the proposed MIMO relay outperforms the conventional all-pass MIMO relay.
%B 2007 2nd IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67777
%* peer-reviewed
%Z Chalise, B.K.; Vandendorpe, L.; Louveaux, J.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Guillaud, Maxime
%A Debbah, Merouane
%T Multi-polarized MIMO communications: channel model, mutual information and array optimization
%X This paper considers the use of n/sub r/ * n/sub t/ dual-polarized arrays for improving the mutual information of MIMO communications. We first develop an elegant model of the multi-polarized MIMO channel, which allows to account for spatial correlation and depolarization effects. The major advantage of the model lies in its analytical expression, whose parameters have a clear physical meaning. In a second part, we investigate the ergodic mutual information of multi-polarized schemes, and derive a condition upon which multi-polarized transmissions offer a higher capacity than equivalent uni-polarized schemes using the same number of antennas under the same overall array dimensions.
%B Proceedings 8th IEEE Wireless Communications and Networking Conference
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67875
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Clerckx, Bruno
%T Mutual information and error probability of dual-polarized systems
%X In this communication, we address the potential benefits of dual-polarized arrays in 2 * 2 MIMO systems. We start with a new and simple analytical model of dual-polarized Rayleigh and Ricean fading channels, which relies on a limited number of physical parameters, such as the spatial correlations, the co-polar gain imbalance and the cross-polar discrimination. Then, we investigate the multiplexing advantage of dual-polarized transmissions through the evaluation of the ergodic mutual information. Finally, the performance of two space-time coding schemes (Alamouti O-STBC and uncoded spatial multiplexing) is evaluated via a detailed analysis of the pairwise error probability.
%B Proceedings 8th IEEE Wireless Communications and Networking Conference
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67874
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Brah, F.
%A Vandendorpe, Luc
%A Louveaux, Jérôme
%T OFDMA constrained resource allocation with imperfect channel knowledge
%X Adaptive resource allocation has been shown to provide substantial performance gain in OFDMA based wireless systems when perfect channel state information (CSI) is available at the transmitter. However, perfect CSI at the transmitter (CSIT) is rarely possible due to channel estimation errors and channel feedback delay. In this paper, we consider practical resource allocation strategies for downlink multiuser OFDMA systems, where the base station has imperfect CSI. We address the problem of subchannel assignment and power allocation, to maximize the ergodic sum utility under QoS, fairness and total power constraints. This constrained optimization problem is formulated as a non-convex finite dimensional stochastic problem. We use Lagrange dual decomposition framework to derive an algorithm that efficiently finds the optimal allocation. Simulation results show the impact of the channel estimation error on the performance of the system and illustrate the trade-off between maximized utility and the constraints. ©2007 IEEE.
%K Adaptive systems
%K Resource allocation
%K Technology
%K Transmitters
%K Wireless telecommunication systems
%K Adaptive resource allocations
%K Base stations
%K Channel feedbacks
%K Channel-estimation errors
%K Constrained optimization problems
%K Downlink multiuser
%K Channel state information
%K Ergodic
%K Finite dimensional
%K Imperfect channel knowledge
%K Lagrange dual
%K Ofdma systems
%K Optimal allocation
%K Perfect channel state information
%K Performance gains
%K Power allocation
%K Resource allocation strategies
%K Constrained optimization
%K Simulation results
%K Sub-channel assignment
%K Total power
%K Vehicular technologies
%K Wireless systems
%K Channel estimation
%K Constraint theory
%K Estimation
%K Frequency division multiple access
%K Information retrieval
%K Management
%K Planning
%G Anglais
%B Proc. 14th IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT 2007)
%D 2007
%U Handle: http://hdl.handle.net/2078.1/137024
%* peer-reviewed
%0 Conference Paper
%9 Présentation orale avec comité de sélection
%A Oestges, Claude
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%T Overview of channel and radio propagation models for wireless dual-polarized systems
%D 2007
%K ICTEAM:COMM
%G Anglais
%B URSI North American Radio Science Meeting
%C Ottawa, ON, Canada
%8 du 22/07/2007 au 26/07/2007
%* peer-reviewed
%U Handle: http://hdl.handle.net/2078.1/105621
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vandendorpe, Luc
%A Duran, R.T.
%A Louveaux, Jérôme
%A Zaidi, Abdellatif
%T Power allocation for OFDM transmission with DF relaying
%X In this paper we consider an OFDM (orthogonal frequency division multiplexing) transmission scheme with a relay. Symbols sent by the source may or may not be retransmitted during a second time slot by the relay, which is assumed to be of the decode-and-forward (DF) type. For each carrier the destination implements maximum ratio combining. Assuming perfect CSI (channel state information) knowledge the paper investigates the power allocation problem for rate maximization of the scheme. Both cases of a sum power constraint, and of individual power constraints at the source and at the relay are tackled. The theoretical analysis is illustrated by numerical results for both types of constraints.
%B 14th IEEE Annual Symposium on Communications & Vehicular Technology(SCVT)
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67830
%* peer-reviewed
%Z Vandendorpe, L.; Duran, R.T.; Louveaux, J.; Zaidi, A.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Rate regions for the partially-cooperative relay broadcast channel with non-causal side information
%X In this work, we consider a partially cooperative relay broadcast channel (PC-RBC) controlled by random parameters. We provide rate regions for two different situations: (1) when side information (SI) S/sup n/ on the random parameters is non-causally known at both the source and the relay and, (2) when side information S/sup n/ is non-causally known at the source only. These achievable regions are derived for the general discrete memoryless case first and then extended to the case when the channel is degraded Gaussian and the SI is additive i.i.d. Gaussian. In this case, the source uses generalized dirty paper coding (GDPC), i.e., DPC combined with partial state cancellation, when only the source is informed, and DPC alone when both the source and the relay are informed. It appears that, even though it can not completely eliminate the effect of the SI (in contrast to the case of source and relay being informed), GDPC is particularly useful when only the source is informed.
%B 2007 IEEE International Symposium on Information Theory
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67778
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Devillers, Bertrand
%A Armada, A.G.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Resource allocation for goodput optimization in parallel subchannels with error correction and selective repeat ARQ
%X This paper deals with the problem of allocating bits and power among a set of parallel frequency-flat subchannels. The objective is to maximize the number of information bits delivered without error to the user by unit of time, or good-put. We consider a frame-oriented transmission with convolutional coding, hard Viterbi decoding, and selective repeat automatic repeat request (ARQ) retransmission protocol. An expression for the goodput of the considered communication system is derived. Different bit and power allocations strategies are proposed and compared to one another using simulations. It turns out that the best trade-off between performance and complexity is achieved by allocating the power in such a way that the bit error rate is equal on all subchannels, and by allocating the bits by rounding the solution to the problem obtained by relaxing the constraint of integer constellation sizes. © 2007 EURASIP.
%K Automatic repeat request
%K Viterbi decoding
%K Communication systems
%K Error correction
%K Signal processing
%K Viterbi algorithm
%K Data communication systems
%K Bit and power allocation
%K Constellation sizes
%K Convolutional coding
%K Good put
%K Information bit
%K Retransmissions
%K Selective Repeat
%K Subchannels
%G Anglais
%B Proc. 15th European Signal Processing Conference (EUSIPCO 2007)
%D 2007
%U Handle: http://hdl.handle.net/2078.1/137019
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Duplicy, Jonathan
%A Vandendorpe, Luc
%T Robust MMSE precoding for the MIMO complex Gaussian broadcast channel
%X This paper addresses the design of the linear precoders and decoders of the complex Gaussian broadcast channel in which both the base station and the remote station are equipped with arrays of multiple antennas. An imperfect channel knowledge is assumed at the base station and the minimization of the sum of the mean square errors (MMSE) of the system's substreams is chosen as optimization criterion. A stochastic approach is taken to make the design robust against the channel estimation errors. The solution is based on an iterative algorithm whose convergence is guaranteed. Simulations results emphasize the benefit of the proposed design.
%B 2007 IEEE International Conference on Acoustics, Speech, and SignalProcessing (IEEE Cat. No. 07CH37846)
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67883
%* peer-reviewed
%Z Duplicy, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Zaidi, Abdellatif
%A Vandendorpe, Luc
%T Sensitivity of achievable rates for the relay channel. Application to relaying with channel estimation error
%X This paper investigates the sensitivity of the achievables rates for the full-duplex relay channel to small additive disturbances on channel links. The focus is on two relaying strategies - the decode-and-forward (DF) mode and the compress-and-forward (CF) mode. We use Fisher Information and De-Bruijn's identity to assess the decrease in the corresponding rates due to small additive contaminating noise. Analysis sheds light on the respective sensitivity levels of these schemes and hence, provides insights onto the choice of appropriate relaying strategies in the situations where some trade-off between transmission rate and sensitivity is needed. Next, we show that these results can be used to emphasize the effect of channel estimation error on relaying transmissions. An important (somehow intuitive) observation at this stage is that transmission through the direct link (i.e., relay is off) may improve upon both decode-and-forward and compress-and-forward schemes, when the channel is "bad enough". Finally, a lower bound on the capacity of a relay channel under channel estimation error is obtained by combining well known relaying strategies, each over the appropriate SNR range. Analysis is supported by some examples.
%B 2007 IEEE International Conference on Acoustics, Speech, and SignalProcessing (IEEE Cat. No. 07CH37846)
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67884
%* peer-reviewed
%Z Zaidi, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Vanhoenacker-Janvier, Danielle
%T Time series-based prediction of fade dynamics and shadowing correlation statistics for navigation systems
%X In this paper, a physical-statistical approach is used in combination with time series simulations, which rely directly upon distributions of physical parameters and simple electromagnetic theory to predict fade dynamics and shadowing correlation statistics for navigation systems. In the former case, a UTD-based ray-tracing is used with a series of roadside buildings, randomly generated according to known statistical distributions for building height and spacing, street width, etc. When dealing with shadowing correlation statistics for a given satellite constellation, the distribution of the shadowing correlation coefficient is then obtained by deriving time series of first and second elevation angles as well as of azimuth separation, using an orbit generator as input.
%B Proceedings 2nd European Conference on Antennas and Propagation
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67719
%* peer-reviewed
%Z Oestges, C.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Mallat, Achraf
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T UWB based positioning in multipath channels: CRBs for AOA and for hybrid TOA-AOA based methods
%X In this paper we consider UWB (ultra wide band) based positioning. We derive the CRBs (Cramer Rao bound) for AOA (angle of arrival) and for hybrid method using both AOA and TOA (time of arrival) information. Both non modulated and modulated IR-UWB (impulse-radio) waveforms are considered. The UWB channel is supposed to be of the multipath type. The AOA technique is investigated without NB (narrow band) approximation usually made. The analytical results obtained for the CRBs are illustrated by numerical results for typical scenarios.
%G Anglais
%B 2007 IEEE International Conference on Communications
%I IEEE
%D 2007
%U Handle: http://hdl.handle.net/2078.1/67792
%* peer-reviewed
%Z Mallat, A.; Louveaux, J.; Vandendorpe, L.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Roy, Stéphane
%A Oestges, Claude
%A Horlin, François
%A De Doncker, Philippe
%T Ultra-wideband spatial channel characterization for body area networks
%K ICTEAM:COMM
%G Anglais
%B Proceedings 2nd European Conference on Antennas and Propagation
%D 2007
%U Handle: http://hdl.handle.net/2078.1/105671
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Van Roy, Stéphane
%A Oestges, Claude
%T Ultra-wideband spatial correlation study for multi-sensor multi-antenna body area networks
%K ICTEAM:COMM
%G Anglais
%B Proceedings 1st IET Seminar on Antennas and Propagation for Body-Centric Wireless Communications
%D 2007
%U Handle: http://hdl.handle.net/2078.1/105680
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Kalakech, A.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T A balanced capacity implementation of DSM for DSL systems
%X This paper investigates a fair resource allocation method in crosstalk limited DSL systems. As a measure of fairness, the concept of Balanced Capacity (BC), introduced in [1], is used. BC corresponds to a point of the boundary of the capacity region where each user experiences the same relative loss with respect to his maximum capacity. Our goal is to propose algorithms to compute the corresponding point in DSL (Digital Subscriber Line) systems where some users suffer from a near-far situation and for constraints on individual power spectrum densities. Results are reported for typical crosstalk limited cases and are compared to a resource allocation optimized for the sum rate. © 2006 IEEE.
%K Communication
%K Telecommunication lines
%K Telephone lines
%K Capacity regions
%K Digital Subscriber Line (xDSL)
%K DSL systems
%K Fair resource allocation
%K Individual (PSS 544-7)
%K Maximum capacity
%K Near-far
%K Power spectrum density (PSD)
%K Crosstalk
%K Sum rate
%K Vehicular technologies
%K DSL
%K Management
%K Modems
%K Planning
%K Power spectrum
%K Resource allocation
%K Technology
%K Telecommunication equipment
%G Anglais
%B Proc. 13th Annual Symposium on Communications and Vehicular Technology in the Benelux (SCVT 2006)
%D 2006
%U Handle: http://hdl.handle.net/2078.1/137010
%R 10.1109/SCVT.2006.334369
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Devillers, Bertrand
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Exploiting cyclic prefix for performance improvement in single carrier systems
%X Cyclic prefixed single carrier (CP-SC) transmission over frequency selective channels is considered. In conventional CP-SC systems, the cyclic prefix is discarded at the receiver side. This suboptimal strategy allows simple frequency domain equalization. In this paper, a new CP-SC receiver exploiting the whole received signal (including the cyclic prefix) for data estimation is proposed. With reasonable additional complexity, the proposed architecture outperforms the conventional CP-SC receiver, in terms of bit error rate. Simulations results show that the proposed scheme also improves the goodput, i.e. error-free rate, of the communication link.
%K Bit error rate
%K Wireless telecommunication systems
%K Bit errors
%K Communication link
%K Cyclic prefix (CO)
%K Cyclic-prefixed single-carrier (CPSC)
%K Data estimation
%K Frequency selective (FS) channels
%K Frequency-domain equalization (FDE)
%K Goodput
%K Performance improvements
%K Carrier communication
%K SC systems
%K Single-carrier (SC) systems
%K Suboptimal strategies
%K Wireless (WiFi) communication
%K Signal receivers
%K Civil aviation
%K Communication channels (information theory)
%K Error analysis
%K Mobile telecommunication systems
%K Signal processing
%K Telecommunication
%K Terminology
%G Anglais
%B Proc. IEEE 7th Workshop on Signal Processing Advances in Wireless Communications (SPAWC 2006)
%D 2006
%U Handle: http://hdl.handle.net/2078.1/137018
%R 10.1109/SPAWC.2006.346409
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Clerckx, Bruno
%A Bollen, Laurent
%A Vanhoenacker-Janvier, Danielle
%T Indoor channel characterization of diversity-based nomadic wireless systems
%X This paper aims at characterizing the wireless channel for nomadic diversity-based systems operating at 1.9 GHz. Using a 1 * 2 wideband measurement chain, four indoor environments have been investigated: a corridor, a small office, an electrical engineering laboratory, and an industrial hall. The measurement equipment is constituted by an 80-MHz transmitter. At the receiver, two omnidirectional antennas are connected to a wideband channel sounder through a switch, in order to measure an estimate of the instantaneous vector channel. Special attention is given to the experimental procedure itself, so as to take into account the specificity of nomadic systems (as opposed to usual mobile systems). The measurement analysis reveals that the shadowing, Ricean K-factor and delay-spread are lognormally distributed. A path-loss model is derived, and cross-correlations between K-factor, delay-spread and shadowing are analyzed. The channel correlations at the user terminal or at the access point are also derived, and related to the individual channel characteristics.
%B Proceedings Global Telecommunications Conference, GLOBECOM
%D 2006
%U Handle: http://hdl.handle.net/2078.1/67928
%* peer-reviewed
%Z Oestges, C.; Clerckx, B.; Bollen, L.; Vanhoenacker-Janvier, D.; Lab. of Microwave, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Brah, F.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Optimal resource allocation for MIMO OFDM-CDM systems under power, QoS and fairness constraints
%X In this paper we consider resource allocation for throughput maximization and QoS/fairness support in the downlink of a multiuser multi-antennas OFDM-CDM systems with transmit zero-forcing beamforming. The impact of the relaxation of the QoS/fairness constraints on the system throughput is analyzed. The resource allocation problem, with relaxable constraints, formulated as a nonlinear nonconvex optimization problem is efficiently and globally solved through geometric programming in his convex form. Simulation results are provided for different values of the relaxation parameters and illustrate the achievable trade-off between system throughput and QoS/fairness requirements. © 2006 IEEE.
%K Antenna accessories
%K Resource allocation
%K Technology
%K Throughput
%K Downlink (DL)
%K Fairness constraints
%K Geometric programming (GP)
%K MIMO-OFDM
%K Multi users
%K Multi-antennas
%K Non convex optimization problem
%K Continuum damage mechanics
%K OFDM-CDM
%K Optimal resource allocation
%K Relaxation parameters
%K Resource allocation problems
%K Simulation results
%K System throughput
%K Throughput maximization
%K Vehicular technologies
%K Zero forcing beamforming (ZFBF)
%K Communication
%K Frequency allocation
%K Frequency division multiplexing
%K Management
%K MIM devices
%K Optimization
%K Orthogonal frequency division multiplexing
%K Planning
%G Anglais
%B Proc. 13th Annual Symposium on Communications and Vehicular Technology in the Benelux (SCVT 2006)
%D 2006
%U Handle: http://hdl.handle.net/2078.1/137014
%R 10.1109/SCVT.2006.334368
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Vanhoenacker-Janvier, Danielle
%A Oestges, Claude
%A Martellucci, Antonio
%T Prediction of scintillation cumulative statistics using classical and high resolution radiosoundings
%X Scintillation has an important impact on the Earth-space propagation and affects the fade mitigation techniques developed for frequencies above 20 GHz. Scintillation being a random variation superimposed on the signal, it is described by its variance. Most of the exiting models predict the cumulative distribution function (cdf) of scintillation from ground measured parameters, such as temperature and humidity. The use of radiosoundings increases the accuracy of the prediction. Some problems have however to be solved, such as the sensitivity of the cdf to the value of some derivatives used in the calculation. High resolution radiosoundings give better height accuracy but increase the noise present in the calculation. Preliminary solutions are proposed to improve the processing of the radiosonde data and the results are compared with measured data.
%B Proceedings 1st European Conferencie on Antennas and Propagation
%D 2006
%U Handle: http://hdl.handle.net/2078.1/67879
%* peer-reviewed
%Z Vanhoenacker-Janvier, D.; Oestges, C.; Microwave Lab., UCL, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Brah, Félix
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Proportional fair power allocation for OFDM-CDM systems in frequency-selective Rayleigh fading channels
%X Orthogonal frequency division multiplexing with code division multiplexing (OFDM-CDM) is one of the combined schemes of OFDM and CDMA techniques. The CDM component enables additional diversity in frequency selective fading channels. This paper proposes an optimal power allocation via proposal-fair strategy for the OFDM-CDM-based systems. A zero-forcing beamformer is used at the mobile unit and the basestation optimizes its power allocation to maximize the sum-rate subject to fairness constraints. Two optimization techniques are proposed. Simulation results are provided for typical downlink situation and a fairness index is compared to that of system optimized without fairness request.
%B 2006 IEEE 7th Workshop on Signal Processing Advances in WirelessCommunications (IEEE Cat No. 06EX1431)
%I IEEE
%D 2006
%U Handle: http://hdl.handle.net/2078.1/67885
%* peer-reviewed
%Z Brah, F.; Louveaux, J.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Mallat, Achraf
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T UWB based positioning: Cramer Rao bound for angle of arrival and comparison with time of arrival
%X In this paper we consider the potential of UWB (ultra wide band) signals for positioning. We consider both TOA (time of arrival) and AOA (angle of arrival) based methods. For the AOA method we use a linear array of equi-spaced elements. We derive the CRB associated with this method, without using the monochromatic assumption. The CRBs of both methods are compared. The analytical results are illustrated for UWB signals having the spectral occupation fulfilling the FCC emission mask. We show that, for far field conditions and practical numbers of antenna array elements, TOA outperforms AOA. However the accuracy provided by AOA is shown to be very interesting. © 2006 IEEE.
%K Antenna accessories
%K Time of Arrival (TOA)
%K Ultra- WideBand (UWB)
%K UWB signaling
%K Vehicular technologies
%K Communication
%K Antenna arrays
%K Technology
%K Analytical results
%K Angle of Arrival (AOA)
%K Antenna array elements
%K Cramer-Rao Bound (CRB)
%K Far-field conditions
%K Linear arrays
%G Anglais
%B Proc. 13th Annual Symposium on Communications and Vehicular Technology in the Benelux (SCVT 2006)
%D 2006
%U Handle: http://hdl.handle.net/2078.1/137016
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Duplicy, J.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Utility-based MIMO uplink beamforming
%X This paper1 addresses the design of transmit and receive beamformers in a Multiple-Input Multiple-Output (MIMO) uplink system. To optimize the beamformers, we introduce a new utility function denned as a weighted difference between users' rates and their transmit power. This new criterion allows to take into account whether the users are more rate-sensitive or powersensitive. Beamformers and power allocation are iteratively computed by resorting to the framework of non-cooperative game theory. ©2006 IEEE.
%K Game theory
%K Beamforming
%K Iterative methods
%K Optimization
%K Power control
%K Signal receivers
%K Transmitters
%K Multiple Input Multiple Output (MIMO) uplink systems
%K Power allocation
%K Utility functions
%G Anglais
%B Proc. 4th IEEE Sensor Array and Multichannel Signal Processing Workshop Proceedings (SAM 2006)
%D 2006
%U Handle: http://hdl.handle.net/2078.1/137015
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Oestges, Claude
%T Validity of the Kronecker model for MIMO correlated channels
%X The goal of this paper is to investigate the validity of the Kronecker model for MIMO correlated channels. First, mathematical and equivalent propagation conditions of validity are detailed. In a second part, we address several areas where the Kronecker model is not valid. We also review the one-ring model and experimental results dealing with the validation of the Kronecker model. Based on these scarce results, the preliminary conclusion is that the Kronecker model might not be valid for arrays larger than 2*2 when antenna correlations are high across both receive and transmit arrays. The paradox is that the Kronecker model has been developed and is being widely used to account for correlation. This is in strong contrast with the popular belief that the Kronecker model is valid in many indoor and outdoor cases.
%B Proceedings 63rd IEEE Vehicular Technology Conference Spring
%D 2006
%U Handle: http://hdl.handle.net/2078.1/67920
%* peer-reviewed
%Z Oestges, C.; Fonds Nat. de la Recherche Sci., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Wautelet, X.
%A Herzet, C.
%A Vandendorpe, Luc
%T Cramer Rao bounds for channel estimation with symbol a priori information
%X In this paper we derive the Cramer-Rao bound (CRB) for the estimation of a multiple-input multiple-output (MIMO) channel when a given a priori information about the transmitted sequence is available. This approach also enables to compute the non-data-aided (NDA) bound, i.e. the CRB when the receiver only knows the symbol constellation. We explore various scenarios, including the case of a deterministic channel and the case of a random channel. Numerical evaluations of the CRB-based bounds are presented for different channels. In particular, the influence of the symbol-constellation size is highlighted. Finally, the performance of an estimator based on the expectation-maximization algorithm is shown to be very close to the proposed bounds.
%B The Sixth IEEE International Workshop on Signal Processing Advances inWireless Communications (IEEE Cat. No. 05EX992)
%I IEEE
%D 2005
%U Handle: http://hdl.handle.net/2078.1/67951
%* peer-reviewed
%Z Wautelet, X.; Herzet, C.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Jaspar, Xavier
%A Vandendorpe, Luc
%T Design and performance analysis of joint source-channel turbo schemes with variable length codes
%X We proposed in Jaspar et al. (2004) a joint source-channel (JSC) turbo-(de)coder combining a variable length code (VLC) with a turbo-code. The simulation results showed the better performance and the lower decoding complexity of this new scheme over the previous ones. In this paper, we provide tools for the analysis and the performance prediction of this scheme. The bit, symbol and frame distance spectra are developed for VLC and for the more general case of VLC turbo-concatenated with an error correcting code (ECC). These spectra are then used to get the union bounds on the bit, symbol and frame error probabilities, and to shed some light on previous simulation-based results. These tools are also valid for a wide variety of other similar schemes currently explored in the literature and, hence, can be used to analyze and to compare them.
%B 2005 IEEE International Conference on Communications (IEEE Cat. No.05CH37648)
%I IEEE
%D 2005
%U Handle: http://hdl.handle.net/2078.1/67954
%* peer-reviewed
%Z Jaspar, X.; Vandendorpe, L.; Commun. & Remote Sensing Lab, Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Louveaux, Jérôme
%A Van Der Veen, A.-J.
%T Downstream vdsl channel tracking using limited feedback for crosstalk precompensated schemes
%X With increasing bandwidths and decreasing loop lengths, crosstalk becomes the main impairment in VDSL systems. For downstream communication, crosstalk precompensation techniques have been designed to cope with this issue by using the collocation of the transmitters. These techniques naturally need an accurate estimation of the crosstalk channel impulse responses. We investigate the issue of tracking these channels. Due to the lack of coordination between the receivers, and because the amplitude levels of the remaining crosstalk channels after precompensation are very low, blind estimation schemes are inefficient in this case. So some part of the upstream or downstream bit rate needs to be used to help the estimation. In this paper, we design a new algorithm to try to limit the bandwidth used for the estimation purpose by exploiting the collocation at the transmitter side. The principle is to use feedback from the receiver to the transmitter instead of using pilots in the downstream signal. It is shown by simulations that the proposed estimation is more efficient, in terms of needed overhead, than a classical scheme using pilot symbols. ©2005 IEEE.
%K Algorithms
%K Computational complexity
%K Computer simulation
%K Crosstalk
%K Transmitters
%K Channel tracking
%K Crosstalk precompensated schemes
%K Crosstalk precompensation
%K Video signal processing
%G Anglais
%B Proc. IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP'05)
%D 2005
%U Handle: http://hdl.handle.net/2078.1/137005
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Duplicy, J.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Interference-free multi-user MIMO-OFDM
%X A multi-user downlink MIMO-OFDM scheme is considered. Perfect channel knowledge is assumed at the base station and linear processing is used at both the transmit and receive sides. The objective is to optimize the mean BER of the system while satisfying a transmit power constraint and fulfilling each user's rate. FDMA and SDMA are investigated. We show how the multi-user interference induced by SDMA can be annihilated and exhibit that this multiple access technique should be preferred to FDMA. © 2005 IEEE.
%K Bit error rate
%K Communication channels (information theory)
%K Signal interference
%K Telecommunication systems
%K Transmitters
%K Multi-user interference
%K Multiple access technique
%K Power constraint
%K Orthogonal frequency division multiplexing
%G Anglais
%B Proc. IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP'05)
%D 2005
%U Handle: http://hdl.handle.net/2078.1/137003
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Vanhoenacker-Janvier, Danielle
%A Clerckx, Bruno
%T Macrocellular directional channel modeling at 1.9 GHz: cluster parametrization and validation
%X This paper describes the extraction of cluster parameters at the user terminal from wideband data measured at 1.9 GHz in short-range outdoor macrocellular environments. Clusters are first identified through data visual inspection. Then, a statistical characterization is carried out based on delay-oriented classification of the clusters. Results show that, at each location, six to eight clusters are present, with average cluster delay and azimuth spreads of about 10 to 15 nanoseconds and 10 to 20 degrees respectively. The model is validated with measurement results, including correlations for broadside and inline receive antenna configurations.
%B Proceedings 61st IEEE Vehicular Technology Conference Spring
%D 2005
%U Handle: http://hdl.handle.net/2078.1/67950
%* peer-reviewed
%Z Oestges, C.; Vanhoenacker-Janvier, D.; Clerckx, B.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Duplicy, J.
%A Louveaux, Jérôme
%A Vandendorpe, Luc
%T Optimization of linear pre/decoders for multi-user closed-loop MIMO-OFDM
%X This paper deals with a multi-user downlink MIMO-OFDM scheme with perfect channel knowledge at both the transmit and receive sides. The objective is to optimize the average BER while fulfilling each user's rate and satisfying a global transmit power constraint. Space Division Multiple Access (SDMA) is investigated and three new iterative schemes are proposed to compute the linear pre/decoders. The results exhibit, inter alia, that orthogonalizing the channels does not lead to the best results. © 2005 IEEE.
%K Downlink
%K Space division multiple access
%K Decoders
%K Multiple input multiple output (MIMO)
%K Power constraint
%K Orthogonal frequency division multiplexing
%K MIMO
%K Multi-user
%K OFDM
%K SDMA
%K Channel capacity
%K Decoding
%K Iterative methods
%K Optimization
%G Anglais
%B Proc. IEEE International Conference on Communications (ICC'05)
%D 2005
%U Handle: http://hdl.handle.net/2078.1/136994
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Jaspar, Xavier
%A Vandendorpe, Luc
%T Performance and convergence analysis of joint source-channel turbo schemes with variable length codes
%X Recently, we proposed a joint source-channel (JSC) turbo (de)coder combining a variable length code (VLC) and a turbo code, and applied it to image transfer (Jaspar, X. and Vandendorpe, L., SCC Conf., p.279-86, 2004; ICC Conf., p.2606-10, 2004). Simulation results showed that this scheme gave better performance and lower decoding complexity than previous ones. The paper assesses the performance of such a scheme at all signal-to-noise ratios on the channel. Analytical tools are provided for the understanding and optimization of a wide variety of similar schemes currently explored in the literature. More precisely, the bit, symbol and frame distance spectra are developed for VLCs and for VLCs turbo-concatenated with an error correcting code (ECC), in order to get bounds on the corresponding error rates. Also EXIT charts are extended to three dimensions in order to analyze the turbo-convergence of the scheme.
%B 2005 IEEE International Conference on Acoustics, Speech, and SignalProcessing (IEEE Cat. No.05CH37625)
%I IEEE
%D 2005
%U Handle: http://hdl.handle.net/2078.1/67962
%* peer-reviewed
%Z Jaspar, X.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Ramon, Valery
%A Vandendorpe, Luc
%T Predicting the performance and convergence behavior of a turbo-equalization scheme
%X This paper proposes a simple and time non-consuming method to predict, at any iteration, the performance of a turbo equalization scheme using a soft-in/soft-out (SISO) minimum mean square error (MMSE)/interference cancellation (IC) equalizer and a SISO decoder. Gaussianity of the extrinsic log-likelihood ratios (LLRs) output by the equalizer as well as the decoder is assumed. This paper shows that the equalizer behavior may then be very reliably predicted only by calculations (no simulations are needed) whereas that of the decoder requires simulations for only one independent input parameter. Comparison between the proposed prediction method and plain simulations of the overall turbo equalization scheme shows that our method accurately determines the system performance at any iteration.
%B 2005 IEEE International Conference on Acoustics, Speech, and SignalProcessing (IEEE Cat. No.05CH37625)
%I IEEE
%D 2005
%U Handle: http://hdl.handle.net/2078.1/67960
%* peer-reviewed
%Z Ramon, V.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Dejonghe, Antoine
%A Vandendorpe, Luc
%T Bounding the error-floor of turbo-equalized BICM transmission over quasi-static frequency-selective Rayleigh fading channels
%X This paper provides bounds on the error-floor of turbo-equalization (TE), considering transmission over quasi-static frequency-selective (FS) Rayleigh fading channels, and assuming bit-interleaved coded modulation (BICM) at the transmitter. The expressions of the corresponding asymptotic coding gain and diversity order are also provided. More generally, this leads to a framework enabling to assess the asymptotic performance of similar BICM-based turbo systems.
%B 2004 IEEE International Conference on Communications (IEEE Cat.No.04CH37577)
%I IEEE
%D 2004
%U Handle: http://hdl.handle.net/2078.1/68007
%* peer-reviewed
%Z Dejonghe, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%T Channel correlations and capacity metrics in MIMO dual-polarized Rayleigh and Ricean channels
%X This communication highlights the impact of channel correlations, including cross-correlation terms, on various relevant metrics, namely the squared channel Frobenius norm and as well as capacity metrics, directly linked with the channel covariance matrix. Using the developed metrics, lie compare various antenna configurations, with a focus on multi-polarized systems. Several orthogonal schemes, such as horizontal-vertical and slant schemes, are investigated, and analytical expressions are presented.
%B Proceedings 60th IEEE Vehicular Technology Conference Fall
%D 2004
%U Handle: http://hdl.handle.net/2078.1/67974
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Louveaux, Jérôme
%A Siclet, C.
%A Pinchon, D
%A Siohan, P.
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%T Comparison of two filterbank optimization criteria for VDSL transmission
%X In this paper, we consider the use of filterbank based multicarrier modulation for VDSL transmission. We compare two filterbank optimization criteria, i.e. the maximization of the time-frequency localization and the minimization of the out-of-band energy and we show that filterbank optimized according to the time-frequency criterion achieve better rates and allow the use of reduced size equalizers.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 3124
%P 142-149
%D 2004
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2004
%U Handle: http://hdl.handle.net/2078.1/61229
%R 10.1007/978-3-540-27824-5_21
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Czyz, J.
%A Sadeghi, M
%A Kittler, J
%A Vandendorpe, Luc
%+ Université catholique de Louvain (UCL) - Autre
%T Decision fusion for face authentication
%X In this paper we study two aspects of decision fusion for enhancing face authentication. First, sequential fusion of scores obtained on successive video frames of a user's face is used to reduce the error rate. Secondly, the opinions of several face authentication algorithms are combined so that the combined decision is more accurate than the best algorithm alone. The experiments performed on a realistic database demonstrate that the fully automatic multi-frame - multi-experts system proposed in this work allows a significant improvement over the static single-expert system.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 3072
%P 686-693
%D 2004
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2004
%U Handle: http://hdl.handle.net/2078.1/61246
%R 10.1007/978-3-540-25948-0_93
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Ramon, Valery
%A Herzet, C.
%A Vandendorpe, Luc
%A Moeneclaey, M.
%T EM algorithm-based multiuser synchronization in turbo receivers
%X The current paper addresses the issue of estimating the user propagation delays, received carrier phase offsets and received amplitudes in an asynchronous DS-CDMA environment with frequency non-selective propagation channels. The proposed synchronizer is based on the expectation-maximization (EM) algorithm and takes benefit from the soft information delivered by the receiver which is of the turbo type. The performance of the proposed synchronizer is illustrated by simulation results. In particular, the mean and the mean squared error of the estimator, as well as the bit error rate reached by the synchronized system, are reported.
%B 2004 IEEE International Conference on Acoustics, Speech, and SignalProcessing
%I IEEE
%D 2004
%U Handle: http://hdl.handle.net/2078.1/68017
%* peer-reviewed
%Z Ramon, V.; Herzet, C.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Messer, K
%A Kittler, J
%A Sadeghi, M
%A Hamouz, M
%A Kostyn, A
%A Marcel, S
%A Bengio, S
%A Cardinaux, F
%A Sanderson, C
%A Poh, N
%A Rodriguez, Y
%A Kryszczuk, K
%A Czyz, J.
%A Vandendorpe, Luc
%A Ng, J
%A Cheung, H
%A Tang, B.
%+ Université catholique de Louvain (UCL) - Autre
%T Face authentication competition on the BANCA database
%X This paper details the results of a face verification competition [2] held in conjunction with the First International Conference on Biometric Authentication. The contest was held on the publically available BANCA database [1] according to a defined protocol [6]. Six different verification algorithms from 4 academic and commercial institutions submitted results. Also, a standard set of face recognition software from the internet [3] was used to provide a baseline performance measure.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 3072
%P 8-15
%D 2004
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2004
%U Handle: http://hdl.handle.net/2078.1/61245
%R 10.1007/978-3-540-25948-0_2
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Clerckx, Bruno
%A Vanhoenacher-Janvier, D.
%A Vandendorpe, Luc
%T Improved space-time trellis codes for correlated MIMO channels
%X Space-time code designs commonly rely on the assumption of independent and identically distributed (i.i.d.) Rayleigh channels. However, poor scattering conditions can have detrimental effects on the performance of space-time codes. We derive new space-time trellis codes that are robust in the presence of a large variety of propagation conditions. First, robust space-time trellis codes are derived when the transmitter has no channel knowledge. Then, trellis codes exploiting some statistical knowledge of the channel at the transmitter are presented. Codes satisfying these criteria are shown to perform much better in real-world channels than codes designed only for i.i.d. channels.
%B 2004 IEEE 60th Vehicular Technology Conference. VTC2004-Fall (IEEE Cat.No.04CH37575)
%I IEEE
%D 2004
%U Handle: http://hdl.handle.net/2078.1/67973
%* peer-reviewed
%Z Clerckx, B.; Vanhoenacher-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Clerckx, Bruno
%A Vanhoenacker-Janvier, Danielle
%A Vandendorpe, Luc
%T Linear dispersion codes for a (not so) large number of receive antennas
%X Linear dispersion codes (LDC) are high-rate codes that exploit both the spectral efficiency and the diversity a multiple-input multiple-output (MIMO) system may offer. However they are complex to design for high spectral efficiency and their designs have been limited to the case of independent and identically Rayleigh distributed (i.i.d.) channels. In this paper we design channel correlation based LDC under the assumption of a large number of receive antennas and show by simulations. that large gains can he obtained from such designed codes. Moreover, deep connections between so designed codes and capacity achieving codes are pointed out.
%B 2004 IEEE 60th Vehicular Technology Conference. VTC2004-Fall (IEEE Cat.No.04CH37575)
%I IEEE
%D 2004
%U Handle: http://hdl.handle.net/2078.1/67975
%* peer-reviewed
%Z Clerckx, B.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Dejonghe, Antoine
%A Vandendorpe, Luc
%T A comparison of bit and symbol interleaving in MMSE turbo-equalization
%X The purpose of this paper is to compare bit and symbol interleaving in turbo-equalization (TE) schemes. Considering a single binary encoder and memoryless mapper, the corresponding transmission schemes are respectively bit-interleaved coded modulation (BICM) and trellis-coded modulation (TCM) over a static frequency selective channel. Appropriate turbo processing at the receiver is ensured in both cases. For the sake of tractability, efficient low-complexity MMSE-based implementations are proposed. The asymptotic performance of the resulting bit- and symbol-interleaved TE schemes is then linked with that of the underlying coded modulation schemes. As an extension to [X. Li, J. Ritcey, 1999], this enables to show that bit-interleaved TE with carefully chosen constellation mapping and proper implementation can outperform its symbol-interleaved counterpart.
%B 2003 IEEE International Conference on Communications (Cat. No.03CH37441)
%I IEEE
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68034
%* peer-reviewed
%Z Dejonghe, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Herzet, C.
%A Ramon, Valery
%A Vandendorpe, Luc
%A Moeneclaey, M.
%T An iterative soft decision directed linear timing estimator
%X The paper addresses the issue of estimating the symbol timing in turbo receivers. We propose a linear timing estimator which benefits from the soft information delivered by the turbo system at each iteration to compute the timing estimate. This estimator is then compared to a synchronizer based on the expectation-maximization (EM) algorithm (Herzet, C. et al., ICASSP, 2003). Performance of the proposed synchronizer is illustrated by simulation results and proves better than that of the EM-based counterpart regarding both convergence speed and range.
%B 2003 4th IEEE Workshop on Signal Processing Advances in WirelessCommunications - SPAWC 2003 (IEEE Cat. No.03EX689)
%I IEEE
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68019
%* peer-reviewed
%Z Herzet, C.; Ramon, V.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Vanhoenacker-Janvier, Danielle
%A Paulraj, Arogyaswami
%T Dual-polarized MIMO macrocellular wireless transmissions: modeling, validation and analysis
%X This paper addresses the extension of a physical scattering model to multi-polarized transmissions. The initial approach is based on a geometrical distribution of obstacles derived from known power-delay profiles. In this paper, each scattering process is described by a matrix reflection coefficient corresponding to dual-polarization states. Ultimately, the model allows one to simulate the effects of the range on capacity, branch power-ratio and cross-polar discrimination. Simulation results are compared with existing measurements at 2.5 GHz. The proposed model is then used to investigate various dual-polarization 2*2 MIMO schemes, such 0 degrees /90 degrees or 45 degrees , as well as to optimize the design of multi-polarized MIMO schemes.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 58th IEEE Vehicular Technology Conference Fall
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68030
%* peer-reviewed
%Z Oestges, C.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Herzet, C.
%A Ramon, Valery
%A Vandendorpe, Luc
%A Moeneclaey, M.
%T EM algorithm-based timing synchronization in turbo receivers
%X The paper addresses the issue of estimating the sampling instant in turbo receivers. The proposed synchronizer is based on the expectation-maximization (EM) algorithm and takes benefit from the soft information delivered by the turbo system. Performance of the proposed synchronizer is illustrated by simulation results. In particular, the mean and the variance of the estimator as well as the bit error rate reached by the synchronized system are reported.
%B 2003 IEEE International Conference on Acoustics, Speech, and SignalProcessing (Cat. No.03CH37404)
%I IEEE
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68050
%* peer-reviewed
%Z Herzet, C.; Ramon, V.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Messer, K
%A Kittler, J
%A Sadeghi, M
%A Marcel, S
%A Marcel, C
%A Bengio, S
%A Cardinaux, F
%A Sanderson, C
%A Czyz, J.
%A Vandendorpe, Luc
%A Srisuk, S
%A Petrou, M
%A Kurutach, W
%A Kadyrov, A
%A Paredes, R
%A Kepenekci, B
%A Tek, FB
%A Akar, GB
%A Deravi, F
%A Mavity, N
%+ Université catholique de Louvain (UCL) - Autre
%T Face verification competition on the XM2VTS database
%X In the year 2000 a competition was organised to collect face verification results on an identical, publicly available data set using a standard evaluation protocol. The database used was the Xm2vts database along with the Lausanne protocol [14]. Four different institutions submitted results on the database which were subsequently published in [13]. Three years later, a second contest using the same dataset and protocol was organised as part of AVBPA 2003. This time round seven seperate institutions submitted results to the competition. This paper presents the results of the competition and shows that verification results on this protocol have increased in performance by a factor of 3.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 2688
%P 964-974
%D 2003
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2003
%U Handle: http://hdl.handle.net/2078.1/61505
%R 10.1007/3-540-44887-X_112
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Clerckx, Bruno
%A Vanhoenacker-Janvier, Danielle
%A Paulraj, Arogyaswami
%T Impact of diagonal correlations on MIMO capacity: application to geometrical scattering models
%X The paper highlights the impact of channel correlations on the capacity of MIMO communications, with a focus on the so called diagonal correlations. Based on this analysis, the limitations of simplified mathematical representations, such as the Kronecker or the diagonal-decorrelation models, are pointed out. Finally, the correlation properties of characteristic geometrical scattering models are studied in order to analyze whether these models can be adequately represented by the simplified formalisms, as well as to quantify the errors introduced by these simplifications. With respect to channel correlations, neither the Kronecker model nor the diagonal-decorrelation assumptions are good representations of the investigated geometrical scattering models. When comparing capacity values, it is found that the diagonal-decorrelation model may yield significant errors. In particular, relative errors on ergodic or outage capacity may be significant for the Kronecker model.
%K ICTEAM:COMM
%G Anglais
%B Proceedings 58th IEEE Vehicular Technology Conference Fall
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68029
%* peer-reviewed
%Z Oestges, C.; Clerckx, B.; Vanhoenacker-Janvier, D.; Microwave Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Zuyderhoff, D.
%A Wautelet, X.
%A Dejonghe, Antoine
%A Vandendorpe, Luc
%T MMSE turbo receiver for space-frequency bit-interleaved coded OFDM
%X This paper considers transmission of OFDM modulated signals over MIMO frequency-selective fading channels. To benefit from diversity, coding is introduced in the space and frequency dimensions by means of bit-interleaved coded modulation. Assuming the OFDM cyclic extension works properly, MIMO space equalization has to be performed for each individual tone. A set of low-complexity MMSE SISO equalizers, achieving both spatial-interference mitigation and demodulation, is used. This set of MMSE equalizers exchanges soft information with the SISO decoder according to the turbo principle. The performance of this scheme is illustrated by computer simulations for quasistatic frequency-selective channels. It is shown that this receiver is able to exploit space and frequency diversity.
%B 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEECat. No.03CH37484)
%I IEEE
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68028
%* peer-reviewed
%Z Zuyderhoff, D.; Wautelet, X.; Dejonghe, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Clerckx, Bruno
%A Vanhoenacker-Janvier, Danielle
%A Oestges, Claude
%A Vandendorpe, Luc
%T Mutual coupling effects on the channel capacity and the space-time processing of MIMO communication systems
%X The channel capacity and the performance of MIMO systems in the presence of fading correlation and antenna coupling are investigated. Simulation results demonstrate that mutual coupling can improve the performance depending on the inter-element spacing and the richness of scattering. It is shown the bit error rate performance of spatial multiplexing is particularly influenced by the decorrelation/correlation effect caused by mutual coupling. On the other hand, the bit error rate performance of transmit diversity is mainly affected by the resulting modification of antenna gain and received power.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Communications
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68035
%* peer-reviewed
%Z Clerckx, B.; Vanhoenacker-Janvier, D.; Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Clerckx, Bruno
%A Vanhoenacker-Janvier, Danielle
%A Oestges, Claude
%A Vandendorpe, Luc
%T Robust signal constellations for spatial multiplexing in the presence of real fading propagation channels
%X Spatial multiplexing is employed in MIMO communication systems to increase spectral efficiency. The performance of spatial multiplexing is highly dependent on the propagation conditions such as the richness of scattering, the presence of dominant components and the inter-element spacings. In this paper, new robust signal constellations for use in spatial multiplexing over real fading propagation channels are developed. It is shown that these new constellations are by far more robust against fading correlations and high Rice factor than the classical PSK and QAM constellations. With these new constellations, spatial multiplexing presents excellent symbol error rate performance whatever the propagation environment and the inter-element distance.
%K ICTEAM:COMM
%G Anglais
%B Proceedings IEEE International Conference on Communications
%D 2003
%U Handle: http://hdl.handle.net/2078.1/68036
%* peer-reviewed
%Z Clerckx, B.; Vanhoenacker-Janvier, D.; Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Czyz, J.
%A Bengio, S
%A Marcel, C
%A Vandendorpe, Luc
%+ Université catholique de Louvain (UCL) - Autre
%T Scalability analysis of audio-visual person identity verification
%X In this work, we present a multimodal identity verification system based on the fusion of the face image and the text independent speech data of a person. The system conciliates the monomodal face and speaker verification algorithms by fusing their respective scores. In order to assess the authentication system at different scales, the performance is evaluated at various sizes of the face and speech user template. The user template size is a key parameter when the storage space is limited like in a smart card. Our experimental results show that the multimodal fusion allows to reduce significantly the user template size while keeping a satisfactory level of performance. Experiments are performed on the newly recorded multimodal database BANCA.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 2688
%P 752-760
%D 2003
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2003
%U Handle: http://hdl.handle.net/2078.1/61504
%R 10.1007/3-540-44887-X_87
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%T A physical-statistical channel model of macro- and megacellular terrestrial networks and its application to polarization multiplexing
%X This communication describes a physically oriented statistical approach that predicts narrowband fading statistics for macro- and megacellular metropolitan networks. The model is successfully compared with experimental data at 1.6 GHz and applied to several simulation schemes including polarization multiplexing.
%B Proceedings 5th International Symposium on Wireless Personal Multimedia Communications. Proceedings (Cat. No.02EX568)
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68071
%R 10.1109/WPMC.2002.1088235
%* peer-reviewed
%Z Oestges, C.; Microwave Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Sartenaer, T.
%A Vandendorpe, Luc
%T About the sensitivity of FB modulations to timing offsets
%X This paper studies the impact of timing errors in the receivers for baseband filter bank (FB) modulation techniques, including DMT and multicode modulations. Matched filtering detectors are first investigated, followed by MMSE linear and DF detectors.
%B 2002 IEEE International Conference on Communications. ConferenceProceedings. ICC 2002 (Cat. No.02CH37333)
%I IEEE
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68109
%R 10.1109/ICC.2002.997097
%* peer-reviewed
%Z Sartenaer, T.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Hubaux, Damien
%A Vandendorpe, Luc
%A Legat, Jean-Didier
%T Adaptation du calcul du CRC à une architecture parallèle à instructions longues
%K ICTEAM:CIRC
%G Français
%B Proceedings of SympA'8
%D 2002
%U Handle: http://hdl.handle.net/2078.1/97859
%* peer-reviewed
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Kittler, J
%A Ballette, M
%A Czyz, J.
%A Roli, F
%A Vandendorpe, Luc
%+ Université catholique de Louvain (UCL) - Autre
%T Decision level fusion of intramodal personal identity verification experts
%X We investigate the Behavior Knowledge Space [4] and Decision Templates [7] methods of classifier fusion in the context of personal identity verification involving six intramodal experts exploiting frontal face biometrics. The results of extensive experiments on the XM2VTS database show the Behavioural Knowledge Space fusion strategy achieves consistently better results than the Decision Templates method. Most importantly, it exhibits quasi monotonic behaviour as the number of experts combined increases.
%G Anglais
%J Lecture Notes in Computer Science
%B Lecture Notes in Computer Science
%V 2364
%P 314-324
%D 2002
%@ 0302-9743 (ISSN)
%@ 1611-3349 (e-ISSN)
%* peer-reviewed
%D 2002
%U Handle: http://hdl.handle.net/2078.1/61633
%R 10.1007/3-540-45428-4_31
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - SST/ICTM/ELEN - Pôle en ingénierie électrique
%A Louveaux, Jérôme
%A Salvekar, A.A.
%A Cioffi, J.
%T Frame synchronization for multiuser digital subscriber line systems
%X Multiuser detection in DSL systems has recently gained some attention. Several methods have been proposed and they provide a significantly increased data rate. However, there are several issues that must be resolved in order to realize the asserted improvements. These issues include the frame synchronization of the different users. We analyze in this paper the issue of frame synchronization in a multiuser DSL environment. We propose a novel method to solve this issue that utilizes DSL specific characteristics to overcome obstacles that make the general problems difficult or intractable. Then, the performances of the proposed scheme are analyzed.
%K Communication channels (information theory)
%K Computer simulation
%K Data reduction
%K Synchronization
%K Digital subscriber lines (DSL)
%K Signal detection
%G Anglais
%B Proc. IEEE Global Telecommunications Conference (Globecom 2002)
%D 2002
%U Handle: http://hdl.handle.net/2078.1/136986
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - MD/RAIM - Département de radiologie et d'imagerie médicale
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Havran, Carmen
%A Hupet, Laurent
%A Czyz, Jacek
%A Lee, John Aldo
%A Vandendorpe, Luc
%A Verleysen, Michel
%T Independent component analysis for face authentication
%X Independent component analysis (ICA) is presented as an alternative feature extraction algorithm to principal component analysis (PCA) widely used in automatic face recognition/authentication tasks. We show that the promising ICA algorithm extracts from faces features that are relevant and efficient for authentication. This leads to improved success rates and a reduced client model size over a PCA based feature extraction.
%K ICTEAM:MLAI
%G Anglais
%B Knowledge-Based Intelligent Information Engineering Systems and Allied Technologies
%E Damiani, E.; Howlett, R.J.; Jain, L.C.; Ichalkaranje, N.
%I IOS press
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68039
%* peer-reviewed
%Z Havran, C.; Hupet, L.; Czyz, J.; Lee, J.; Vandendorpe, L.; Verleysen, M.; Electricity Dept., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Hubaux, Damien
%A Guedria, Lotfi
%A Vandendorpe, Luc
%A Verleysen, Michel
%A Legat, Jean-Didier
%T Nouvelles méthodes de conception de systèmes électroniques intégrés
%K ICTEAM:CIRC
%K ICTEAM:MLAI
%G Français
%B Proceedings of SympA'8
%D 2002
%U Handle: http://hdl.handle.net/2078.1/97862
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Guenach, M.
%A Vandendorpe, Luc
%T Performance analysis of DA and DD multiuser tap weight estimators for short code DS-CDMA systems
%X We investigate the performance of three multiuser tap weight estimators for multipath channels in data aided (DA) and decision directed (DD) modes for a BPSK DS-CDMA reverse link. The tap weights are estimated using different algorithms working separately or jointly in order to obtain good estimates as required for coherent detection or synchronization purposes. The performance of these algorithms and their sensitivity to the observation window, to the delay estimation error and to the difference between successive delays are investigated. A comparison between Hadamard and Gold codes is also included. The mean squared estimation error (MSEE) is computed and compared to the Cramer-Rao lower bound (CRLB).
%B 2002 IEEE International Conference on Communications. ConferenceProceedings. ICC 2002 (Cat. No.02CH37333)
%I IEEE
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68112
%R 10.1109/ICC.2002.996823
%* peer-reviewed
%Z Guenach, M.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Ikonomou, D.
%A Vandendorpe, Luc
%T Performance comparison of receivers for the up-link of cyclic prefixed and non-prefixed MC-CDMA systems
%X Ikonomou (see Ph.D. Dissertation, UCL, Belgium, June 2002) and Ikonomou and Vandendorpe (see European Transactions on Telecommunications (ETT) Journal, vol.10, no.4, p.407-415, July/August 1999) proposed two fractionally spaced (FS) decision feedback equalising (DFE) receivers performing single user detection (SUD) or joint detection (JD) used in non-cyclic prefixed (NCP) multicarrier-CDMA (MC-CDMA) schemes. The objective of this paper is to compare the performance of the above two equalising schemes, against a simpler receiver structure consisting by a single-tap filter bank used in a cyclic prefixed (CP) MC-CDMA scheme. In the context of the latter, two different banks of single-tap filters are presented: one designed to perform classical zero forcing (ZF) detection and one designed for the minimum mean square error (MMSE) criterion. A comparison is finally made in terms of the bit error rate (BER) between NCP MC-CDMA schemes that use equalising receivers and schemes that use the CP extension technique.
%B 13th IEEE International Symposium on Personal Indoor and Mobile RadioCommunications. PIMRC 2002. Proceedings (Cat. No.02TH8637)
%I IEEE
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68065
%R 10.1109/PIMRC.2002.1047338
%* peer-reviewed
%Z Ikonomou, D.; Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Dejonghe, Antoine
%A Vandendorpe, Luc
%T Turbo-equalization for multilevel modulation: an efficient low-complexity scheme
%X This paper addresses the problem of iterative equalization and decoding (turbo-equalization) when bit-interleaved multilevel modulations are considered. The goal is to propose an efficient low-complexity solution in this context, where optimal turbo-equalization is totally untractable. Therefore, we generalize reduced-complexity soft-in/soft-out (SISO) equalizers based on the minimum mean square error (MMSE) criterion (originally proposed in a BPSK context) to this particular scheme. Performances are illustrated through simulations. We show the influence of the mapping on the signal-to-noise ratio (SNR) threshold and on asymptotic performances, and link the obtained results to iterative demodulation and decoding on an additive white Gaussian noise (AWGN) channel.
%B 2002 IEEE International Conference on Communications. ConferenceProceedings. ICC 2002 (Cat. No.02CH37333)
%I IEEE
%D 2002
%U Handle: http://hdl.handle.net/2078.1/68108
%R 10.1109/ICC.2002.997171
%* peer-reviewed
%Z Dejonghe, A.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Horlin, F.
%A Vandendorpe, Luc
%T Channel adapted CDMA for MAI/ISI-free power optimized burst transmission with space diversity at the base station
%X This paper considers the uplink and the downlink of a DS-CDMA multiuser communication system based on burst transmission over frequency selective channels. The purpose is to evaluate the performance gain obtained if space diversity is introduced at the base station with an optimized set of codes. The codes are designed in order to minimize the emitted power at the mobile stations (in case of uplink transmission) or at the base station (in case of downlink transmission) while allowing the complete elimination of the intersymbol interference (ISI) and multiple-access interference (MAI) if filters matched to the total impulse responses are used at the receiver. An iterative algorithm is used to generate the codes. The comparison is made with the performances reached when a conventional set of codes is used. It is shown that the precoding scheme based on channel adapted codes significantly outperforms a system based on a conventional set of codes.
%B GLOBECOM'01. IEEE Global Telecommunications Conference (Cat.No.01CH37270)
%I IEEE
%D 2001
%U Handle: http://hdl.handle.net/2078.1/68124
%R 10.1109/GLOCOM.2001.965686
%* peer-reviewed
%Z Horlin, F.; Vandendorpe, L.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Guenach, M.
%A Vandendorpe, Luc
%T Design and performance analysis of DA multiuser path trackers for long code DS-CDMA systems
%X We investigate timing recovery structures for a DS-CDMA multiuser uplink using codes with a period of several symbols named long codes and operating over frequency selective multipath and slowly Rayleigh fading channels. In order to implement RAKE reception the delays of the different paths have to be estimated and the estimates have to be updated. We extend interference mitigation to this estimation problem and design timing recovery schemes accounting for the intersymbol interference (ISI) and the multiple access interference (MAI) present in the signal. We first propose a multirate description of the long code DS-CDMA uplink. Then based on this formalism we revisit the optimum data-aided (DA) maximum likelihood (ML) delay estimation structure and the suboptimum early-late implementation. The sensitivity of the synchronizers to imperfect knowledge of path gains to the period of the long codes and to near-far situations is also investigated.
%B GLOBECOM'01. IEEE Global Telecommunications Conference (Cat.No.01CH37270)
%I IEEE
%D 2001
%U Handle: http://hdl.handle.net/2078.1/68121
%R 10.1109/GLOCOM.2001.965715
%* peer-reviewed
%Z Guenach, M.; Vandendorpe, L.; Commun. & Remote Sensing Lab., UCL, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Vandendorpe, Luc
%A Horlin, F.
%A Sartenaer, T.
%T FSLE and FSDF joint detectors for long code DS-CDMA
%X We investigate detection structures for a DS-CDMA. multiuser uplink using codes with a period of several symbols, named long codes. We first propose a multirate description of the uplink. Then based on this formalism we revisit a number of popular receiver structures: RAKE receivers, minimum mean square error linear and decision feedback fractionally spaced detectors.
%B 2001 IEEE International Conference on Acoustics, Speech, and SignalProcessing. Proceedings (Cat. No.01CH37221)
%I IEEE
%D 2001
%U Handle: http://hdl.handle.net/2078.1/68157
%R 10.1109/ICASSP.2001.940449
%* peer-reviewed
%Z Vandendorpe, L.; Horlin, F.; Sartenaer, T.; Commun. & Remote Sensing Lab., Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL)
%A Ciblat, P.
%A Vandendorpe, Luc
%T Non-data-aided carrier frequency offset estimation for OFDM and downlink DS-CDMA systems
%X We address the problem of non-data aided frequency offset estimation for non-circular transmissions over frequency-selective channels in a downlink DS-CDMA system or an OFDM communications context. We observe that twice the frequency offset is a cyclic frequency of the received signal. We thus introduce an estimator relying on the maximisation of the empirical cyclocorrelations. We analyse its asymptotic behaviour and obtain a closed-form expression for the asymptotic covariance. This enables us to design relevant system parameters. Simulations are provided and confirm our assertions.
%B IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings(Cat. No.01CH37211)
%I IEEE
%D 2001
%U Handle: http://hdl.handle.net/2078.1/68131
%R 10.1109/VTC.2001.957225
%* peer-reviewed
%Z Ciblat, P.; Vandendorpe, L.; Lab. de Telecommun. et Teledetection, Univ. Catholique de Louvain, Louvain-la-Neuve, Belgium
%0 Journal Article
%9 Présentation orale avec comité de sélection
%A Macq, Benoît
%A Labeau, F.
%A Desset, C
%A Vandendorpe, Luc
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%T Image processing for multimedia terminals and related architectures
%X The multimedia terminals of tomorrow are seen today as toolboxes containing flexible solutions not only able to compress audio-visual flows, but also to interact with the contents, provide tools for copyright protection, adapt the signal representations to the communication channels, etc. The aim of this paper is to overview a flexible architecture suited for dynamically downloadable environments, discuss briefly new functionalities demanded for image communications and present more deeply a system globally optimized for noisy channels. The description of these three items illustrates the needs for image processing research to integrate in a global approach the communication software design, the new functionalities, among which security and copyright protection are of major importance, and to globally optimize the different codings, e.g. source and channel codings. (C) 2000 Elsevier Science B.V. All rights reserved.
%K Image Processing
%K Joint Source-channel Coding
%K Watermarking
%K Dynamic Downloadable Platform
%G Anglais
%J Signal Processing
%B Signal Processing
%! Signal Process.
%V 80
%N 7
%P 1167-1183
%D 2000
%@ 0165-1684 (ISSN)
%@ 1872-7557 (e-ISSN)
%* peer-reviewed
%D 2000
%U Handle: http://hdl.handle.net/2078.1/62145
%R 10.1016/S0165-1684(00)00029-3
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Vanhoenacker-Janvier, Danielle
%T Performance prediction of a 47 GHz stratospheric communication system
%K ICTEAM:COMM
%G Anglais
%B Proceedings Millennium Conference on Antennas and Propagation
%D 2000
%U Handle: http://hdl.handle.net/2078.1/105962
%* peer-reviewed
%0 Book Section
%9 Présentation orale avec comité de sélection
%+ Université catholique de Louvain (UCL) - FSA/ELEC - Département d'électricité
%A Oestges, Claude
%A Maufroid, Xavier
%A Vanhoenacker-Janvier, Danielle
%T Performance simulation of a Ka band multimedia LEO satellite system
%K ICTEAM:COMM
%G Anglais
%B Proceedings 6th Ka Band Utilization Conference
%D 2000
%U Handle: http://hdl.handle.net/2078.1/105961
%* peer-reviewed