Analog/digital hybrid precoding for SWIPT systems

The purpose of this research is to understand the trade-off between the communication rate and the energy harvested in a multiple-input and multiple-output simultaneous wireless information and power transfer system. This will help the conception of accurate simultaneous communications for many users and the supply of batteryless devices. In this work, the rate and the energy harvested will be maximized, ensuring a certain level of harvested energy such that batteryless devices can be activated. Some simulations have been launched with an isotropic normalized Rayleigh channel on three different, previously built, models of optimization namely signal coordination, multi-service coordination of a fully digital system and multi-service coordination of a hybrid precoding with an antenna array system. The outcomes are that the rate as well as the energy harvested are increasing with the input power of the system for the three models, and that the multi-service coordination of a hybrid precoding system achieves the best performance in terms of rate (14.4 bit/s/Hz for an array of two antennas and 16.3 bit/s/Hz for an array of 4 antennas) and energy harvested (234 mJ for two antennas per array and 441 mJ for 4 antennas per array) in comparison with signal coordination (14.3 bit/s/Hz and 42.7 mJ) and multi-service coordination of a fully digital system (12.4 bit/s/Hz and 116 mJ) at an input power of 20 dBm and any threshold of activation of the harvester devices (from 1 mJ to 2.5 mJ). This comparison shows that the multi-service coordination of a hybrid precoding system is advantageous, compared to 3G or 4G systems, in terms of communication accuracy and harvested energy for femtocell base stations in a static environment.