Multipath TCP with real Smartphone applications

Multipath TCP is a new TCP extension that allows spreading data across several paths. Smartphone are multi-homed devices that can take advantage of such ability. Compared to regular TCP, Multipath TCP is able to keep connections alive across different networks. This work explores three measurement campaigns. The first one analyses how Multipath TCP reacts on smartphones relative to TCP with predefined scenarios on real applications and partial control of the environment. We propose and implement an automated measurement framework and observe that Multipath TCP works on smartphones without requiring any change on the application. With the default scheduler, quite long connections are balanced on both interfaces depending of their performance, but behaviour of short connections mainly depends on the initial interface. The second one extends our analysis to real users and compare the traffic with the one seen by a Multipath TCP server. We show the heterogeneity of the subflows and observe that most of the subflows created by smartphones are not used. Multipath TCP's reinjections are quite rare, but can happen in burst, particularly in mobility scenarios. The third one studies the performance of Multipath TCP with the streaming use case. We notice that Multipath TCP offers a better service than TCP to its handover mechanisms. However, the current behaviour of Multipath TCP is not always what smartphone users expect and we propose several possible improvements for the current implementation.