Exploring mobile/WiFi handover with multipath TCP

Mobile Operators see an unending growth of data traffic generated by their customers on their mobile data networks. As the operators start to have a hard time carrying all this traffic over 3G or 4G networks, offloading to WiFi is being considered. Multipath TCP (MPTCP) is an evolution of TCP that allows the simultaneous use of multiple interfaces for a single connection while still presenting a standard TCP socket API to the application. The protocol specification of Multipath TCP has foreseen the different building blocks to allow transparent handover from WiFi to 3G back and forth. In this paper we experimentally prove the feasibility of using MPTCP for mobile/WiFi handover in the current Internet. Our experiments run over real WiFi/3G networks and use our Linux kernel implementation of MPTCP that we enhanced to better support handover. We analyze MPTCP's energy consumption and handover performance in various operational modes. We find that MPTCP enables smooth handovers offering reasonable performance even for very demanding applications such as VoIP. Finally, our experiments showed that lost MPTCP control signals can adversely affect handover performance; we implement and test a simple but effective solution to this issue.