Multi-path transport over heterogeneous wireless networks: Does it really pay off?

Multi-path transfer protocols such as Concurrent Multi-Path Transfer for SCTP and Multi-Path TCP (MPTCP), are becoming increasingly popular, due to widespread deployment of smartphones with multi-homing support. Although the idea of using multiple interfaces simultaneously to improve application throughput is tempting, does transmission over multiple interfaces always provide benefits especially in realistic setup? In this paper, we first show that multi-path transfer might actually have a negative impact in real-world scenarios with mobile broadband and wireless LAN networks. We then introduce our Dynamic Relative Path Scoring (DRePaS) algorithm that continuously evaluates the contribution of paths to the overall performance and dynamically influences the scheduling decisions to make best use of the paths for the overall system performance. We show that DRePaS outperforms the current MPTCP implementation in terms of throughput and application delay, especially when the links are heterogeneous.