Minimizing Application-Level Delay of Multi-Path TCP in Wireless networks: A Receiver-Centric Approach

Abstract

Multi-Path TCP (MPTCP) has attracted much attention as a promising technology to improve throughput performance of wireless devices that support multi-homed heterogeneous networks. Although MPTCP provides significant increase in network capacity, it may suffer from poor delay performance since the delay tends to be aligned with the worst-performing path: packets delivered through a short-delay subflow have to wait in the reordering buffer for packets being transmitted over a long-delay subflow. In this paper, we investigate the applicationlevel delay performance of streaming traffic over MPTCP, and develop an analytical framework to take into account nonnegligible network queuing delay and the interplay of congestion control between multiple subflows. We design a simple thresholdbased subflow traffic allocation scheme that aims to minimize user-level delay and develop a receiver-centric traffic splitting control (R-TSC) that can be tuned to user preferences. The clientside R-TSC solution facilitates incremental deployment of lowdelay streaming service over MPTCP. Through simulation and testbed experiments using commercial LTE and WiFi networks, we demonstrate significant performance gains over the standard MPTCP protocol.