Performance Evaluation of Concurrent Multipath Video Streaming in Multihomed Mobile Networks

High-quality real-time video streaming to users in mobile networks is challenging due to the dynamically changing nature of the network paths, particularly the limited bandwidth and varying end-to-end delay. In this paper, we empirically investigate the performance of multipath streaming in the context of multihomed mobile networks. Existing schemes that make use of the aggregated bandwidth of multiple paths can overcome bandwidth limitations on a single path but suffer an efficiency penalty caused by retransmission of lost packets in reliable transport schemes or path switching overheads in unreliable transport schemes. This work focuses on the evaluation of schemes to permit concurrent use of multiple paths to deliver video streams. A comprehensive streaming framework for concurrent multipath video streaming is proposed and experimentally evaluated, using current state-of-the-art H.264 Scalable Video Coding (H.264/SVC) and the next generation High Efficiency Video Coding (HEVC) standards. It provides a valuable insight into the benefit of using such schemes in conjunction with encoder specific packet prioritisation mechanisms for quality-aware packet scheduling and scalable streaming. The remaining obstacles to deployment of concurrent multipath schemes are identified, and the challenges in realising HEVC based concurrent multipath streaming are highlighted. 1. Introduction One of the main challenges in video streaming is to intelligently adapt the stream in response to dynamically changing network conditions in a way that attempts to minimise the distortion effect on the received video of adverse network conditions. H.264 Scalable Video Coding (H.264/SVC) [1], the scalable extension to the H.264 Advanced Video Coding standard (H.264/AVC) [2], has emerged as a promising means of adapting a video stream to prevailing network conditions but has yet to be adopted on a large scale for delivery of streamed video content. In H.264/SVC, a video stream consists of a number of scalable layers, each of which can be dropped either partially or in its entirety to adapt to changing network path conditions. Adapting an H.264/SVC stream to a change in the available bandwidth on a single wired network path is a well-understood problem; solutions that drop entire scalable layers [3] or individual packets from a layer [4] have both been previously proposed. H.264/AVC is the current, widely deployed, video encoding standard, and its extensions such as H.264/SVC represent the current state of the art. However, work on a replacement for the H.264 family of encoding