Zhang, Zhi-LiDong, Yingfei2020-09-022020-09-022000-12-05https://hdl.handle.net/11299/215448Video streaming across wide-area backbone networks using proxy servers is an important component of emerging global multimedia content delivery networks. In this paper we propose and develop a novel proxy-assisted video streaming technique---referred to as the staggered two-flow video streaming technique---for delivering videos across a best-effort wide-area backbone network from a central server to a video proxy server. The objective of the proposed video streaming technique is to provide controlled video quality assurance by taking advantage of the disk space at the proxy server, while circumventing the disk I/O bandwidth limitation at the proxy server in the mean time. Our technique is designed for stored videos that use compression schemes with inter-frame dependency, such as MPEG. Using theproposed staggered two-flow video streaming technique, a video stream is delivered in two separate substreams (referred to as flows): a flow containing the essential portion of the video (e.g., I frames) and the other containing the less essential portion of the video (e.g., P/B frames.) Both flows are segmented, and transmitted across the best-effort wide-area backbone networkusing different mechanisms. By delivering the I frame flow one segment ahead of time and caching the segment at the proxy server, we use a modified TCP with application-level throughput control (called controlled TCP or cTCP) to ensure the reliable transmission of the I frame segments while meeting their delivery deadlines. In contrast, the less essential flow containing the P/B frames is streamed unreliably (using RTP/UDP) in real time, and merged with the cached I frames by the proxy server using its memory buffer. We also develop rate adaptation and control schemes to dealwith transient and persistent network congestion. Simulations are conducted to demonstrate the efficacy of the proposed staggered two-flow video streaming technique.en-USReport