TCP Congestion Control Enhancements for Streaming Media
Hideyuki Shimonishi, Hama Takayuki, Tutomu Murase · 2007
Video streaming, including VOD (Video on Demand) services, over the Internet has been rapidly becoming popular. Although RTP/UDP has been considered as a standard transport protocol for video streaming, TCP is already widely used for VOD services because of its flexible accessibility to user clients beyond firewalls or NATs. However, poor video quality, for example, frequent pause of playback, due to TCP congestion control has been pointed out. In this paper, we propose an enhancement for TCP congestion control algorithm, which we call TCP-AV, to realize stable video streaming using TCP. TCP-AV incorporates two principal mechanisms, (i) dynamic TCP parameter tuning to stabilize TCP throughput around the target rate, and (ii) temporal target rate reduction to avoid severe congestion. Simulation results show that TCP-AV provides better rate control for maintaining target rate, and thus better video quality, even when the network is shared by many co- existing flows. In our scenario for a metropolitan VOD service, TCP-AV accommodates roughly 3 times larger number of VOD flows compared to TCP-Reno.