Enhanced TFRC to improve the quality of multimedia streaming service

TFRC (TCP-friendly Rate Control) is designed to mainly provide optimal service for unicast applications such as multimedia streaming in the best-effort Internet environment. TFRC smoothly changes transmission rate while competing fairly with TCP by using an equation on the modeling of TCP Reno to adjust the transmission rate. However, TFRC inherits RTT-unfairness problem of TCP Reno which severely affects the performance of the long-RTT flows. Another disadvantage inherited from TCP Reno is overshooting problem of slow-start mechanism. A large number of packet losses within a RTT are inevitable because of overshooting. These losses degrade the quality of streaming video. In this paper, we suggest two enhancements of TFRC in order to increase the quality of multimedia streaming service. Firstly, we propose a bandwidth estimation method to achieve more equitable bandwidth allocations among streaming flows which compete for the same narrow link with different RTTs. Secondly, we propose a new slow start mechanism to decrease burst packet losses caused by overshooting. The simulation results have shown that our proposal can achieve a better RTT-fairness and reduce burst packet losses of slow-start as compared to the original TFRC.