Research On Tfrc Protocol For Wired/Wireless Hybrid Environment

In recent years, the network multimedia service develops rapidly. Streaming media service application based on wireless data transmission popularized widely and rate control of streaming media in wired and wireless network becomes more and more important. However, the data transmission has been greatly affected by the characteristics of wireless link which makes the performance of the streaming media service application become much worse.The TFRC protocol is a kind of TCP-friendly congestion control protocol which has a better development in current unicast domain, and the research on TFRC is relatively mature. Since TFRC is originally designed for wired networks, so it can not distinguish between types of packet loss in a wireless network, and the congestion control mechanism is blindly started which may affected the performance of streaming media. Thus, TFRC protocol is needed to be improved and optimized in order to improve the performance of wireless networks and meet the requirements of the users who need the streaming media service a lot in wired/wireless hybrid networks.In order to find out the reason why TFRC can not distinguish between packet losses due to network congestion and those due to wireless link error in wireless networks, the TFRC protocol has been thoroughly studied in this paper, and then the performance of this protocol is tested in wired/wireless network According to the simulation results, two novel methods which named as TFRC-D and TFRC-P have been proposed. In addition, a hybrid mechanism TFRC-DP which combined the TFRC-D’s with TFRC-P’s advantages has been proposed.The improved TFRC-D scheme adopts the information on the one-way delay, and then differentiates between congestion losses and wireless link error losses for hybrid wired-wire less network. It can calculate the correct loss event rate and feedback to the sender, and then the performance of TFRC in the hybrid network can be improved. Meanwhile this thesis also puts forward an improved TFRC-P mechanism which based on the adaptive loss event rate in the receiver. The TFRC-P mechanism uses the loss event rate information in the receiver and a rate adjustment factor to adjust the new loss event rate jointly. The information which fed back to the sender can adjust the sending rate and implement congestion control, and improved performance in the TFRC protocol in hybrid network. The hybrid mechanism TFRC-DP can not only distinguish between types of packet loss in a wireless network, but also improve the performance in the wired/wireless hybrid networkFinally, the performance of the improved TFRC mechanisms has been tested in the hybrid network. The simulation results show that the presented mechanisms have a significant improvement effect in the wired/wireless environments, and outperform traditional TFRC.