Research And Realization Of Quality Of Service In The Transmission Of Streaming Media

Internet based on TCP/IP protocol is a kind of Packet Switch Network, Internet is too weak to satisfy the multimedia transmission demand. Therefore, It has been the important task to research a kind of TCP-friendly transport control protocol which fit to the real-time flows and control the congestion effectively, It has significant meanings for the development of streaming mediaFirstly, the paper analyses the background and current status of streaming media; we analyze RTP/RTCP protocol in detail, and discuss its application in congestion control areas. Because the precondition of congestion control is how to get the parameters of qos dynamically. If this can not be ensured, no matter how excellent arithmetic is a waste. The current research about it is mainly about RTP/RTCP protocol.Two TCP-friendly congestion control mechanism, which are widely used, will be concluded in the thesis. One kind is based on the exploration, the other is based on the TCP throughput model. The advantages and shortcomings will also be compared. The sending rate of the former can emerge the biggish dithering and not fit to the applications of the real-time multimedia, and the scheme based on model is much more fit for streaming media transmission. On the base of analysis TFRC algorithm, an improved scheme is presented. The result of NS network simulation experiment proves that the new algorithm has sending speed smoothness and is TCP-friendly. One kind is based on the exploration, the other is based on the TCP throughput model. The sending rate of the former can emerge the biggish dithering and not fit to the applications of the real-time multimedia. We study the congestion control mechanisms based on the TCP throughput model. Among of them, the TFRC algorithm which based on Padhye TCP throughput model has been the standard RFC 3448. The throughput of the algorithm changes slowly and fit to the applications of the real-time multimedia while maintaining TCP friendliness. It is a hot research topic. On the base of analysis TFRC algorithm, an improved scheme is presented. The result of NS network simulation experiment proves that the new algorithm has sending speed smoothness and is TCP-friendly. At the same time, the policy of matching the average receive-rate to the average of the send-rate is presented. The result of NS network simulation experiment proves that the matching policy improves the smoothness of the streaming media significantly Compared to TFRC, shows a better performance of real-time, has less jitter, while maintaining the good performance of TCP-Friendliness.