无线网络中TCP友好流媒体传输改进机制

为保持无线网络中多媒体业务对TCP的友好性，提出了一种适用于无线网络的动态自适应的流媒体传输速率调节机制。该机制通过在接收端区分网络拥塞丢包和链路错误随机丢包，准确判断网络的拥塞状况结合接收端缓存区占用程度，自适应实施多级速率调节，实现了TCP流友好性和流媒体服务质量（QoS）的折中。由于准确区分出无线链路误码丢包和动态调整流媒体QoS要求，该机制能维持较高的网络利用率。仿真实验结果显示在连接数为2和32，链路误码率从0到0．1变化时TCP,TFRC和吞吐量幅度下降幅度较大，WTFCC幅度下降相对较慢，最大相差达2M；在网络负载重时，尽管链路误码率较低，WTFCC区分链路错误与拥塞丢包，因此，端到端丢包率高于TCP和TFRC，但整体传输吞吐量也高于两者。归一化吞吐量显示WTFCC对TCP流友好。

TCP-friendly streaming medium transmitting mechanism in wireless network

To maintain Streaming media services flows friendly to TCP flows and hold the QoS of the streaming service in wireless networks, an adaptive rate control mechanism was proposed. Packet loss between network congestion and wireless link error was distinguished to get the accurate state of the networks by the receiver. Occupation of the receiver buffer, which reflected how long the temporarily stored streaming medium data could be played, was also combined into this algorithm. And tradeoff between TCP-friendly and QoS of streaming media service was achieved through multi-level rate adjustment according to packet loss rate of congestion and queue length of receiver. The results of simulations show that good throughput was gained compared with TCP and TFRC, at most reaching 2M, in condition of 0-0.1 link drop rate, 2 and 32 conncections. As link error and congestion was seperated by WTFCC, therefor, end to end packet drop rate was higher than TCP and TFRC, and also of higer throughput. Nomalized throughput indicated that WTFCC was friendly to TCP.