基于RTCP的移动流媒体研究

A study of Mobile Streaming Media Based on RTCP

在移动网络发生拥塞时,由于传统的TCP友好速率控制机制(TFRC)存在丢包率偏差问题,导致移动流媒体服务器不能获取正确的网络状态信息,从而过度调节发送速率。为了解决问题,提出一种基于RTCP的改进机制。基于移动网络的特性,机制结合时间分布均匀化的RTCP发送机制缓解RTCP初始化洪泛,通过分析RTCP报告,在流媒体服务器端正确区分出网络拥塞丢包和移动网络随机误码丢包,以获得正确的丢包率,最终实现数据发送速率的自适应调节。利用NS2网络仿真软件进行仿真,结果显示该机制比TFRC机制更具备适应网络波动的能力,并能维持较高的网络利用率。移动流媒体的服务质量得到提升。

Because of the problem of conventional TFRC mechanism concerning incorrect packet loss rate, when it is applied to mobile congestion networks, the mobile streaming media sever cannot get the accurate information of the networks condition and thus leading to inappropriate rate control. To resolve the problem, an improved mechanism based on real - time transport control protocol （RTCP） was designed. According to the inherent wireless network characteristics, this mechanism can get the correct packet loss rate to achieve the purpose of adaptive data rate adjustment by sending RTCP in a uniformly distributed periodic and distinguishing packet loss between network congestion wireless link error effectively. Simulation analysis was made between the improved mechanism and the current mechanism. Simulation in NS2 showed that this mechanism had the ability to adapt to fluctuations in the network conditions and maintain higher network utilization. Therefore, it imoroved the quality of service of mobile streaming media.