一种TCP友好的Internet DTV组播发送速率控制机制

当前的Internet没有对流媒体应用提供足够的QoS的保证,同时Internet DTV的组播发送速率必须满足以下两点要求:1)能够自适应网络拥塞的变化;2)能够适应节目码率的要求,因此需要在服务器端进行组播发送速率控制.分析了Internet DTV组播的难点,提出了一种基于缓冲区管理的具有网络自适应特性的组播发送速率控制方法.通过合理地控制发送方的发送速率,既能自适应网络状况的变化,又能满足流媒体实时播放的需求.仿真实验结果表明,该算法在保证服务器端发送缓冲区不溢出前提下,与单纯采用TFMCC方法比较,减少了接收端的平均丢包率,提高了网络电视节目流的传输质量.

A TCP Friendly Multicast Rate Control Mechanism for Internet DTV

The current Internet does not offer enough QoS(quality of service)guarantees or support to Internet multimedia applications.However,there are two requirements of multicast sending rate for Internet DTV at the server:1)it can adapt well to the change of network congestion;2)it can meet the rate requirement of programs.So multicast sending rate control is needed at the server.In this paper the difficulties of Internet DTV stream multicast are analyzed,and then a multicast rate control approach for network DTV stream based on buffer management is given.The algorithm can not only suit for the change of network traffic,but also satisfy the requirement of DTV decoder,by controlling the sending rate logically.The server first calculates the initial sending rate based on the timestamp included in the program streams and then detects the TCP-friendly bandwidth available.Finally taking the initial rate,the bandwidth available and the data occupancy ratio of send buffer into consideration together,a factual send rate can be got.The simulation results show that it can reduce the average packet loss ratio,increase the transmission quality of Internet DTV,and guarantees the sending buffer not to be overflowed,in comparison with the TFMCC method.