中文摘要：

网络负载变化的随机性和往返延迟（RTT）的时变性,使得网络传输中存在严重的不确定性,极大地影响了流媒体的服务质量.为此利用模糊逻辑控制原理提出了一种支持流媒体传输的模糊PID速率控制器,有效地补偿了时变不确定性的影响,增强了闭环系统的稳定性和鲁棒性,最大化了网络利用率.模糊PID速率控制器,根据路由器队列长度计算出期望的端系统的发送速率,使得缓存区队列长度保持在目标长度附近,从而避免了网络路由器的拥塞发生.仿真结果表明模糊PID速率控制器可以有效地处理网络的时变性,避免了发送速率的剧烈波动,从而很好地保证了流媒体的服务质量.

英文摘要：

There exist severe uncertainties in network transmission due to randomness of the network load variants,time-varying characteristics of round trip time（RTT）,which seriously affect the quality of service of streaming media.A fuzzy PID rate controller is proposed to support best-effort of streaming media based on fuzzy set theory,which efficiently compensates the time-varying uncertainties and enhances the stability and robustness of the closed loop systems,and realizes maximum bandwidth utilization.Fuzzy PID rate controller can calculate the desired sending rates of the controlled sources according to the router＇s queues,which makes the router＇s queue attain the set point,so the congestion of the router is avoided.Simulation results show that the fuzzy PID rate controller can efficiently deal with the time-varying characteristics and the fluctuation of the sending rates,which can guarantee the quality of service of streaming media.