基于QPID-AVQ的组播拥塞控制机制

针对现有多媒体组播拥塞控制协议的不足，提出基于QPID虚拟队列管理的组播拥塞控制机制QPID-MCC。QPID-MCC在瓶颈路由器中采用QPID-AVQ队列管理策略，结合显式拥塞指示(ECN)，按照一定的概率标记新到分组。接收端依据标记概率计算期望的TCP友好速率。发送端依据接收端的反馈信息并结合多媒体的最小带宽需求调整发送速率。仿真结果表明，QPID-MCC具有平滑稳定的发送速率、较好的公平性和较快的拥塞响应速度，并能满足最小带宽要求，保证多媒体业务的服务质量。

Multicast Congestion Control Mechanism Based on QPID-AVQ

To settle the problems existing in multimedia multicast congestion control protocols, a multicast congestion control mechanism based on QPID-AVQ is proposed, termed QPID-MCC. QPID-MCC introduces QPID-AVQ queue management strategy and Explicit Congestion Notification(ECN) technology in the bottleneck router, so that enables the router to mark the new arriving packets in accordance with a certain probability computed by QPID-AVQ algorithm. The receivers calculate the expected TCP-friendly rate based on marking probability, and the sender adjusts the sending rate according to the feedback information from the receiver and the minimum bandwidth requirements of multimedia services. Simulation results show that QPID-MCC has a smooth and stable sending rate, good fairness and fast response to congestion, and can ensure minimum bandwidth requirement of multimedia services.