一种新的固定速率分层组播拥塞控制协议

提出了一种新的固定速率分层组播拥塞控制算法FLMCC。组播会话中的每层按照固定速率发送数据包。各接收端根据估计的期望速率累计订购数目不等的层，从而获得不同的吞吐量。为准确估计期望速率并实现TCP友好性，各接收端采用在接收端实现的窗口机制，即在每层独立维护拥塞窗口，利用GAIMD算法调整窗口，并根据窗口值计算期望速率。为测量RTT，采用了一种精确测量和粗略测量相结合的策略；为避免RTT精确测量时产生的反馈内爆问题，采用了基于随机定时器机制的反馈抑制策略。协议实现简单。仿真表明，算法具有良好的TCP友好性、响应性和协议内公平性，且链路利用率高。

Fixed-rate Layered Multicast Congestion Control

A new fixed-rate layered multicast congestion control algorithm called FLMCC is proposed. The sender of a multicast session transmits data packets at fixed rate on each layer, while each receivers obtain different throughput by cumulatively subscribing to deferent number of layers based on their expected rates. In order to provide TCP-friendliness and estimate the expected rate accurately, a window-based mechanism implemented at receivers is presented. To achieve this, each receiver maintains a congestion window on each layer, adjusts it based on the GAIMD algorithm, and an expected rate from the congestion window calculats. To measure RTT, a new method is presented, which combines an accurate measurement with a rough estimation. A feedback suppression based on a random timer mechanism is given to avoid feedback implosions during the accurate measurement. The protocol is simple in its implementation. Simulations indicate that FLMCC shows good TCP-friendliness, responsiveness as well as intra-protocol fairness, and provides high link utilizations.