Abstract: In this paper，we propose a new TCP scheme，called TCPW CM，which is a revision of TCP Westwood.Its key component is CE configured router which is based on ECN and classifies the level of congestion into three regions：no-load，low-load and high-load.CE and TCPW work together to insure differentiating the wireless packet losses from the congestion packet losses effectively.The experiments show that TCPW CM achieves significant improvements in throughput over TCP Westwood and TCP New Reno and maintains the fair and friendly behavior with respect to other TCP flows.

Key words: congestion control, bit error rate, TCP Westwood, XCP and VCP, RED and ECN

摘要： 针对TCP Westwood（简称TCPW）拥塞避免算法在高误码率无线网络环境下不能区分丢包原因和性能仍显不足的问题，在中间节点提出了一种简单有效的拥塞标记机制，称为CM（Congestion Marking），它是基于ECN的，将拥塞程度划分为无拥塞、轻度拥塞和重度拥塞三种情况，与TCP Westwood算法结合，形成了基于ECN的TCPW CM算法，能有效地区分拥塞丢包和无线丢包。仿真实验表明，改进后的算法在高误码率情况下提高了网络利用率和吞吐量，同时仍具有良好的公平性和友好性。

关键词: 拥塞控制, 误码率, TCP Westwood, XCP和VCP, RED和ECN