基于GEO卫星链路丢包区分的TCP Westwood改进算法

Enhanced TCP westwood algorithm based on loss differentiation over GEO satellite networks

在分析TCP Westwood(TCPW)算法优缺点的基础上,针对其应用于同步轨道(GEO)卫星链路时存在的不足,结合Vegas、Veno及LogWestwood+等改进算法的优势,基于预测的下一时刻的网络带宽,把窗口调整与带宽利用情况相结合,提出了一种新的适合于GEO卫星链路的基于丢包区分的TCP Westwood改进算法。改进算法将每个阶段的窗口调整与带宽估计、网络状态紧密联系起来,结合网络状态和带宽估计判断拥塞窗口的合理性,动态地调整拥塞窗口,使拥塞即将发生时,窗口能及时下降到适宜的水平,尽量避免由于拥塞而导致的分组丢失。仿真结果表明,改进算法提高了TCP westwood在GEO卫星链路中应用时的性能,具有较好的吞吐量、公平性、友好性和较低的丢包率。

The advantages and disadvantages of TCP Westwood （TCPW） algorithm were analyzed, especially when it was used in Geostationary Earth Orbit （GEO） satellite networks. In order to solve the existing problems, a new improved TCPW （TCPW-N） algorithm considering loss differentiation was proposed. TCPW-N algorithm took full advantage of Vegas, Veno and the existing improved TCPW algorithm （ namely LogWestwood ＋ ）, and TCPW-N was suitable for GEO satellite networks. TCPW-N algorithm can judge the packet loss reason, and adjust the congestion window according to the different packet loss reasons and the estimated network bandwidth. Performance analysis and simulation results show that TCPW-N algorithm has effectively resolved the existing problems of TCPW. Compared with TCPW and its other improved algorithm, TCPW-N algorithm has better throughput performance, lower packet loss rate, and better fairness and friendliness when applied to GEO satellite networks.