基于RTT自适应的无线TCP改进算法

Adaptive algorithm based on RTT for improving wireless TCP performance

针对TCP Reno在无线环境下的性能恶化问题,在研究分析TCP Reno拥塞控制算法问题的基础上,提出一种基于RTT自适应的改进算法。该算法实现了丢包区分的拥塞窗口与慢启动门限调整,减轻了传统TCP由于无法区分拥塞丢包与误码丢包、盲目将拥塞窗口减半带来的性能下降。分析了该算法的可行性,并通过NS仿真对其吞吐量、带宽利用率、公平性等指标进行评估。仿真结果表明,相对TCP Reno,改进算法实现了无线环境下的TCP性能改善,同时具有一定的友好性与公平性。

The performance of TCP is hardly degraded due to very well known problems characteristic of wireless transmissions,so TCP Reno algorithm is researched and an improved algorithm based on adaptive RTT is proposed.The key idea of this improved algorithm adjusts CWND and SSTHRESH for packets losses according to RTT.Consequently,the improved algorithm can differentiate the wireless packet losses from the congestion packet losses effectively.Algorithm analysis shows the feasibility of the new algorithm,its throughput,band with utilization ratio,and fairness is evaluated by NS simulation.Compared with TCP Reno,the simulation results show the improved algorithm achieves significant improvements in throughput and maintains the fair and friendly behavior with respect to other TCP flows.