无线Ad hoc网络基于竞争时延方差的TCP定时机制

TCP Timing Mechanism based on Variance of Contention Delay in Wireless Ad hoc Networks

在无线Ad hoc网络中,严重的竞争干扰使得往返时延(RTT)的波动十分剧烈,单一基于RTT样本且每个样本被赋予相同权重的传统超时重传时间(RTO)估计方法是不准确的。本文提出一种基于竞争时延方差的RTO估计方法,该方法通过对比网络竞争程度和RTT波动情况,为RTT样本赋予不同的权重,从而更加合理地更新RTO及TCP的发送状态。NS-2仿真结果表明,本文提出的策略能够显著提高吞吐量和时延等TCP性能。

In wireless ad hoc networks, the round trip time（RTT） fluctuates severely due to serious contentions and interference. Thus, the conventional retransmission timeout（RTO） estimation which is solely based on RTT sample and each sample is given same weight is not accurate in ad hoc networks. In this paper, we propose a novel RTO estimation based on the variance of contention delay. By comparing the degree of contention with the RTT fluctuations, the proposed method gives a different weight to each RTT sample, and thus updating RTO and TCP sending state more reasonably. NS-2 simulation results show that the proposed strategy can significantly improve the TCP performance of throughput and delay.