无线自组网TCP定时器的分析与改进  

Analyzing and improving the TCP timer in wireless ad hoc networks

作　　者：陈志刚[1] 李庆华[1] 邓晓衡[1] 黄国盛[1] 

机构地区：[1]中南大学信息科学与工程学院,长沙410083

出　　处：《高技术通讯》2010年第6期577-584,共8页Chinese High Technology Letters

基　　金：863计划(2008AA7034060B);国家自然科学基金(60873082);总装预研基金(9140A15030308QT4801)资助项目

摘　　要：仿真并分析了无线自组网TCP数据流重传超时(RTO)与传输往返时间(RTT)的关系,指出在RTT剧烈振荡的无线多跳网络环境下RTO的变化会滞后于RTT的变化,导致根据RFC2988标准做出的RTO估计不准确。针对这种情况,利用网络演算理论推导出了TCP数据流的最小延迟上界(MDUB),并以此改进了RTO的估计算法。仿真实验表明,基于最小延迟上界的RTO估计算法能准确地估计数据包的最小传输往返时间上界,减少TCP数据传输中的伪重传,提升无线环境下TCP协议的性能。Based on the simulation and analysis of the relationship between the retransmission time-out （RTO） and the roundtrip time （RTT） of TCP data flow in wireless ad hoc networks, the paper points out that the RTO estimation according to the RFC 2988 is not accurate as the variation of the RTO value is behind the variation of the RTr value over wireless ad hoc networks. And inview of this, it derives the TCP transmission minimum delay up bound （MDUB） using the network calculus theory and then improves the RTO estimation algorithm based on the MDUB. The simulation results show that the MDUB-based RTO algorithm can estimate TCP minimum transmission round-trip time up bound accurately, so the TCP data flow based on the MDUB timer can reduce the TCP spurious retransmission and then promote the TCP performance in wireless ad hoc networks.

关 键 词：无线自组网 802.11 TCP定时器 网络演算 最小延迟上界 

分 类 号：TN925[电子电信—通信与信息系统]