多跳对基于802.11的Ad Hoc网络TCP流公平性的影响

Multi-hop is Influence on TCP Fairness of 802.11 Based Ad Hoc Networks

多跳是Ad Hoc网络主要的特点,也是很多问题(如TCP流不公平、不稳定以及吞吐量下降等)产生的原因。文中基于NS2仿真平台研究了跳数及接入时间对TCP流公平性的影响,给出了不同TCP流的信道接入能力,深入分析了多跳TCP流公平性下降的原因,并在此基础上提出了改进公平性的建议。研究的结果表明,不同跳数的TCP流共存时,跳数较少的TCP流会占优甚至垄断信道。当跳数相同时,提前接入的TCP流会占优甚至垄断信道。

Multi-hop is the main characteristic as TCP flow unfairness, instability and throughput of the ad hoc network, and also the cause for many problems（such decrease）. By using NS2 simulator, the influence of hops and access time on TCP flow fairness is studied. The channel access ability of TCP flows with different hops is also given. Finally, the advice about how to improve TCP flow fairness is presented. And the research result suggests that the TCP flow with small number of hops would monopolize the information channel and if the TCP flows have same number of hops, the channel would be monopolized by the access one in advance.