Ad-hoc网络传输控制协议研究

Research on transmission control protocol in Ad-hoc network

Ad-hoc网络是一种无线网络,它在通信时通常使用TCP协议。这种协议是为有线网络开发的,直接应用将导致错误地启动拥塞控制,这会降低网络的通信效率,因此必须修改TCP协议,提高它在无线网络环境中的工作效率。本文分析Ad-hoc网络中TCP的性能表现,在Vegas的基础上分析其拥塞控制机制,修改该部分的实现算法,进而提出VegasE,利用NS2网络模拟软件对Tahoe,Reno,Vegas和新的VegasE进行模拟测试并对比结果。通过对比可以发现Vegas和VegasE在整体上明显优于Tahoe和Reno;VegasE在一些方面优于Vegas,但在另一些方面表现不佳,这说明需要进一步研究Vegas并对其做出更细致的修改,以便提出更好的通信协议。

Ad-hoc network is a kind of wireless network,and it usually uses Transmission Control Protocol (TCP) in communicating. Because this kind of protocol was developed for wired network, it can’t adapt to wireless network environment.Its direct application will result in starting congestion control in an error manner and reduce network communication efficiency, therefore the TCP protocol must be modified to improve its work efficiency in wireless network environment. This paper analysed the performance behavior of TCP transmission control protocol and its congestion control mechanism on the base of TCP Vegas, modified the implementation arithmetic of TCP Vegas and put forward the VegasE protocol,then simulated and tested Tahoe, Reno, Vegas of main TCP protocols and the new VegasE protocol using NS2 network simulation software, and compared with results. By comparison, it was found that Vegas and VegasE protocols were obviously better than Tahoe and Reno protocols on the whole; VegasE protocol was better than Vegas protocol in some aspects, but it behaved worse in other aspects.This indicated that it is needed to make much research on Vegas protocol and modify it with more particularities so that a better communication protocol can be put forward.