多跳无线与有线混合网络中TCP性能改进研究综述

Survey of TCP Improvement over Multi-Hop Wireless and Wired Hybrid Networks

多跳无线与有线混合网络中,数据流通过的传输媒体各不相同,这些差异会严重影响TCP性能.为了提高有线与无线混合网络中TCP协议的性能,研究者对混合网络TCP协议进行了大量的研究,主要是通过修改标准TCP协议,使之适合于混合网络环境,设计方法主要有分层设计与跨层设计两种.分析了多跳无线与有线混合网络的特点;探讨了多跳无线与有线混合网络中影响TCP性能的主要因素、TCP所要解决的主要问题,以及改进TCP性能面临的难点;对当前改进混合网络中TCP效率、公平性等方面的研究成果进行了分析和总结,并指出了多跳无线与有线混合网络中TCP进一步研究的重点.

Standard TCP （Transmission Control Protocol） has limitations when it is used in wired and multi-hop wireless hybrid networks environment. Transmission media carrying data present a wide range of characteristics in multi-hop wireless and wired hybrid networks, some of which may cause a degradation of TCP performance. Much work has been conducted on the performance of TCP under different networks environment. A lot of efforts are made to improve the performance of TCP over wireless and wired hybrid networks. Most of them adapt TCP to multi-hop wireless and wired hybrid networks by modifying the standard TCP. Two main approaches are proposed： one focuses on the modification of one layer of OSI model, namely layered design. and the other improves TCP performance by modifying multi-layer, namely cross-layer design. In this paper, some different characteristics between wireless networks and wired networks are analyzed, then some key factors that influence TCP performance under wireless networks are discussed, and some difficult issues are pointed out to improve the performance of TCP over wired and wireless hybrid networks. Some research work about TCP performance under wired and wireless networks environment is analyzed and summarized. Finally, some possible research trends of the development of TCP over multi-hop wireless and wired hybrid networks in the future are proposed.