Research On Performance Of TCP Congestion Control Protocol In Wireless Networks

With the rapid development of computer networks, the share of wireless network access isincreasing. Wireless network provides an anytime and anywhere network access. However, wirelessnetworks has the features of high error, high delay and mobility, they may call TCP congestioncontrol mechanism in error and lead to network performance degradation. Therefore, improvementof TCP congestion control mechanism in wireless network has become a hot issue in the research ofwireless network, and so as in this paper.This thesis firstly depths does the research of wireless network, including wireless networkaccess technologies, features, applications and implementation of key technologies of wirelessnetworks according to a variety of coverage and analysis to the difference between wireless andwired networks. Then the thesis researches the message format of traditional TCP protocol, its workprocedures and changes of states. After that, the thesis depth researches the flow control mechanism,error control mechanisms and eapecially congestion control mechanisms of TCP protocol, and doesanalysis on improved TCP congestion control mechanism. By analyzing the reasons of whywireless network decrease TCP performance, as well as existing improved method of TCPcongestion control mechanism in wireless networks, this thesis proposes an improved algorithmcalled TCP-FR, which judges network congestion based on the trend of relative round trip time.The receiver computes the trend of relative round trip time and divides the congestion levels,dynamic adjusts the size of the window.In order to verify the validity of TCP-FR algorithm, the network simulation tool NS-2is usedin this thesis to establish a wireless networks topology to do simulation and testing on thisalgorithm. Test results show that in high error wireless network, the algorithm can keep TCPcongestion window at a larger stable values and improve the throughput of the wireless network.