Algorithm Research Of TCP Congestion Control Over Wireless Network

TCP protocol runs well in Internet. However, TCP performance declines remarkably in wireless networks. Therefore, how to improve TCP performance in wireless networks becomes an important research issue. This paper researches TCP-Friendly congestion control mechanism over cellular wireless networks and ad hoc networks.Firstly, the performance of TCP protocol and friendliness between TCP flow and UDP flow are analyzed in this paper. And then different characteristics of TCP data flow are researched over cellular wireless networks. Furthermore the transmission function between different TCP versions is contrasted and major factors affecting TCP function are summarized in this paper.Based on these experiments and analysis above, a kind of congestion control algorithm faced TCP-Friendly is proposed. Then this paper makes use of two error division modes to estimate key reasons leading to losing packs. And different strategies are used to manage lost packs of different reasons. Comparing with LDA+ mechanism, the experiments show that new algorithm performances better in the congestion control of wireless networks.Subsequently, a congestion control algorithm based on receivers'feedback is proposed in this paper. The new algorithm estimates the current bandwidth by information sending by receivers to renew congestion window. Also experiments show performance of the new algorithm is better than the performance of TCP-Newreno protocol. That's to say the new algorithm is more fit for wireless networks.At last, this paper proposes a new congestion control algorithm in Ad hoc networks named TCP-Impro. TCP-Impro uses selecting acknowledgement mechanism in order to decrease the load of networks and probability of collision. Consequently, the utilization of bandwidth is improved. Finally, experiments show that TCP-Impro can improve the performance of TCP over ad hoc network.