A Cross-Layer For TCP Congestion Control Mechanism Based On Wireless Network

With the rapid development of wireless technology, wireless networks including wireless access network, satellite network, mobile ad hoc network and sensor network have become the important part of the Internet. The traditional cellular mobile communication system is experiencing the generational evolution, and in the meantime, various new radio access technologies (RATs) come forth. Wireless communication networks is evolving towards diversification of access method, high speed of data transmission, universal mobility and all IP (Internet Protocol)i, integration, and will become an all-inclusive, ubiquitous and omnipotent next generation wireless networks. The next generation wireless networks provide the seamless handover and roaming between heterogeneous networks, support multi- hop self-organizing access and cooperative relaying technology, and so on. Though increasing under Gilder is law, the network bandwidth cannot meet the requirement of the network applications.At present, TCP protocol has been widely used both in the Wireless networks and Wire networks. Because of the wireless network environment existence of the problems of noise disturbance and fading channel, At the same time the error of data frame transmission is randomly appear, and statiscal characteristics of it changed over time, So seriously reduces the TCP protocol timeliness and effectiveness in testing/control. Because TCP was originally designed for wired networks, so TCP always packet loss or overtime as caused by network congestion, this will make it not to very good performance in the wireless link.View of the above problems, there are main works as follows:1. This paper summarize the development and evolution of wireless networks and according to the characteristics of wireless network, research status and the problems facing us has carried on deeply analysis collated and summarized. And investigated the idea and approaches of cross- layer design of different layers of the transmission control protocol/Internet protocol (TCP/IP) Protocol stacks, and analyzed the Principle of cross-layer design and the methods to improve system performance.In the paper, a kind of based on wireless networks cross-layer perception mechanism TCP is proposed, LCT-TCP (Link Condition Trigger TCP). It make TCP can quickly perceive the information of data link layer. The connection between terminal and proxy is wired and the connection between the proxy and the server is wireless. When the agency found the data link layer of frame error rate change will transmit the information of error frame rate to the transport layer quickly. The simulation results show that proposed scheme to significantly improve speed of the transport layer perception data link layer information of error frame rate. TCP protocol can more quickly and reasonable make the right adjustment according to the wireless network situation.2. Analyzes the end-to-end TCP flow change rule in wireless network, network flow exist autocorrelative characteristics. In this paper adopts the method of cross-layer design, the transport layer according to perception of data link layer information of error frame rate to predict the current network bandwidth, a kind of based on bandwidth prediction TCP congestion control mechanism is put forward.Finally, simulate the improved TCP protocol, using the simulation tool, the results shows that the based on bandwidth prediction TCP congestion control mechanism can further improve the utilization rate of network bandwidth and to improve network performance.