The Cross-layer Improvement On TCP Over Manet

With the development of mobile communication technology and the Internet, the wireless network technology occupies more and more important position of the Internet, due to its unique advantages. While the next generation of mobile communications network is an IP-based network. The report pointed out that currently more than90%of the IP network service is based on the TCP protocol. With the increasing demand for wireless network business, there is a higher demand for wireless network performance and quality of service. Therefore, the applied research to enhance the performance of TCP protocol in mobile ad hoc networks (MANET) is very meaningful.TCP protocol is designed and optimized based on the wired network, Because the packet loss is caused by congestion, so TCP conduct the network traffic control. However, in a mobile ad hoc network hidden node and exposed node problems will lead to a conflict of the MAC layer frequent occurrence competition, resulting in the routing of the interrupt, triggered TCP interrupt for a long time and retransmission. Does not modify the TCP protocol used in mobile ad hoc networks, will lead to serious performance degradation.Order to optimize the performance of the MANET network in TCP, two cross-layer design optimization:MAC layer protocol for TCP protocol design of three states:connected state, disconnected state and restore the state. The interrupt signals generated by the IEEE802.11protocol LBN transitions between states. Each state corresponds to a TCP packet control mechanisms, thus completing the TCP protocol based on underlying link-state reaction, the agreement cross-layer optimization.AODV routing protocol, routing intermediate hops, recorded in the routing process of establishing the TCP protocol to send the maximum and minimum values of the window and then hop limit. Thus avoiding the TCP protocol window is too small, resulting in a waste of bandwidth and the window is too large due to network congestion.The detailed analysis of the performance issues in mobile ad hoc networks, the TCP protocol proposed two cross-layer optimization of MAC layer and routing protocol by NS2simulation and analysis of the program, verify the effectiveness of the improved.