Performance Analysis And Protocol Improvement Of TCP In Mobile Ad Hoc Networks

TCP in the Ad Hoc networks is analyzed and improved in this paper. Mobile Ad hoc networks are completely wireless no-center and self-organized networks with mobile hosts, in which the topology rapidly changes due to the movements of mobile hosts. This frequent topology change may lead to sudden packet losses and delays. Classical Transport Control Protocols, which have been designed for reliable fixed networks, misinterpret this packet loss as congestion and invoke congestion control, leading to unnecessary retransmissions and loss of throughput. To overcome this problem, Improved-TCP scheme is proposed so that the source can distinguish disconnection failure from network congestion.After understanding about the principles and mathematics of classical TCP, the results why classical TCP performs poorly in wireless Ad Hoc networks are discussed. Several solutions have been proposed and compared to address the known problems that TCP faces when running over wireless networks.Based on the study of several solutions about TCP and route prediction in mobile Ad Hoc net works, we propose a new TCP scheme, called Improved-TCP, which is capable of distinguishing the wireless packet losses from the congestion packet losses, without feedback from networks, and have implemented it in VC++.Improved-TCP was studied and simulated in the network simulator OPNET. Results from the simulations show that Improved-TCP compared with classical TCP can effectively improve speed with small variances of throughput and delay. As views and conclusions contained in this document, Improved-TCP does not only maintain the semantic consistence for end to end, but also have a better performance in wireless Ad Hoc networks. Additionally, there are several limitations exist in this scheme, e.g. the gain of important parameter are still studied theoretically.