Research And Performance Optimization Of MANET DSR Protocol

A mobile ad hoc network (MANET) is a multi-hop temporary autonomous system of mobile nodes equipped with wireless transceivers and receivers. As it does not depend on fixed network infrastructure, and has no central controlling node as well as good in resisting destructions, it is applicable to many situations that have difficulties in wiring networks. Based on these special advantages, MANET plays an important part in military applications, and it also has a good prospect in civil applications. DSR protocol is an on-demand routing protocol that is specifically designed for MANET. It attracts widely attention because of its advantages such as its simplicity, low network overhead, low algorithm complexity, supporting unidirectional routes and so on. So DSR protocol will probably play an important role in future MANET applications.Based on analyzing the characteristics of the ad hoc network, and studying the machnism of the DSR protocol and evaluating the present relative researches, the Flow extended mechnism and DSR-ERAD are proposed in this paper, in which Flow extended mechanism has reduced the overhead of the DSR source route in data packetes'header and DSR-ERAD is an optimization to DSR with active discovery to the invalid routes in route cache.In DSR protocol each packet to be routed carries in its header the complete, ordered list of nodes through which the packet must pass, this increases the routing overhead of DSR protocol. The Flow extended mechanism proposed by this paper improved the performance of DSR. The mechanism introduced the hop-by-hop technique in AODV into DSR, it reduced the routing overhead of DSR, and meanwhile it raised the efficiency of DSR. Results obtained by Network Simulation (NS) shows that the DSR with Flow extended mechnism performs effectively in terms of successfully packet delivery ratio, routing overhead and end-to-end delay.In order to improve DSR in not timely updating error routes in route cache, DSR-ERAD protocol introduced the connectivity manage mechanism into DSR protocol, and utilized the hello message and neighbor table flexibly. When the network topology changes rapidly, the nodes in DSR-ERAD can find error routes in its route cache in time; when the network topology changes slowly, the nodes in DSR-ERAD can scale down the number of hello messages broadcasted. Results obtained by Network Simulation (NS) shows that DSR-ERAD has better performance than DSR.The research of routing protocol in this paper needs to be simulated on NS platform, but there are not comprehensive instructions of how to add a new wireless routing protocol to be simulated on NS platform and how to analyze its performance through the results. Such a detailed instruction has also been given based on simulation practice in this paper.