Study On The Improvement Of AOMDV Protocol In Mobile Ad Hoc Networks

The Mobile Ad Hoc Network (MANET) is a non-center and self-organizationnetwork, whose feature is different from wired network and traditional wirelessnetwork. Routing protocol is one of the key technologies to realize MANET. Thetopology structure of MANET varies frequently, so the stability of the selected routeis crucially important. How to improve the routing reliability is one of the main aimsof the routing protocol research. In this paper, multipath routing protocols forMANET are studied in depth, and the classification and basic structure of multipathrouting protocols is introduced in detail, and the advantages and the main problems ofmultipath routing research are discussed.In the multipath routing protocols of the MANET, AOMDV protocol performswell, but there is a shortcoming in the protocol. The only characteristic consideredwhen choosing a path is the number of hops and path stability is ignored. There is aninherent characteristic of channel fading in real wireless communication environment,which presents a high demand on the stability of the selected route. In order to copewith the fading of channel effectively, an improved scheme of AOMDV protocol isproposed in this paper. In the route discovery process, ANFD is combined with thehop-count criterion from AOMDV to serve as a metric with which to select short butstable paths instead of simply choosing the shortest path. So, the improved schemetakes into account stability and length to improve overall path quality. In the routemaintenance process, it uses predicted signal strength to trigger a handoff before afade occurs, reducing the connection failure rate. The breaking link AFD is recorded,so that it maybe reutilize once out of the fade.In order to demonstrate the superiority of the improved scheme of AOMDVprotocol, the theoretical analysis of the improved scheme is made in this paper. Underthe established network model, the probability density functions of the lifetimes of asingle path and multiple paths are derived and the performances in terms of routingcontrol overhead and network throughput are analyzed. Finally, using the networksimulator NS2, under the settings of network environment, a contrast is made with theperformance of the AOMDV protocol and its improved scheme, verifying thesuperiority of the improved scheme. Simulation results show that the network performance of the AOMDV protocol, including network throughput, averageend-to-end delay, routing control overhead and packets delivery ratio, is improvedthough the scheme.