Research On Multicast Routing Protocols Of Ad Hoc Networks And OPNET Simulations

Mobile Ad hoc Network (MANET) is a multihop provisional autonomy system that is made up of a group of portable terminals with wireless transmitter, in which mobile nodes communicate with each other without the required intervention of any centralized access point or fixed infrastructure. It will be widely used in critical environment such as military or civilian emergency operations because it has many advantages such as it yarely, quickly and absolutely distributed etc. MANET routing protocol has to deal with the dynamic topology, unidirectional link, limited wireless bandwidth and capability-constrained of mobile nodes, etc. So, the MANET routing protocol must play a more important role than others.Multicasting is the transmission of datagrams to a group of hosts identified by a single source address and hence it is intended for group-oriented computing. In a typical MANET, multicasting is very important. On the one hand, Ad hoc user need to cooperate with each other;and on the other hand, it is important means of make the best of limited wireless channel .In view of the feature of MANET, now many kinds of multicast routing protocol are proposed, and some of them have been tested in special wireless network with small scale.In this thesis, firstly we briefly summarize and compare the existing multicast routing protocols based on the characteristic of MANET, and give the analysis of MAODV protocol (Multicast Ad Hoc On-Demand Distance Vector Routing Protocol) in detail. Then the design architecture of MANET multicasting protocol and the solution to the key technologies on OPNET network simulator are presented. Secondly, we describe the improvement and modification about MAODV for expansibility and reliability. We proposed a protocol named DMAODV (Distensible Multicast Ad Hoc On-Demand Distance Vector Routing Protocol) that is enhanced the expansibility and haleness of protocol,it is effectively solve the question about blindness broadcasting of multicasting control packets on MAODV, it adopts a flooding of self-repression to send control packets that is greatly reduce the broadcast on networks, at the same time overhead is reduced also. We proposed a protocol named RMAODV(Reliable Multicast Ad Hoc On-Demand Distance Vector RoutingProtocol) that is based on a protocol relay concept. It uses new NACK restrain mechanism to prevent NACK storm. RMAODV supports a reliable multicasting suitable for mobile Ad hoc networks by reducing the number of route reconstructions and packet retransmissions. And we conduct plentiful experiments on OPNET simulator about MAODV, DMAODV and RMAODV multicast routing protocols to prove the correctness of our implementation. The simulation shows that the improvement could enhance the performance in the high movement mobile Ad hoc networks. Finally, we give the conclusion of our work and suggestions for future research direction of Ad hoc Mobile Networks.This thesis is supported by National Natural Science Foundation of China (90304018).