The Study And Simulation Of MAODV In Ad Hoc Network

With the development of wireless communication technology and the popularization of portable devices, the need for new mobile telecommunications has been increasingly expanded. As a multi-hop, infrastructureless and self-organized network, Ad Hoc network becomes more and more important. Because it doesn't rely on any pre-established infrastructure and can therefore be deployed rapidly, Ad Hoc network is quite suitable to be used in some special situations such as battlefield, disaster rescue, mobile conference, personal communication, etc. The research of Ad Hoc mainly focuses on the field of media access control, routing, multicast routing, power control, quality of service, security and transport layer. Among these, multicast routing is one of the key technologies.Multicast is one method of transmitting data packets to a group of nodes identified by a single destination address and hence is intended for group-oriented computing. Saving bandwidth and minimizing the payload of forwarding packets are outstanding characteristics of multicast. This point is valuable for Ad Hoc network, because the bandwidth and system resource are limited in Ad Hoc network.One of the multicast routing protocols for Ad Hoc network, that is to say MAODV, is the key work of this paper. Firstly, AODV is introduced by reason that MAODV is implemented on the base of AODV, including routing establishment and routing maintenance. Then this paper leads in some kinds of multicast routing protocols, and analyzes the routing principle, frame message and routing maintenance of MAODV (Multicast Ad Hoc Distance Vector) in detail. Thirdly, after confirming the function of MAODV agent, expanding four main control message and designing unicast routing table and multicast routing table, this paper realizes the simulation of MAODV. Moreover, this paper introduces one kind of link prediction scheme based on location information provided by GPS(Global Position System),and brings forward one kind of improved protocol, that's to say MAODV-RP(MAODV with Relative System). For this protocol, the distance between one node and its neighbor, which is in the same active route, has been calculated to decide whether the neighbor node is out of scope. If so, the protocol will launch new routing discovery in advance. This can decrease the impact of packet transmit ratio and transmission latency brought by link breakage. The protocol also introduces link initiative repair, which can reduce the latency of rerouting. Finally, this paper compares MAODV and MAODV-RP from the standpoint of packet ratio, p2p delay and network overload, and then concludes that MAODV-RP has better performance than MAODV.