The Simulation And Analysis Of Local Recovery Mechanism In AODV

Ad Hoc networks composed of mobile nodes with wireless communication device are typically characterized by their multi-hop, temporary and un-center, wireless Ad Hoc network being a new multi-hops and self-organized network is becoming the research focus. And the network's flexible features bring the new challenge on networking. With the nodes in Ad Hoc networks moving fast, the topologies of Ad Hoc networks are constantly changing. The traditional routing protocols used in Internet can not adapt to the need of Ad Hoc networks. Adaptive routing algorithms must be designed to solve the routing question in Ad Hoc networks. The researched on the routing protocols are important research issues of Ad Hoc networks.Firstly, this paper introduces the concept and characteristic of Ad Hoc networks. Then it introduces of one kind table driven protocols DSDV, three kinds of on demand protocols AODV, DSR, LAR, and one kind hierarchical protocol ZRP. Finally the common routes of Ad hoc network are compared.DSR respond all route request information, therefore source nodes can obtain more route information about destination node of reserved routes. AODV only reply the first route request information, so the route table only has one route which can reach the destination. When this route becomes invalid and other inter-node also does not have the route of destination, a new RREQ information has to broadcast to find a new route. Source AODV protocol has improved this process through local repair. This paper proposed some kinds of new method based on local repair mechanism. The nodes of invalid route can immediately execute local repair process regardless of their position on the route. Simulation shows improved algorithm advanced network performance.AODV protocol can only obtain limit route information because it isn't based on the use of the technique "routing source" and absence of hybrid monitor mode, so a node has to broadcasts a RREQ when it needs a route of the destination,though this process can increase network burden. Source algorithm has taken some measures to limit the flood of RREQ by confining the hops of node and prohibiting the node to broadcasting the same information. This paper can limit the scope of RREQ further by choosing the node which has less local topology changes to broadcast RREQ, the proposed two kinds of local repair method also applied to route repair method .The above change has been applied a modified algorithm for selecting path and local recovery of AODV. The result show improved algorithm has some superiority.