Improvement On AODV Routing Protocol Of Ad Hoc Network

Ad hoc network is an autonomous system which is temporary, no center and multiple hops, consisting of a set of nodes with wireless transceiver equipments. Because the network does not need communication infrastructure and networking is simple and convenient, so it is widely used in geological exploration, environmental monitoring, emergency communication and military fields.In Ad hoc network researches mainly focus on network security, energy of node saving, quality guarantees and routing protocols, etc. AODV (Ad hoc On-demand Distance Vector) is a kind of on-demand routing, which is a comprehensive protocol based on table-driven routing DSDV (Destination-Sequenced Distance-Vector Routing) and on-demand routing DSR (Dynamic Source Routing). On-demand thought and jump forward mechanism of AODV can significantly reduce routing overhead, so AODV is strongly adapt to the Ad hoc network.For lacks of AODV routing protocol exists, the paper proposes the following two aspects of the improvements:(1) For AODV route discovery phase easily leading to issues such as broadcast storms, this article proposes a regional probability forwarding mechanism in which the routing request packets received are forwarded by the corresponding probability calculated by the number of the neighbor nodes, in order to ensure the stability of the links, introduce energy factor when the routes established,(2) Aiming at problems in link maintenance phase of AODV such as time delay, link prediction repair mechanism is proposed, which predict links by the a variety of factors affecting the link stability and trigger link repair when the predictive value below warning level,(3) For these two improvements, modify the codes in the NS2(Network Simulator, version2), compile the improved algorithm into NS2, construct the corresponding simulation scenarios, and then obtain the simulation data. Through the analysis of simulation results, show that the proposed two algorithms made up for the inadequacy of AODV, improve the efficiency of the routing.In this paper, do a lot of comparative experiments between AODV and improved AODV by NS2, and the experimental comparison results mainly reflected in the getRatio(packet delivery ratio), average delay(average transmission delay) and load(normalized routing overhead), which are the indicators that can reflect the routing performance. The simulation results show that the improved AODV routing protocol can reduce the network delay and routing overhead, to a certain extent, improve the packet delivery rate, and verify the effectiveness of the improved algorithm.