Research And Improvement AODV Protocol Of Ad Hoc Network

Mobile Ad Hoc network is a group of mobile nodes with wireless transmitters andreceivers,forming a multi-hop temporary self-organized network.It does not require any fixedinfrastructure support.It can be widely used army,rescue,terrible environment and poortransport facilities places. Nodes in the network can freely enter or exit the network, any nodedoes not affect the operation of the entire network Due to the characteristics of dynamictopology of Ad Hoc Networks, leading to the traditional routing protocols cannot be applied.How to provide a stable and efficient routing for Ad Hoc network has become an importantresearch. AODV is a on-demand routing protocols.That is to say,AODV only need searchrouting when nodes have message to send.So it need not broadcast message to maintancerouting information between nodes. However,AODV exposure many defects with researchdeeply.Such as long delay,excessive consumption a node’s energy,cannot select routingdymaicly and broadcast storm.In order to adjust Ad Hoc network better, it is necessary toimpove AODV protocol.This paper first introduces the development of Ad Hoc networks,as well as the researchin the field.Then introduces the characteristics of Ad Hoc network from application anddevelopment prospects.Then describes routing protocols in Ad Hoc networks with differentcategories.And make compare about routing protocols.This paper also raise some index toweight network capability.It also analysis the process of AODV routing protocol and putimpoving methods about AODV protocol. At last,this paper raise two impove methods:baseon probability and clusterhead.1:When AODV first receive RREQ,it will forward unconditional.This method can findright routing as soon as possible,but it will cause broadcast storm and increase networkoverhead. Forwading a RREQ packet can only increase effective broadcast area61%throughresearch.So,we can discard some RREQ packet.Because it is not effect routing search,but candecrease broadcast storm.This method compute node’s neighbor numbers.Different nodes usedifferent forwarding probability.This improving method can decrease broadcast storm anddelay through NS2simulation test.2:When AODV find a right routing,it will not search another routing unless link is break.However,the network toplogy would change with nodes move.So the better routing willappear. It may make some nodes die to soon,so it will decrease network’s lifetime.This paperraise clusterhead select algorithm base on energy.This algorithm select those node where itdump energy is largest in neighbor list.A energy threshold is define in order to prevent somenodes energy excessive consumption. Every clusterhead can manage amount of nodes.Thearea data transmit are through the clusterhead.Through running clusterhead maintenancealgorithm can avoid clusterhead energy excessive consumption. Trandition clusterhead selectalgorithm need GPS,but the impoving algorithm needn’t.This method can decrease node’sdeath rate,extend network lifetime through NS2simutation test.