Aodv Routing Protocol Improvement Of Local Repair Mechanisms

With the development of science and technology, portable computer and palmtop computer are increasingly prevalent, and the wireless communication technology develops promptly. In some cases, for instance, the rapid expansion of the army in a war, the rescue after earthquake or flood, it needs one communication technology that needn't depend on any network facility erected beforehand. Then AdHoc network emerge as times require.AdHoc network is one special kind of mobile networks that don't need fixed basestation. It's a self-creation, self-organization and self-supervisory network that formed by the cooperation of a boodle of autonomic wireless nodes or terminals with wireless R-T units.In AdHoc network, every host must be a router at the same time. And nodes in the network could move discretionarily, which make the topology change frequently and the routing protocol be expected to reconstructing and maintaining routing path in time. Because of the highly dynamic variation of topology in AdHoc network, the conventional distance vector routing protocols and link status routing protocols are not suitable.But because of transmission characteristics of wireless channel, and uncertainty of node position, network topo structure is in unstable status, so traditional route ptotocols can not be fit for the characteristics of mobile AdHoc network. Existing AdHoc network protocols also have their limits, and are still in research. So how to modify existing toute protocols in order to improve the robustness, so that the network can be more stable and reliable under bad circumstances. Improving the network service is the purpose of this paper.The thesis firstly described the significance and it's target, it also described the current status of the schedule. And then through analyzing and comparing many routing protocols of AdHoc Network, an optimized protocol ALRDN is presented which is preformed by AODV routing protocol.Route table in ALRDN is extended by adding a field to save the next two hop. And then, according to the discovery packets, marked down the next two hop of the reverse route. When link break occurred, the precious hop of the broken link would broadcast RREQ packets to find its next two hop of that route. If was failed, it would find the proper hop which had enough neighbors from certain area upriver, and then initiate local repair at the hop we just found.Simulation with different scenes is completed based on NS2, the popular simulated formwork, and performance of ALRDN is analyzed according the data obtained by simulation to show that it is superior to the AODV.