Adhoc Network, The Aodv Routing Algorithm And Optimized

A mobile Ad hoc network is an autonomous system of mobile hosts connected by wireless links. Such networks are useful in military and other tactical applications, e.g, army's quick spread and advance in the battlefield, emergency rescue or exploration missions after earthquake and flood, where cellular infrastructure is unavailable or unusable. In such a network, each mobile node operates not only as a host but also as a router. This network has a series of the strengths, for example,MANET can be built rapidly and easily, and it is not restrained by wired network, and so on.Because of constantly changing topology, Ad hoc networks can't adopt traditional routing protocols. Research of routing protocols becomes the most important part of the research of Ad hoc. The actuality and prospect of Ad hoc networks are summarized in chapter one of this paper, including the definition, characteristic, application fields and critical technologies of Ad hoc networks. Then based on Ad hoc networks, this paper gives a particular analysis of AODV routing protocol,and compares some relevant network protocols with AODV such as DSDV, DSR. AODV ,as the synthesis of DSDV and DSR, depends on middle nodes to establish and maintain route table, uses sequence number to avoid the appearance of route circle, supports the function of group broadcast and QOS, uses IP address, depends on the network link and dosen't support single orientation channel. Furthermore, this paper analyses the capability of AODV routing protocol by testing end-to-end average delay, data package transmission ratio and route cost in different network environment with NS-2, and draws a conclusion that AODV routing protocol has a bigger route cost. There is an obvious increase in route cost with the expansion of the network overload.Thus this paper makes some improvements in the aspect of route cost. These improvements are proved, by a series of tests in the final part of the paper, to be more effective in route cost.The comparison between protocols and improvements of AODV protocol are based on NS-2 network simulation environment, the platform of this paper is Windows 2000 and Cygwin, and this paper provides reference methods, reference model and reference data for the design and programming of practical system.