Research On Location-aided Routing Protocols In Ad Hoc Networks

A mobile Ad Hoc network is formed by a collection of mobile nodes and it does not rely on fixed based stations or a wired backbone infrastructure. It comes to being solely by interactions among their constituent wireless mobile nodes. The Ad Hoc network offers unique benefits and versatility for certain environments and certain applications.But numerous challenges must be overcome to realize the practical benefits of Ad Hoc network. These include effective routing, medium access QoS issues, mobility management, power management and security etc. Among those challenges above, routing schemes are the mostly focused area in Ad Hoc network.The existing routing protocols for Ad Hoc network mostly are based on the network topology. However, in the randomly changing topology of mobile Ad Hoc network, these routing protocols do not have a good performance. But the geographical location based routing protocol is a new routing design strategy for mobile Ad Hoc network. It takes use of the geographical location information of mobile nodes to choose route.In general, geographical location based routing protocols for Ad Hoc network can achieve the following desirable properties: bandwidth efficiency, power saving, less control message and carrying only location information and identifier of mobile nodes. The transmitting power of mobile nodes can be estimated since the distance between any two mobile nodes is known. Additionally, in any new route discovery, the intermediate mobile nodes need not receive and forward routing packets. It is inherently loop-free, since each data message propagates away from its source. It is robust, meaning that the data message can reach its intended destination by following possibly independent routes. It is adaptive to mobility, since the frequency with which the location information is disseminated depends on the mobility rate.The traditional location-based algorithms that assume the position of destination is reasonably accurate are not able to deal with eventual position deviation and impose high mobility tracking overhead. Moreover, once source node is ignorant of position of destination node, flooding scheme is used instead, which increases control overhead. A novel routing scheme named Location Aided Adaptive Ad Hoc Routing (LAAAR) is proposed in this paper, which adopts hierarchical architecture to achieve a network-wide consistent location database to eliminate inaccuracy that may be introduced by distributed prediction mechanism and implements adaptive adjustment mechanism to combine node movement with route discovery, which can dynamically track mobility of destination node. Control overhead thus can be reduced and destination location information is guaranteed to be up-to-date and accurate enough to enhance the possibility of finding a feasible route. Simulation performed demonstrates that our LAAAR scheme outperforms LAR over a large density of nodes.