Research On The Routing Proctocol For Vehicular Ad Hoc Network

VANET is a unique MANET composed of vehicle nodes.Compared with MANET,VANET has the characteristics of frequent changes of the vehicle nodes and the frequent changes of the network topology.The traditional mobile ad hoc network routing protocol does not take into account the characteristics of VANET.How to select the appropriate route in the frequently changing network topology is one of the key technologies of VANET.In this thesis,the protocol of VANET is studied.A cross-layer routing protocol based on forwarding efficiency prediction is proposed under the highway scene.A geographic routing protocol based on road topology and a routing protocol link based on capability prediction are proposed under the urban scene.The concrete contents are as followed:(1)In order to solving the problem that the traditional geo-information-based routing protocol can not effectively consider the position change caused by the high-speed vehicle movement,combining the non-competitive multi-channel MAC protocol a new greedy perimeter stateless routing based on efficiency prediction(GPSR-EP)is proposed.GPSR considers the transmission failure probability of channel fading,and defines the transmission latency in conjunction with VeMAC,which can reflect the queue length and slot occupancy of the node.On this basis the forwarding efficiency of all nodes in the next hop is predicted,and the optimization of transmission distance in the unit time is used as the strategy to improve the channel utilization.The simulation results show that GPSR-EP can improve the efficiency of network transmission in high-speed scene.(2)In order to improve the performance of VANET under the urban scene,taking into account the road topology and geographic location information,an improved geographic routing protocol based on road topology(TGR)is proposed.TGR combined with the non-competitive MAC protocol,the paper analyzes the generation of voids,and gives an effective method of target node selection.In order to solving the problem of low forwarding efficiency in traditional recovery mode,a new recovery mode that relies on junction node characteristics is proposed.The simulation results show that TGR can improve the network performance effectively in the grid city scene.(3)Constructed a scene that reflects the characteristics of urban roads and the mobility of vehicle.Aiming at the problem that AODV protocol can not effectively consider the link stability in the urban scene,a link capability prediction VANET routing protocol(LCPR)is proposed.Based on the non-competitive multi-channel MAC protocol,considering the direct transmission success probability between the nodes,the traffic load of the node and the channel occupancy around the nodes,LCPR defines the communication capability of the nodes,which reflects the efficiency of transmission between nodes.On this basis,a new route for urban scene is proposed using a cross-layer design.Simulation shows that LCPR can significantly improve the network performance such as packet loss rate and end-to-end average delay in urban scene.