Research On Routing Algorithms In Vehicular Ad Hoc Network

As an important part of intelligent transportation system, Vehicular Ad hoc Network(VANET) can be applied to solve the traffic congestion and safety problems in cities, whichhas a very broad application prospects. VANET has some characteristics, such as vehiclenode moves at a rapid speed, network topology changes frequently et al. As a result, the linkbetween vehicle nodes break down frequently and the network performance are severely poor.In order to ensure the reliability and stability of the network connection, routing protocolsbecome a key factor to affect the network performance of VANET. Therefore, considering thecharacteristics of VANET and designing a suitable routing protocol has become an importantdirection in theoretical research and practical application.In this thesis, MOVE and SUMO are used to build vehicle mobility model under urbanroad environment, on the basis of that, NS2network simulation platform is applied tocomparatively study AODV, DSR and DSDV protocols. Pacekt delivery ratio, normalizedrouting load and average end-to-end delay under different vehicle velocities, number ofvehicles and packet sizes are analysed to evaluate the routing performace of those threetypical MANET routing protocols. Simualtion results demonstrate that the overall routingperformance of AODV protocol is better than DSR and DSDV protocols, but it is still notgood enough to be adopted in VANET.On the basis of AODV protocol, by introducing priority nodes judging mechanism androuting backup mechanism, this thesis proposes a new improved routing protocol calledVSRP (Stable Routing Protocol for VANET). VSRP uses two new mechanisms as follows:the priotity nodes judging mechanism is used in routing discovery phase to limit the numberof forwarding RREQ messages and prevent the flooding caused by broadcasting RREQmessages; the routing backup mechanism is used in routing maintenance phase to improve theefficiency of routing repair and shorten the routing recovery time. This thesis respectivelysimulates AODV and VSRP protocol under urban road environment through NS2networksimulation platform. The simulation results indicate that, compared with AODV protocol,VSRP protocol can increase packet delivery ratio, reduce routing overhead and shortenrouting recovery time. To sum up, VSRP protocol improves the overall routing performanceand it is more suitable for VANET.