A Research On Vehicular Ad Hoc Networks Routing Protocol Algorithms

With the rapid development on ITS(Intelligent Transportation System), VANET (Vehicular Ad hoc Networks) becomes a research hot topic around world. VANET is a kind of wireless Ad hoc network structure for Vehicular communication. It provides Inter-vehicular communication service, Internet Access service, Traffic information acquisition service, and traffic accident early warning service for vehicles. With the application of VANET, it could decrease the probability of emerging traffic accident, and raise the capacity of urban transportation. Compared with traditional Mobile Ad hoc network (MANET), VANET has some characteristics such as the rapid change of topology, complicated communication environment and regular motion of vehicles. From the point of network structure, VANET is a hybrid network structure by式uip infrastructure RSU (Road Side Unit) in the network. As the points above, the routing protocols from MANET work badly in VANET. In recent years, there are many routing protocol algorithms aimed at VANET published by researchers all over the world. In this paper, we analyze the protocol proposed by other authors and propose a new routing protocol by the assistance of RSU base stations. The simple description about the work is as follows:Aiming at complicated urban environment, we assume each intersection is armed with a RSU base station. The RSUs could collect vehicular geographic information. All RSUs are connected with a Location Servicer by wire. The Location Servicer records each vehicle’s position information which includes the street, prediction position of vehicle. By using Location Servicer to provide routing path to vehicles, the network load could be decreased drastically, and an accurate routing path could be selected for delivering data packets.On the basic of RSUs and location servicer, A routing algorithm based on geographic forwarding is proposed. With the help of RSUs, the algorithm could get a well packet delivery ration. In order to avoid the impact from HELLO beacon generated by greedy forwarding, a time-contention based decentralized algorithm is proposed for geographic greedy forwarding under Nakagami propagation model. At the end of the paper, we use NS2to simulate and verify the algorithm. As a result, it shows a better performance than existing routing algorithms.