Study Of Routing Algorithm In Vehicular Ad Hoc Networks

VANET (Vehicular Ad Hoc Networks), which is composed of cars equipped with a wireless network interface devices, is a special MANET (Mobile Ad hoc Networks) with multi-hops. It is currently one of the transportation domains with most future prospects. The routing protocol has decided the entire network performance to a great extent. In VANET, because the node's rapid traverse results in a dynamical change of the network topology, and the node migration is limited by the path model's characteristics, it can't use directly the existing MANET routing protocols. Therefore, how to design the routing protocol to safeguard the information transmission rapidly and reliably, has been the hot and the difficult problem of VANET. Since the position-based routing protocol has the strong compatibility on the frequently changed network topology, it is suitable for VANET. In this paper, based on the OPNET network simulation platform, we study the location based routing protocols of VANET and develop the OPNET modules of GPSR protocols, which is a classic position based routing protocols, and described an improved GPSR-EZ protocol.We first introduce the origin, characteristics, and applications of the VANET, and then summarize and conclude the classic routing protocols presented in previous literature. Secondly, by OPNET platform, we study position based routing protocols in VANET and develop the OPNET model of GPSR protocol. Then we describe an improvement for the classic GPSR protocol, called GPSR-EZ, and establish the GPSR-EZ model of OPNET. Compared with the GPSR protocol, GPSR-EZ can improve the packets delivery ratio, reduce the total dropped packets under random mobility environment. Node movement model, as a result of the impact to simulation, is an important factor. Node movement model used in VANET simulation should be able to reflect the actual movement of vehicles. Based on the analysis of the characteristics of vehicle movement model, we use the traffic simulation software which can describes the trajectories of motor vehicles more truly, and study how to use traffic simulation platform VanetMobiSim. Finally, we combine the VanetMobiSim traffic simulation, OPNET simulation for GPSR and GPSR-EZ to compare and analyze their performances under specific highway environment.