VANET Networking And Related Technology Research Under Urban Traffic Environment

Cars have become the main transporter for people. They provide people with convenient transportation, however, they bring some problems such as road congestion, traffic accidents and so on. Intelligent transportation system (ITS) has become the trend of traffic in the future. VANET is a kind of Ad Hoc, which can exchange speed, location and other information between vehicles within a certain range of communication. Vehicles can obtain real-time information about road condition, which can assist driver to make correct and timely decision to avoid traffic accidents and improve safety through VANET. VANET is the basis of ITS. And it has features of high speed, network topology changing frequently and so on. The related technology of VANET has attracted a lot of attention in academia around the world.The relevant technology of VANET has been studied under urban traffic environment in this thesis, focusing on VANET networking and connectivity technology.In terms of networking, after analyzing the plane structure and cluster structure, the thesis investigates a kind of networking strategy based on clustering structure. Furthermore, this thesis puts forward a scheme which uses a bus as the cluster head, because of buses’easy-management and fixed route, and focus on solving cluster head election and dynamic management of cluster members in this scheme.In order to solve communication interruption caused by vehicle sparse, the thesis discusses the idea of roadside parked vehicle caching and forwarding and tolerate delay. According to connectivity interruption caused by communication congestion which is divided to intra-cluster and inter-cluster congestion, the thesis proposes the schemes prospectively. For the intra-cluster congestion, the thesis presents a strategy which extends heartbeat message releasing cycle to reduce the communication pressure. For inter-cluster congestion, the high priority message can be transferred preferentially through adjusting forwarding path of the lower priority message.Finally, simulation results show that it extends communication time effectively and improves transmission efficiency.