Study On Routing Protocol For Urban VANETs

With the development of intelligent transportation system, VANETs have become a concentrated research area. VANETs are mainly used in assisting safe driving, improving traffic efficiency and providing in-car entertainment or Internet access services.As the key component of VANETs, routing protocol largely determines the overall performance of VANETs. Because the rapidly moving of vehicle node leads to the frequent changes of the network topology and the unstable quality of wireless link, routing protocol research for vehicular ad hoc networks is a challenging job. The routing protocol based on topology cannot adapt to the high dynamic environment, and its performance is very poor in VANETs. The routing protocol based on geographic location information does not need to maintain a fixed route, so it is strongly expansible and more suitable for high-speed mobile scenarios. Compared to the highway environment, the urban environment is characterized by more vehicles, road complex and more data transmission demands. So the routing protocol for urban VANETs is a hot research topic.In this thesis, we study the routing protocol based on location information for urban VANETs. On the basis of analyzing some of problems faced by urban VANETs routing protocol, a hybrid information and redundant transmission based routing protocol for VANETs is proposed. The protocol is divided into two parts, which are reliable transmission within road section and road section selection. According to urban environment characteristics of the road, an undirected graph is abstracted, where the intersections are vertices and road sections are edges. The stationary nodes deployed in the intersection can collect information of the traffic density and the network delay, and give a weight value for each edge base on the integration value of them, and then use the Dijkstra algorithm to calculate the shortest path between any two intersections. It is about road section selection. As for the data transmission within road section, the next node is selected by considering the distance, speed and link reliability, and the success rate of data transmission is improved through redundant transmission technology. The simulation results indicate that the proposed routing protocol performs well.