Map-based Routing Protocols For VANET

With the improvement of people’s living standard, more and more vehicles are on the road,vehicle need more and more applications to meet the needs of drivers such as advanced parking, road congestion detection, the slippery road warning and so on.In the city environment, serious network segmentation and inhomogeneous density distribution result in reduced performance of vanet routing protocols.The research object of most of routing protocol is mainly static nodes, but in vanet, high speed mobility of vehicles result in topology changing very frequently, so designing a routing protocol becomes particularly important to meet communication requirement of mobile vehicles.According to the above situation, this article has proposed a routing protocol that called DMBA in vanet that based on map navigation. In routing algorithm, each road statistical traffic density independently, when traveling into a specified section, vehicle adjust message forwarding strategy according to real-time road traffic density.The main research results are as follows:(1)In the process of vehicle communication, the road traffic density is the key factor to determine the packet forwarding strategies, this paper presents a method of statisticling road traffic density that vehicle in the road broadcast their speed and other information to other vehicle in the same road vehicles periodically, when the vehicle traveling into this road, vehicles can obtain real-time density to determine the corresponding forwarding strategy.(2)Vehicle is moving fast, but the vehicle is limited by road, so the location of the vehicle is predictable.In the process of data transmission,predicting the location of the destination node can increase the success rate of data transmission. This paper proposes a kind of prediction method of vehicle location which is based on cellular automata, the vehicle can predict the position of the current node in different time according to the neighbor nodes, then it can predict the trajectory curve of vehicle using the method of linear regression.(3)This article has proposed a routing protocol that adjusting message forwarding strategy on the basis of traffic density. When vehicle density is high, the data transmission adopt fast forward to ensure the small end-to-end delay.When road density is low, the intermediate node select next node considering the similarity of the motion path of neighbor node and transmission path of packet.If no suitable nodes in the surrounding is selected as next node, Vehicle predicting minimum distance and the shortest time delay of neighbor node and destination node in the future time to determine whether a message is carried or forward by the current node.(4)In this paper, simulate DMBA and GPSR, and analyze the performance of the two routing protocol using NS3.DMBA has outperformed GPSR with higher delivery ratio and end-to-end delay.