Research Of Map-Based Multi-Path Routing In Vehicular Ad Hoc Network

Vehicular Ad Hoc Network (VANET) is a special wireless self-organized network that is applied to inter-vehicle communication, as an important part of the Intelligent Transportation System (ITS), VANET has become a popular network communication technology in recent years and has huge development potential. Through VANET, drivers can obtain the real-time traffic information and the neighboring vehicles information, it can effectively reduce the occurrence of traffic accidents and improve the traffic conditions. The access of LAN and Internet can provide the drivers with entertainment and leisure, make the driving more convenient. In VANET, the fast moving of vehicles makes the network topology change frequently, the unreliability of wireless channels and the uneven vehicle density, which make the routing break frequently. The traditional Ad-Hoc routing protocol is no longer suitable for the VANET. We need to design a routing protocol for the VANET which is reliable, real-time and robust.In this paper, we analyze the shortcomings of the existing routing protocols under the urban scene firstly, then propose a new kind of routing protocol which is called MBMPR(Map-Based Multi-Path Routing). In MBMPR, we use the GPS, vehicular sensors and electronic map to make routing decisions, calculate an optimal forwarding path and one second optimal backup path by using Dijkstra Algorithm. The algorithm not only considers the length of every road, but also takes the vehicle density into account, which will reduce the probability of the local optimum problem caused by the sparse connectivity. A congestion detection mechanism is proposed to solve the load balancing problem in the intersection. When the packets cannot be successfully deliver to the target vehicles because of its movement, a repair strategy which combines the location service and mobility prediction is introduced to improve the packet delivery ratio.Finally, the movement model of urban scene is generated by SUMO(Simulation of Urban MObility) and simulations are conducted by NS2. The results show that MBMPR protocol provides higher packet delivery ratio and lower latency. Therefore, the MBMPR is more suitable for the high density, fast moving and high load VANET under the urban scene when compared with other protocols.