Research On Position-based Route Protocol For Vehicular Ad Hoc Network

Vehicular Ad hoc network (VANET), as one of the basis of intelligent transport systems, provides a mobile communication platform for vehiculars to improve traffic efficiency, reduce traffic accidents and make users access Internet more conveniently and rapidly. Each vehicular with function of terminal and router, discovers and maintains route to other nodes in VANET. Traditional routing protocols for mobile Ad hoc networks are not fit for VANET, as it needs to consume a lot of the available bandwidth for maintaining unused paths, and VANET has its own features such as the limited bandwidth, the frequently changing topology, the link that is easy interfered and limited transmission range etc. As a consequence, designing a rapid and efficient routing protocol is one of main study on VANET.Position routing protocol, which routing decision need not to establish and maintain routing table, uses geography position to achieve small per-node routing state, small routing protocol message complexity and extremely robust packet delivery on densely deployed wireless networks, is well used in such scenario as network with many nodes and topology change frequently. It mainly includes packet forwarding strategy and location service. Location service for Ad hoc networks is used to locate the geographic position of a given node in the network. One of the main usages of location services is in position-based routing algorithms. In particular, position routing protocols can route packets more efficiently to their destinations based on the destination node's geographical position provided by location service.In this paper, position-based routing protocols for VANET and location service mechanism are researched and analyzed, the existing problems of using location service designed for mobile Ad hoc networks in VANET have been found out, and the relative solution is proposed in this paper. The main research content in this paper is focusing on five parts as follows:Firstly, we expatiate the significance and background of researching inter-vehicle communication and its relatives, give an analysis to the current trends, challenge and the development in this area, survey some of the recent research results on routing protocols for vehicular networks, analyze some of the researching challenges that still need to be addressed referred to position-based routing protocol and location service mechanism for VANET. Secondly, we analyze and compare the performance on topology-based routing protocols (AODV and DSR) and position-based routing protocol (GPSR) by providing a simulation for mobile Ad hoc networks. Simulation results indicate, compared with DSR and AODV, stateless protocol GPSR greatly enhances the throughput and decreases the loss rate and the transmitting delay of packets.Thirdly, we propose a novel location service mechanism for VANET called ILSV (Intersection Location Service for VANET), a distributed location service algorithm that makes use of the features of street intersections and traffic rules such as driven-slowly vehicular and many stopped vehicular. The basic idea of ILSV is that nodes in the network update its position to the location server located in intersection. When location server is out of intersection, it broadcasts its vehicular node location information table to the other location server located in the same intersection as it. Each intersection selects a location server with maximum location information capacity to exchange vehicular node location information table when timer expired.Fourthly, we design and implement the location service mechanism under network simulation platform NS-2 which is integrated into position based routing protocols such as stateless routing GPSR and demonstrate these traits and its performance by providing an extensive simulation in a wide of urban scenario. Compared with existing location services GLS (Grid Location Service) and HLS (Hierarchical Location Service), ILSV achieves good results in terms of query success ratio, query delay and remarkable scalability with respect to network size.Finally, we take a secondary development on traffic simulator platform SUMO to generate traffic simulation scenario files for urban VANET simulation.