Research On Reliable Data Distribution Strategy In Vehicular Ad-hoc Network

With the development of vehicle technology and the popularity of vehicles, vehicle has become an indispensable part of our life. In order to achieve safe driving and improve traffic efficiency, VANET (Vehicular Ad hoc Network), as a new research field of wireless communications, has become an important component in ITS (Intelligent Transportation System). Most of the studies have been carried out for compact vehicular network, but few attentions have been paid on data distribution in sparse network such as rural or highway, this paper aims at the research on data distribution strategy in sparse network.Firstly, the concept and the situation of study of VANET are introduced, and based on the introduction, the characteristics of the vehicular network are analyzed, and also the architecture of VANET protocol is studied hierarchically, especially the data distribution protocols in the network layer are analyzed and compared.Secondly, the characteristics of sparse VANET are summarized, and the difference between compact and sparse VANET are proposed, the challenges brought by the special characteristics to the data distribution strategy are analyzed, and the strategies to deal with the challenges are put forward.Finally, a new data distribution protocol EPF (Enhanced Perimeter Forward Protocol) is proposed in vehicular network, based on the combination of greedy algorithm and node mobility, the protocol puts forward the role-based data distribution method. The role is designed by the position and direction of vehicle node, and different role will adopt different data distribution method. For improving the reliability, the protocol model proposes the way to overcome the black hole and network fragment, and the synthesization of the characteristics of position-based and role-based is put forward to gain better adaptability to the network fragment and topology change brought by high speed movement of node in sparse VANET, so the protocol model can satisfy the demand of safety application. The EPF protocol model simulation is carried out under NS-2 network simulation platform, the simulation results prove that the role-based data distribution strategy can achieve the real-time data distribution in sparse network,the strategies in EPF protocol model to overcome the black hole and network fragment can better meet the reliability requirements in sparse network.