Research On Routing Algorithm In Sparse VANET

As an important technology for ITS (Intelligent Transportation System), VANET (Vehicular Ad-hoc Network) is playing an important role in the modern logistics transport. Especially in the area where communication infrastructure construction is weak, VANET provides an effective mean to announce vehicle information, road information, warning information, etc. Various traditional VANET routing protocols have been proposed for wireless networks with dense distribution of wireless nodes. However, it’s difficult to get better tradeoff between message transmission delay and communication overhead in DTN (Delay Tolerant Network), where the wireless network is sparse.Based on the typical characteristics of DTN, two routing algorithms are proposed for the sparse VANET in this paper. Paper reviews the DTN research background, typical applications, research status, and then analyses the BSW (Binary Spray and Wait) routing algorithm. BSW set a number L of copies of the message at source nodes. Then it generates L copies of task of transmitting information with the method of Binary-Tree in spray stage, and forwards to destination nodes in wait stage. Limited number of copies, BSW reduces communication overhead and competition conflicts. However, the number of copies is difficult to determine, and spreading of news is blind that may cause unnecessary network costs and transmission delay in spray stage. In order to solve the problems of sparse VANET, a data dissemination algorithm is proposed to distribute data to the same or reversed traffic based on message properties. According to the message properties and number of the nodes, the proposed algorithm computes the number of copies of the message, and then forwards task of the message copies to the node based on the method of Binary Tree. Simulation results show that the proposed routing algorithm can achieve higher rate of message delivering than the relative existing algorithm, and reduce communication cost significantly, which proves that it is feasible and practical.Then a novel message routing algorithm SSR (Sequence of Street based Routing Algorithm in Sparse VANET) is proposed, which combines inter-vehicular communication with store-carry-forward method in a multi-hop network. It is assumed that a GPS satellite navigation system is mounted on each vehicle and the vehicles in network are sparsely distributed. A multi-hop routing is specified not by a sequence of IDs of intermediate nodes but by a sequence of street crossings. Since the locations of street crossings are stable, higher reachability of messages is expected. This paper uses ONE (Opportunistic Network Environment simulator) simulation tool as an experimental platform. By setting up different simulation scenes for the proposed routing algorithms, the performance of the algorithms is verified. Experimental results show that the proposed two different algorithms have good performance and are suitable for the sparse network environment.A vehicle terminal system is designed and implemented. The telematics system supplies drivers and passengers with various information and service, such as real-time vehicle GIS information, status information, video information, fuel consumption information, stow materials information, multimedia and Internet access, etc. Based on the embedded system with ARM9, terminal system has GPS module, CDMA module, USB camera, etc. This chapter describes the detailed hardware structure and system functions. Terminal system is a feasible scheme to verify the reliability and practical of the VANET routing algorithm.