The Improvement AODV Routing Protocol Based On Network Connectivity In VANET

Vehicular Ad Hoc Network (VANET) is an application of Mobile Ad Hoc Network (MANET) network in Intelligent Transportation System used in the vehicle tracking, vehicle navigation, traffic detection, traffic safety and so on. Because VANET has the characteristic of network topology frequent changes, vehicle nodes fast moving, bar-type of topology, the existing routing protocol cannot fully adapt to the efficient and stability of data transmission of VANET. Routing protocol is an important part of VANET. So to study the routing protocol to adapt to the VANET network has the important theoretical and practical significance.AODV protocol is a traditional on-demand routing protocol and has good comprehensive performance. When the VANET network has large vehicle nodes and the network of road is complicated, AODV protocol routing exists some problems, such as large routing overhead, long delay of data transmission, poor network connectivity and so on. The improvement AODV Protocol based on Connectivity is proposed to resolve these problems. This article analyzes the influence of road traffic parameters on connectivity and selects road length, number of vehicles and the average speed of vehicles as the impact parameters, and uses the weighted least squares hypersurface data fitting method to establish the connectivity model of road network. To find out the biggest connected probability roads between source and destination vehicle node, the connectivity prediction model and Dijkstra algorithm are used so that restrict the area of AODV radio. The major jobs of this paper are the following:(1) On the basis of VanetMobiSim/NS2, this paper designs the road traffic movement topology and the network simulation of AODV routing protocol. Change the road length, vehicle numbers, average speed of vehicles, vehicle density and the number of lanes respectively, this paper analyzes the influence of different road traffic parameters on connectivity and finds out the main influence parameters.(2) On the basis of the weighted least squares hypersurface data fitting method, this paper finds out the relationships between the traffic parameters and connectivity of road network and establishes the connectivity model of road network. The results show that this model can accurately estimate the connecting probability of road network.(3) Based on the connectivity model of road network calculation the road connected probability between source node and destination node, this paper chooses the biggest product of connected probability of road network by Dijkstra algorithm, and restricts the radio area of AODV. Then this paper proposes an improved AODV protocol by adding the location information of network node to RREQ, RREP and routing table.(4) By use of VanetMobiSim/NS2 simulation platform, this paper contrasts the improvement AODV routing protocol and traditional AODV routing protocol. The results show that the performance of improvement AODV is better in packet delivery ratio, normalized overhead and data transmission delay.