Research And Improvement Of AODV Protocol In Vehicular Ad Hoc Network Environment

As an important part of intelligent transportation system,Vehicular Ad Hoc Network(VANET)has some characteristics: for instance,vehicle nodes moving rapidly,network topology changing frequently and so on.As a result,the link between vehicle nodes break down frequently and the network performance are severely poor.Therefore,it is very important to design an efficient routing algorithm for VANET networks,which is of great significance for the improvement of urban traffic congestion and safety.In this paper,the characteristics of the VANET and the AODV protocol are analyzed and studied,then an improved protocol,LS_AODV(Improved AODV protocol based on Link Stability)is proposed.The major research work is as follows:(1)We analyze the characteristics and principles of several classic movement models,which are focused on the research of vehicle mobile models for VANET environment.Then we design a vehicle mobile model with lane changing and overtaking function based on urban street topology to make the simulation environment be more consistent with the actual traffic environment.Finally the software VanetMobiSim is used to simulate the vehicle mobile model.(2)AODV routing protocol is simulated and analyzed based on the vehicle mobile model.A co-simulation platform is set up by the Vanet MobiSim2.0 and NS2 in Linux system to realize the VANET network simulation,and three parameters: vehicle speed,number of vehicle and packet delivery are analyzed how to impact the network performance.Simulation results indicate that the increase of vehicle speed,vehicle number and packet sending rate make the network average end-to-end delay and packet loss rate increase,packet delivery rate decreases,which leads to the decreases of the overall network performance.(3)This paper proposes the LS_AODV routing protocol with better performance by analyzing the defects of AODV routing algorithm applied to VANET network.First,in the route discovery phase,the priority node filtering mechanism is introduced to select some nodes with better forwarding performance.Second,in the routing phase,the link effective time-based mechanism is proposed to select the route of the longest effective time from thesource node from the destination node as the main path for data transmission.Last,in the routing maintenance phase,the neighbor node backup mechanism and the effective route backup mechanism are introduced to repair the local routing and the full routing respectively.