The Research On Reliable Routing Method For VANET

With the development of communication technology and the increasing number of vehicles on the road,people put forward higher requirements for safe travel.Intelligent transportation system(ITS),as an important part of building a smart city,has become a hot topic in recent years.As the main communication technology of ITS,VANET has the characteristics of frequent network topology change,unreliable communication link and nonuniform distribution of vehicle nodes.These features make the design of high-reliability and low-latency routing algorithms become a challenging task.Effective routing algorithm can not only ensure reliable communication between nodes,more importantly,but it determines the flexibility of application deployment.Therefore,to study the reliable routing algorithm has important significance to realize ITS.In this paper,firstly,the routing related technologies is discussed in VANET.Through the detailed study about communication architecture and routing algorithm in VANET,the factors that affect the routing performance were summarized.Then,the existing routing design method in VANET is discussed in detail,in order to prepare for the following routing design.Secondly,through the detailed study of the relationship between vehicle motion and links,a link maintenance time model is established.Based on this model,it is proved that the link maintenance time between nodes obey log-normal distribution,and the link reliability calculation method is proposed.Q-learning algorithm,as an unsupervised intelligent algorithm,can find the shortest path between the source node and the destination node through multiple iterations.In this paper,we design a reliable self-adaptive routing algorithm RSAR by applying the original Q-learning algorithm to the routing algorithm design.The learning tasks are distributed in every vehicle node in the distributed way.By periodically exchanging information with neighbor nodes,it can effectively solve the unreliable path problem caused by topology changes.Finally,the performance of RSAR algorithm is verified by NS2 network environment.Finally,The clustering algorithm,as a hierarchical architecture,it can effectively improve the performance of routing algorithms.However,the existing clustering algorithms only use the relative mobility as a reference factor to select cluster heads,and does not consider the link reliability between nodes in cluster.The slight change of the cluster head speed has a great influence on the cluster structure,which makes the stability and reliability about cluster is poor.In this paper,a passive multi-hop clustering mechanism(PMC)is proposed.In the initial stage of clustering formation,a priority-based vehicle following strategy is proposed to guarantee the reliability and stability of cluster.In the clustering maintenance stage,a novel cluster merging mechanism is proposed to further improve the stability and scalability.Finally,the PMC algorithm is experimentally verified in the NS2 simulation environment,and compared with other related algorithms.