Research On Routing Optimization Scheme For Vehicular Ad Hoc Networks In Urban Scene

Recently,as more and more people are familiar with terms such as driverless vehicles and autopilot,building a mature and sophisticated Intelligent Transportation System(ITS)has gradually become a hot research topic in the academic and business world.Vehicular Ad Hoc Networks(VANETs),as an important wireless network communication technology in intelligent transportation systems,have broad prospects for development.Compared with other forms of networks,vehicular networks require higher real-time and accuracy of communication information and it is necessary to design a routing protocol that is suitable for urban scenarios.This thesis focuses on analyzing the shortcomings of position-based routing protocols and map-based routing protocols in urban scenarios.then discusses the characteristics of vehicle flows and road distribution in urban scenarios,and designs global role nodes and local routing table routing protocol(GRLTR)that is suitable for urban scenarios.Considering that map-based routing protocols lack considerations on the problem of different density of vehicles nodes in different areas of the road,GRLTR protocol plans routing lines according to the global road state and simplifies routing lines by setting role nodes to avoid routing hollow caused by data packets traveling along sparsely populated roads.For the problem that location-based routing protocols need to calculate a large number of inter-node distances in the transmission process,GRLTR protocol puts forward the idea of storing local routing tables for the first time on the basis of reasonable control of the storage overhead,making multiple data packets destined for the same destination node can be sent directly to effective next hop node without calculation,significantly reducing the end-to-end delay of packet transmission.In addition,considering the real-time requirements for the routing records in the local routing table during the data packet transmission process,the GRLTR protocol also sets the routing table patching mechanism and predicts the location of the destination node at the last hop.Compared with the performance of the classic routing protocol in the vehicle network,the GRLTR protocol effectively reduces the packet loss rate and end-to-end delay,and improves the stability and usage of the routing link.This thesis uses OSM open source map,traffic simulation software SUMO and network simulation software NS2 to form a complete simulation environment to verify the performance of the GRLTR protocol and compare it with the GPSR protocol based on geographic position and the GSR protocol based on map.The experimental results show that GLRTR has lower packet loss rate and end-to-end delay compared with GPSR and GSR in the urban scene with large data traffic volume and uneven vehicle distribution.It can realize highly real-time vehicular network communication.