Research On Vanet Routing Protocols In Urban Environment

With the continuous development of the vehicle industry,VANET(Vehicular Ad Hoc Networks)has become an important part of intelligent transportation system.VANET mainly has two application scenarios: the urban environment and the highway.The urban environment is much more complex than the highway.VANET routing protocol is one of the key technologies and plays a decisive role in network performance.Therefore,it is very important for smart transportation system to design a well-behaved routing protocol that can be used in urban environment.Firstly,this paper makes a thorough evaluation about GPSR(Greedy Perimeter Stateless Protocol)routing protocol and points out some defects of it.Then,a new forwarding mechanism based on GPSR forwarding mechanism is proposed to select the optimal forwarding node.Then,according to the new improved forwarding mechanism based on greedy forwarding mechanism,this paper introduces a multi-channel data transmission protocol named MP-GPSR(Multipath Greedy Perimeter Stateless Routing)to solve the problem that next hop node will be overwhelming traffic if two packets with same destination address arrive at the same next hop almost in the same time.Furthermore,this paper also presents BR-VANET(VANET Based On BUS and RSU)routing protocol that improved by VANET based on BUS,it integrates vehicles,BUS,RSU(Road Side Unit)and Vehicle Control Center(VCC)to provide better data transmission services.RSU can make up for the limited defects in the coverage area of the trunk transmission due to the limited number of buses.VCC helps to locate the target vehicle quickly.Compared with other improved protocols based on bus,the BR-VANET has better performance,it can improve packet delivery rate and reduce the end-to-end average delay.Finally,this paper adopts a combined simulation platform based on SUMO and NS-3.By conducting a series of simulation experiments,this paper analyses the delivery rate and average end-to-end delay of GPSR,GPCR,ROGRP and MP-GPSR under different simulation scenarios.The results show that,compared with GPSR,GPCR and ROGRP,MP-GPSR improves the delivery rate and shortens the end-to-end delay.Then,by conducting simulations on the introduced BR-VANET,BUS-VANET,MI-VANET,BUS-NET and traditional VANET routing protocols,this paper compares their delivery rate and the average end-to-end delay under different simulation scenarios.Simulation results show that,compared with BUS-VANET,MI-VANET,BUS-NET and traditional VANET routing protocols,BR-VANET improves the delivery ratio and average end-to-end delay.