Reliability Routing Protocol Based On Dynamic Transmission Range In VANET

In recent years,with the rapid development of economy and technology,people have hig her requirements for traffic quality.Therefore,the Intelligent Transportation System(ITS)has received extensive attention.It improves the safety of the vehicle while driving,the efficiency of the city traffic and the driving experience of the driver.Vehicular Ad-Hoc Networks(VANET)is the foundation of intelligent transportation systems.VANET uses vehicles to vehicles(V2V)communication and vehicles to roadsize(V2R)communication to obtain important information in the transportation network to support various applications.Routing protocol is the main technology of VANET,which can improve the efficiency of communication in VANET.However,VANET has the characteristics of fast moving speed of vehicles,frequent changes in network topology,and complex urban traffic environment.Therefore,designing a routing protocol that conforms to the urban traffic environment has become a key and difficult point in VANET research.In VANET,the density of vehicles on the road is constantly changing and the transmission range is fixed,which brings about a problem of poor network connectivity and high bit error rate.At the same time,the high-speed mobility of the vehicle makes the communication link stability between the vehicles poor,which causes the communication link to be easily broken,the packet loss rate is high,and the communication efficiency is relatively low.Therefore,this paper proposes a Reliability Routing Protocol based on Dynamic Transmission Range(RRDR).By setting the dynamic transmission range,calculating the reliability value of the communication link and various influencing factors to improve the performance of the routing protocol.The characteristics of the RRDR protocol are as follows:(1)A dynamic transmission range algorithm based on local vehicle density is proposed.The local vehicle density is estimated according to the number of neighbor vehicle nodes.The transmission power is adjusted to change the transmission range to adapt to different vehicle densities and improve the connectivity of the network.(2)A reliability model of VANET communication link suitable for urban scenarios is proposed.The driving directions of two vehicle nodes directly communicating in urban environment can be parallel or orthogonal to each other.Different reliability models of communication link are designed based on these two speed relationships.(3)According to the special traffic structure of urban environment,vehicle nodes are classified according to the location of vehicles in the road.Considering link reliability,node location,moving direction and distance from the destination node,forwarding algorithms corresponding to different node types are proposed.They are the Forwarding Algorithm for Vehicles on the Road(FAVR)and the Forwarding Algorithm for Vehicles at Intersections(FAVI),and use eigenvalue vector method to calculate the weight coefficients of the two algorithms.In the simulation process,the map-based moving model is constructed based on the real map.Then RRDR and several comparison routing protocols(GPSR,GPCR,GSR,CAR)are simulated on the NS-3 simulation platform.Through the simulation results,each routing protocol performances are analyzed and compared under different total number of vehicles and vehicles speed.It can be seen that the RRDR protocol presented in this paper has higher data delivery rate,lower end-to-end delay and better routing performance in urban environment.The performance improves the connectivity and stability of the network.