Research On Data Forwarding Scheme Of Highway Dark Area In VANET

Vehicle Ad-hoc Network(VANET)is an important part of Internet of Vehicles.The application of VANET technology in the dark area(DA)on highways is a key method to realize the seamless network connection.Users in the VANET environment want to be able to access the Internet easily and conveniently anytime,anywhere.However,this is difficult to achieve in the highway environment.The high-speed movement of vehicles on highways may easily cause problems such as frequent topology switching and short link lifetime.It is very important to design an efficient routing protocol for VANET to optimize data forwarding of dark area on highways and improve network transmission performance between vehicles.This paper mainly studies the application of VANET in the highway scene.Considering the problem that data cannot be continuously and efficiently transmitted in dark area of communication on highways,an improved AODV protocol,named TD?AODV(Improved AODV Routing Protocol Based on Network Transmission Delay),is proposed,which is based on network transmission delay in cluster structure.The main contents of the study include:Firstly,studying data transmission in VANET from the perspective of physical layer connectivity.The connectivity of physical layer is the basic requirement to realize data transmission in VANET.In order to evaluate the connectivity performance of VANET in the highway scene,a connectivity probability analysis model in single-lane environment is established based on the Cumulative Distribution Function(CDF)of the adjacent vehicle distance and considering the minimum safety distance,channel environment,and other factors.The simulation results show the relationship between connectivity of VANET and factors such as the vehicle single-hop communication radius and the vehicle density on the road.Meanwhile,the optimal connectivity condition for single-lane inter-vehicle communication are theoretically predicted based on the simulation results.Secondly,the traditional AODV protocol is improved and designed from the perspective of network layer protocol to improve the data transmission performance at the network layer.Aiming at the problem of the low efficiency of data forwarding caused by intermittent connection of the network on highways,the idea of clustering is introduced into the inter-vehicle communication.At the same time,considering the inadaptability of the traditional AODV routing protocol applied to the VANET on highways and the requirement for delay of inter-vehicle message transmission in cluster structure,an improved TD?AODV Protocol based on network transmission delay in cluster structure is proposed to plan the path of data forwarding.The improved protocol estimates the forwarding performance of the cluster by applying the queuing theory model at the head of the cluster,and takes the obtained forwarding delay of the cluster as the weight of the link between clusters,then the Dijkstra algorithm is used to obtain the shortest delay path to the cluster of the destination node for data forwarding.Finally,based on the OPNET simulation platform,the TD?AODV protocol is respectively simulated under different number of vehicles and different vehicle speeds,and compared with the traditional AODV protocol.The network performance of the two protocols is compared and analyzed through the simulation results.The results of the simulation show that the performance such as packet delivery rate and transmission delay of the improved protocol have been effectively improved.