Application Research Of Information Acquisition And Communication Technology Based On Cooperative Vehicle Infrastructure

In the age of informationization in highway transportation,intelligent transportation system has been more and more widely used in human's social life.However,traffic congestion and security problems are also getting worse with the sustained growth of vehicles population.Only the close cooperation of people,vehicles and roads can effectively relieve traffic congestion and reduce traffic accidents,which makes people's travel more convenient.Therefore,vehicle infrastructure cooperative system has become one of the hot spots of intelligent traffic research.The nodes of mobile ad hoc networks move quickly and the topology changes frequently in cooperative vehicle infrastructure system(CVIS),so how to make the information interact quickly and accurately in the system is the key point of current research.In this paper,the vehicle information acquisition module is designed under the background of roadway coordination.On the basis of the collected location information,an improved routing algorithm based on geographic location is proposed and implemented,enabling the network to have higher packet delivery rates and lower end-to-end delay.The main researches of this paper are summarized as follows:(1)The information acquisition system based on cooperative vehicle infrastructure system has been designed.The hardware part includes the design of main control circuit,GPS module circuit,CAN(Controller Area Network)interface circuit and power circuit.The software part includes the analysis of GPS data and the acquisition of vehicle CAN network data.The system selects i.MX6 DL integrated with CAN controller as main control chip,TJA1040 as CAN transceiver and cost-effective ublox neo-6m as location chip to collect the movement status and position information of the vehicles.Then analyze and display these data through the development tool QT to realize the functions of real-time acquisition of time,speed,course,longitude and latitude data.(2)The communication routing technology in the cooperative vehicle infrastructure system is studied,and the traditional GPSR(Greedy Perimeter Stateless Routing)based on geographical location is selected to carry out an in-depth algorithm analysis included greedy algorithm,right-handed rule and planar graph routing method.After analyzing the deficiencies and causes of the original routing algorithms in terms of greed forwarding and perimeter forwarding,aiming at the problem of link fracture and path redundancy,an improved routing algorithm based on geographic location is proposed and implemented.The improved routing is based on the premise that each car is equipped with a GPS positioning system and can obtain the real-time position coordinates information.Add the relative position prediction as the judgment criterion in the phase of updating the neighbor list,add the evaluation factor of the link lifetime in the greedy forwarding rule,select the next-hop forwarding node by the direction of the neighbor node in the perimeter forwarding rule,and add fixed nodes at the intersections to change the routing direction more efficiently.The overall improved algorithm can effectively reduce the occurrence of communication link fracture.And because the greedy forwarding strategy is more secure,it reduces the probability of initiating perimeter forwarding and alleviates the path redundancy problem.(3)Simulate and analyze the performance of the traditional and improved GPSR protocol.First of all,use the traffic simulation tool VanetMobiSim to simulate the urban transport scene and vehicle movement following model.Then simulate the traditional GPSR protocol and improved routing protocol in NS2.Finally,write the awk files to analyze the routing trace.Research can get packet delivery rate,end-to-end delay and throughput these three key performance indicators of GPSR and improved routing protocol.It is concluded that the improved routing protocol has higher packet delivery rate,throughput and lower end-to-end delay,making network performance more secure and reliable.