Modeling And Simulation Research On Vehicular Ad Hoc Networks Of Intelligent Transportation System Based On Internet Of Things

With the rapid development of the modern city,the urban traffic system faces many problems,such as traffic management falling behind,incomplete urban road network planning,and vehicular quantity sharply increasing.These problems have resulted in heavy traffic congestion,which has now become a serious issue.The Intelligent Transportation System(ITS)conducted significant research to solve the traffic congestion problem.Vehicular Ad Hoc Network(VANET)is an important application of Internet of Things in ITS.Per real traffic scenarios,the VANET is mainly divided into Vehicle-to-Infrastructure(V2I)and Vehicle-to-Vehicle(V2V).Research on VANET has shown that it can effectively alleviate traffic congestion,improve traffic conditions,and improve passenger comfort.Current research on VANET is based on simulation.As the experimental method for obtaining communication data of VANET is rather expensive and difficult,the traffic simulation is one of the most effective methods in obtaining data.In this thesis,the microscopic model and simulation of VANET using OPNET Modeler software are listed below.(1)Define the VANET hierarchical protocol model based on Internet of ThingsThe five layers of the protocol model from low to high are the physical layer,data link layer,network layer,transport layer,and application layer.In the VANET simulation platform,the physical layer and the data link layer specifically use 802.11 p protocols.The network layer performance could be improved by modifying the layer routing protocols.The transport layer and application layer protocols are mature.(2)Set up vehicle movement model of VANET based on Internet of ThingsWe set up the vehicle movement model of VANET using OPNET Modeler software.The vehicle model and actual program is limited by its structure.However,we could modify its modules to solve the problem.OPNET Modeler adopts the Hierarchical Network Modeling.From the protocol's point of view,the node module conforms to the OSI(Open System Interconnection)standard.Thus,the layers from bottom to top are the physical layer,the MAC(Medium Access Control)layer,the ARP(Address Resolution Protocol)layer,the IP(Internet Protocol)encapsulation layer,the IP layer,the TCP(Transmission Control Protocol)Layer,and the Service layer.(3)Study MAC layer of VANET of ITS based on Internet of Things(1)Modeling and simulation of VANET of V2 I in one-way one-laneIn the urban traffic scenario,in addition to intersecting,the vehicle nodes were linearly distributed.Because the network topology changed little,unnecessary factors were ignored in the simulation process.The vehicle model was established.(2)Modeling and simulation of VANET of V2 I in two-way two-laneIn the single hop scenario of VANET the information in the vehicle-vehicle included single hop communication because the transmission distance was short.When the vehicle's speed changed,it did not affect the communication performance of VANET.When the communication range of the vehicle expanded,the communication continual time increased.In the same process,the load,throughput,and delay of information were not affected.(4)MANET routing algorithms and advanced routing protocolIn the VANET of ITS based on Internet of Things multi hop scenario for V2 V network,the experimental results showed that Ad Hoc on Demand Distance Vector(AODV)protocol was more suitable than Dynamic Source Routing(DSR)protocol for VANET in throughput,delay,routing load,packet loss rate,and average routing hops.(5)The secure application of VANET of ITS based on Internet of ThingsThe transport layer and application layer have a mature protocol.They carried out modeling and simulation for V2 I of VANET.Two sets of On Board Unit(OBU)are installed on a vehicle,and they operate in parallel.During a hand-off,at least one network interface on the vehicle is available.Therefore,the vehicle speed could affect the hand-off with a set of OBU,but vehicle speed does not impact communication for two sets of OBU.The study applies the characteristics and advantages of the Internet of Things with microscopic simulation research.The results were vehicle precision identification,road network dynamic monitoring,and traffic control dispatching real-time precision targeting.Our work is sponsored by Nature Science Foundation of Gansu,China under Grant No.1310RJZA071 and is supported by College and University Science Research Project of Gansu,China under Grant No.2016B-031.