Study On RSU Access And Data Dissemination Based SDN In VANET

With the increase amount of the vehicles and the improvement of Internet service quality,more and more functions need to be achieved in VANET,such as the delivery of accident information,various unsafe applications.These requirements challenge the existing VANENT architecture and network performance.At present,because of the limitation of the RSU coverage and the fixed VANET communication architecture,the traditional V2 I pattern can hardly meet the requirements of various Internet services.For example,when entering the coverage of RSU,some vehicles may use a disordered manner in order to contend for more resources,which would induce the loads imbalance of different RSUs,and the reduction of network throughput.Besides,there are also some problems existing in VANET data dissemination.In VANET,the vehicles need to switch among RSUs frequently on highways due to their high speed and the limitation of RSU coverage.This issue may cause a series of problems such as data transmission interruption and increase of the transmission delay.To solve the problems existing in RSU access and data dissemination,SDN(Software-defined Networking)is introduced,which is the most remarkable technology in the communication network field.The core idea of SDN is to realize the flexible controlling of the network traffic by decoupling the control plane and the data plane of the network equipment.SDN can improve the performance of centralized controlling,programmability and other aspects of the existing architecture significantly.In this paper,we build a SDN-VANET architecture and explain it in detail.Based on this architecture,we study two aspects of VANET including the RSU access and data dissemination.In the scheme of RSU access,first we modify the Open Flow protocol in order to the application of wireless network.Then the BUS is introduced as a mobile RSU to increase access opportunity.Subsequently,we construct a game model about the RSU access.Finally,the access strategy with max profit is formed by running the evolution game model.In the data dissemination strategy,we develop three modules in application layer,including content management,content cutting and pre-cache.By running above modules,a large quantity of communication load can be reduced when vehicles switch among the RSUs on highway.The strategies discussed above are all verified in OPNET and MATLAB simulation.Compared with traditional RSU access,our plan can improve the RSU throughput,achieve the load balance,as well as reduce the RSU switching frequency significantly.By developing the SDN application layer,our data dissemination strategy also shows good performance in reducing transmission delay and retransmission ratio.Through the simulation results,we can draw a conclusion that SDN can solve several problems in RSU access and data dissemination,and also improve the network performance of VANET.In the future,we will study the RSU access in more complex situation,such as multi-RSUs access and the data dissemination strategy in urban road system.