Research On Performance And Routing Protocols Of Cooperative Vehicular Networks

In recent years,the increase in the number of vehicles has brought huge challenges to the transportation industry.The Internet of Vehicles has attracted attention of researchers since it can alleviate traffic congestion and provide users with safe passage,entertainment and other services.However,the high-mobility of vehicles in the Internet of Vehicles will easily lead to the change of network topology,and the quality of communication between vehicle nodes will also decline.To deal with this problem,the researchers introduced cooperative communication technology in the Internet of Vehicles and constructed a new type of cooperative vehicular network.It is found that the new architecture greatly enhances the reliability of network transmission.Focusing on the cooperative vehicular network,this paper mainly completes the following work: first,it introduces the related technologies,characteristics and challenges of the network;secondly,it expounds the theoretical basis of this study,including performance evaluation parameters and routing protocols;finally,it analyzes the data transmission process,and provides some optimization schemes from two aspects of transmission capacity and delay.Specifically,the main contents of this paper are as follows:(1)In this paper,the performance of cooperative vehicular network is studied based on the highway scene In this scenario,the signal in the vehicle to infrastructures communication area is subject to Rayleigh fading,and the signal in the vehicle to vehicle communication area is subject to Nakagami fading,and the mutual interference between vehicle transmission nodes is also considered.In order to comprehensively analyze the capacity of the cooperative vehicular network,an analysis framework is established,a closed expression of the transmission capacity is derived,and the correlation between system performance and other network parameters under the joint influence of fading and interference is revealed.Theoretical analysis and simulation results show that the system capacity initially increases with the number of collaborative vehicles,and then decreases.In order to achieve the balance between the number of cooperative vehicles and the system capacity,the approximate solution of the optimal cooperative vehicle ratio was obtained by Newton’s iterative method.It is not difficult to find that this optimal ratio and other simulation results can provide some guidance for designing a higher-performance cooperative vehicle network.(2)Aiming at optimizing the end-to-end delay,this paper studies the routing protocol of the cooperative vehicular network in urban scene.Considering the difference between urban intersections and straight roads,different mathematical tools were used for modeling research.For the intersection path,the fuzzy mathematics evaluation method is selected.Specifically,based on the three factors of vehicular density,segment load,and segment connectivity,a fuzzy logic evaluation system was established,and the segment with the highest evaluation was found.For straight roads,in order to select the next hop relay node,the directed weight graph of the road is established,and the improved Dijkstra algorithm is proposed with the end-to-end delay as the optimization objective.The algorithm uses depth-first search to reduce the search range of nodes,establishes a new topology subgraph,and modifies the algorithm weights to meet the optimization problem.Simulation results show that the algorithm proposed in this paper greatly reduces the time complexity and achieves better performance,including improving the packet transmission rate and reducing the network delay.