Design And Implementation Of C-V2X Technology In Urban Rail Transit Collaborative Driving

With the continuous acceleration of urbanization process in China,traffic congestion is becoming more and more serious,and urban rail transit with large passenger capacity and high transportation efficiency has become an inevitable choice to alleviate the problem of urban traffic congestion.At present,the urban rail transit industry mainly adopts CBTC(Communication Based Train Control System)system to realize the control of trains.However,with its large-scale promotion and commercialization,the problems it exposes are more and more obvious.On the one hand,there are many ground auxiliary equipments and complicated interfaces,which leads to high construction cost and large maintenance workload.On the other hand,the WLAN(Wireless Local Area Networks)technology adopted by the system has defects such as poor mobility,multiple interference sources and small coverage.With the concept of vehicle-to-vehicle communication put forward in the field of urban rail transit,the V2X(Vehicle to Everything)technology,which has developed rapidly in Intelligent Connected Vehicle,enters people's attention.Therefore,it is worth studying to integrate V2X technology with the existing urban rail transit communication system.This paper comprehensively considers the problems to be solved in the application of V2X technology in the field of urban rail transit.Firstly,aiming at the problem that C-V2X(Cellular Vehicle-to-Everything)and DSRC(Dedicated Short Range Communications)share the spectrum near 5.9 GHz,a shared spectrum resource mechanism based on data link layer is proposed.After studying the underlying of the two technologies,the resource selection algorithms of the two technologies are modeled systematically.Finally,in order to verify the feasibility of the shared spectrum mechanism,a system-level simulation platform is built to evaluate its communication performance.The results show that the mechanism can guarantee that both technologies have sufficient resources to carry out vehicle networking services,and reduce the interference between systems while ensuring the fairness of the channel.In the process of studying the two technical standards of V2X,it is found that C-V2X has better performance and can be extended on the existing LTE(Long Term Evolution)equipment,thus C-V2X is selected to be applied in the field of urban rail transit.This paper first analyzes the requirements and characteristics of the vehicle-to-vehicle communication system,and then designs the system framework of the vehicle-to-vehicle communication system based on C-V2X,and divides the functions of each part.On this basis,the cooperative driving mechanism based on vehicle-to-vehicle communication is designed after analyzing the cooperative principle.Finally,combining with the actual scene,the performance of the system is evaluated through simulation.Comparing with CBTC system,the C-V2X based vehicle-to-vehicle communication system reduces the reserved distance generated by the communication delay,shortens the tracking distance and increases the capacity of the system,which leads to improve efficiency of the urban rail transit system.