Study On The Integration Method Of Train-Ground Communication And Train Control Based On LTE

Communication-Based Train Control(CBTC)systems,as one of the most advanced automatic train control systems,use Wireless Local Area Networks(WLANs)as the conventional train-ground communication technology.However,when applied in urban rail transit environment,WLANs have the disadvantages such as co-channel interference,limited movement speed and poor wireless coverage.As the next wireless communication technology specified by International Railway Union(RIU),Long Term Evolution(LTE)is able to satisfy the basic performance requirements of CBTC systems with better wireless coverage,higher movement speed and extra interference reduction.As one of the new technologies in LTE-Advanced system,Device-to-Device(D2D)communication is able to provide direct communication link between adjacent devices.Therefore,it is worthy to study the fusion of D2D communication in LTE with conventional train-ground communications.Moreover,the wireless transmission errors such as data packet delay and loss will impact CBTC train control performance.Hence the integral design of wireless communication and train control is very important to improve the overall performance of CBTC systems.In this paper,we study the wireless transmission error in LTE system,and design the data transmission method using both train-ground link and D2D link.Cognitive control method is applied in the integral design of wireless communication and train control in LTE-based CBTC systems.Simulation results show that the proposed integral design method can improve CBTC train control performance.The details of the paper are as follows:1)We study the application of LTE in wireless communication of CBTC.First we describe the key technologies of LTE and D2D communications.Then we analyzed the systems structure and advantages of LTE-based CBTC system,and design the information fusion of train-ground link and D2D link.2)We analyze the wireless transmission error of LTE systems.We first analyze transmission delay and packet drop in train-ground link and D2D link.Based on the above analysis,we consider the information fusion and calculate the wireless communication delay and packet drop rate considering both transmission links.The relationship of wireless communication and train control is also briefly discussed in this section.3)We present the integral design method based on LTE and train control using cognitive control method.First we introduce the details of cognitive control.Then we formulate the cognitive control systems model and information gap model of LTE-based CBTC systems.At last we use Q-learning algorithm to calculate the optimal control decision of CBTC performance optimization.4)We perform the field test to verify the availability of LTE-based CBTC systems.Based on the field test data,we use simulation to verify the CBTC system performance of the integral design method proposed in this paper.Simulation results show that the integral design method is able to provide better train control performance and decrease the impact of wireless communications,compared to conventional control method.Moreover,the CBTC performance optimization of the integral design method is much obvious in either worse wireless environment or long running distance environment.