| The rapid development of rail transit provides great convenience for urban transportation and public travel.At the same time,the risk of unexpected events in rail transit increases.In this case,the design of vehicle-to-ground wireless communication system is more demanding.Through the design of vehicle-to-ground wireless communication system,the communication between base and the train is strengthened to ensure the safety,stability and solving unexpected events of train.Based on this high standard requirement,TD-LTE has been applied in vehicle-to-ground wireless communication system for its advantages of high data throughput,high frequency spectrum utilization,flexible bandwidth configuration,low system delay,perfect multi-level QOS,high speed mobility and so on.Based on the remarkable characteristics of TD-LTE system,this paper proposes a design scheme of vehicle-ground wireless communication system which integrates trunking scheduling and CBTC service carrying.Firstly,the application status of TD-LTE system is summarized.Secondly,the characteristics of TD-LTE system and the composition of typical vehicle-ground wireless communication system are introduced.After that,by studying the composition of vehicle-ground wireless communication system,taking typical application of CBTC+trunking dispatching as an example,the network composition and subsystems of vehicle-ground wireless communication system are discussed,including control core network and station side.Wireless field coverage,wireless system services,application systems and terminal design.According to the actual situation of the project,the author puts forward some optimization schemes,which mainly include the following aspects:1.Redundant backup of core network and base station equipment is proposed to improve the reliability of the system.2.The field coverage optimization schemes in different scenarios are proposed,and the handover scheme is studied.The communication quality is further improved.3.The internal and external interference of wireless communication system is analyzed,and some anti-interference measures are given.4.In view of the current situation that different lines in the same city can not be interconnected by different wireless communication system equipments provided by different manufacturers,this paper proposes a solution to interconnect with other LTE systems and TETRA systems,realizes the interconnection of different broadband manufacturers or broadband systems,and provides a broader choice for metro operation in the field of urban rail transit.After that,through LTE trunking system function test and LTE-M performance test(CBTC service carrying and system transmission performance),it is verified that the proposed design can provide reliable trunking scheduling function,and can meet the needs of CBTC service carrying.Finally,the research content of the paper is summarized and the follow-up work is planned. |
