Research And Implementation Of A Multi-mode Multi-channel Wireless Train-ground Communication Method

Wireless train-ground communication technology is a key technology in intelligent transportation system,especially in the field of rail transit,trolleybus and other applications.It can be applied to obtain TCMS sub-system,PIS sub-system and other comprehensive monitoring information,and is the core technology to ensure the safe operation of the vehicle.In order to monitor onboard device status and location information of the vehicle,reliable wireless transmission plays a very important role.In a transmission system using a public network,the coverage of a base station along the vehicle running path may be discontinuous,and a single communication mode of train-ground is unreliable.Multi-mode and multi-channel wireless transmission can effectively solve the problems,such as instability,poor reliability and signal coverage in single mode.Based on the features of different kinds of mobile wireless communication,a hybrid 2G/3G/4G multi-mode wireless train-ground communication system is designed.The system can use the 3G/4G,TDD-LTE and FDD-LTE,WIFI and so on hybrid multi-mode multi-channel communication,and it will send a variety of data sources to the ground center according to its different properties,in order to effectively increase the network communication bandwidth.Based on the designed hardware system,the channel management mechanism and multi-mode multi-channel switching method based on 2G,3G,4G and WLAN are explored.The content includes,1)the multi-channel management mechanism based on the analytic hierarchy process(ahp)and entropy value method is employed to manage multiple network communication.2)The network switching decisions scheduling method is presented,which can effectively solve the problem of vertical channel switching.And during switching process,it uses IP address repackaging strategy and automatically obtains and analyzes dynamic IP of vehicle-mounted mobile terminals through server program of the ground data center for actual IP and port of vehicle-mounted mobile terminal,to ensure the continuity of the transmission task and to reduce packet loss rate caused by the switch during transmission.Finally,the practicality of method and the function of the system is confirmed by experiment.With the designed HW system and the proposed multi-mode multi-channel channel management and channel switching method,the reliability and stability of data transmission can be improved,which can effectively solve the coverage issue in single channel mode.The vehicle communication service quality(QoS)can be effectively improved.