Research On Vehicle-ground Communications For Modern Tram Based On 4G-LTE

Nowadays the modern trams under development is the representative of the new era of the transportation,which have undergone significant changes and improvements in appearance and service requirements which is different from the old-fashioned trams.Generally,the research of interconnection between modern trams and the ground is divided into two sections: a section is the interconnection of the Modern Tramway Automatic Control Supervision(ATS)and the modern tram,and another section is the interconnection of the Wayside Control Unit(WCU)and the modern tram.The mutual communication between the modern tram can mainly manifested in two aspects.In the one hands,the modern trams mainly provides data information includes that the running status and position information of the modern tram to ATS communication module.In the another hands,the ATS communication module introduce the information that the control commands and operation plans towards the modern trams.The intercommunication between the modern tram and the WCU communication module is to realize that he modern tram obtain the states and occupation situation of the front approach by WCU module.Firstly,according to the operating characteristics of modern trams and the vehicle-to-ground wireless communication requirements of three business subsystems,thesis compares the current mainstream car-ground communication WLAN wireless LAN technology with 4G-LTE technology,and analyzes the system reliability when 4G-LTE,as a vehicle-to-ground transmission network-transmit network,replace WLAN.Further evaluates the transmission performance of 4G-LTE network through the security requirements of communication by train control,and gives the network architecture of the tram-ground communication system based on 4G-LTE.Secondly,the vehicle-to-ground wireless communication system is simulated through software design and hardware optimization simulation,which achieves from the two aspects of vehicle equipment and ground equipment.Designing and simulating the work-flow and data transmission and reception process of three communication modules,such as vehicle communication module,ATS communication module and WCU communication module.For the hardware part of the modern tram car-ground communication module,the peripheral circuit of the vehicle communication module is optimized.Designing the modern railcar-ground wireless security communication in 4G-LTE environment in detail.Finally,detecting whether the network environment designed in thesis reaches the4G-LTE network environment by the OPNET simulation software and the analysis method of transmission error.On this basis,the system verification of the vehicle ground communication system is designed in thesis throng three parts,which including receiving the packet loss rateof the data packet from the terrestrial communication module in the 4G-LET and WLAN environment by the in-vehicle device when no data is re-transmitted,receiving the packet loss rate of data re-transmission and secondary re-transmission in the same coding mode as Adaptive Modulation and Coding(AMC),and Hybrid Automatic Repeat Quest(HARQ)the system delay under re-transmission.