Design And Implementation Of 5G Vehicle-ground Gateway Based On Embedded Linux

With the increase of high-speed railway data flow,the railway digital mobile communication system(GSM-R)gradually can not meet the needs of high-speed train-ground communication.In recent years,5G network has developed rapidly,and its characteristics of large bandwidth,fast speed and low delay can meet the requirements of high-speed train-ground communication.However,the quality of mobile communication on high-speed trains is greatly affected by such factors as excessive signal penetration loss,frequent switching of base stations,environmental interference and Doppler effect,and the stable communication between high-speed trains and the ground is one of the important conditions for high-speed and safe operation of trains.Based on embedded Linux,this paper designs a 5G vehicle-ground gateway that communicates with the ground through 5G network,so that Ethernet data on the train can be stably sent to the ground server through 5G network after being processed by the gateway.The main contents of this paper include:Theoretically,the gateway and the key protocols used are analyzed,especially the interaction between each protocol layer of 5G protocol when data services are initiated.In terms of hardware,gateway hardware structure is designed according to hardware requirements.The gateway adopts the structure of separating core board and baseboard as a whole,selects a high-performance ARM architecture core board,and designs the power circuit,BOOT configuration circuit,Ethernet circuit,5G mobile communication circuit,RS232 debugging interface circuit and USB interface circuit on the baseboard,so as to build the hardware system of the gateway.In terms of software,firstly transplant Linux system and develop interface driver,then design gateway software according to software requirements to enhance the anti-interference ability of gateway,reduce the influence of network problems caused by frequent switching of base station on vehicle-ground communication,and make vehicle-ground communication more stable.The software design content is as follows: 1)The function of preventing packet loss is designed with data storage function,data encryption function,data integrity verification function and timeout retransmission function;2)The function of disconnection continuation determines the link status through heartbeat packets,and realizes the reconnection of disconnection and data transmission after reconnection;3)Network detection Detects the network through the Ping function,and restarts the network according to the Ping packet loss rate;4)Link switching function Send AT command through serial port to obtain the signal quality of 5G module,and switch the 5G communication link that sends data according to the signal quality.In terms of testing,I built a testing platform and used QT software to design testing software for vehicle data center and ground server.Test software is used to simulate network abnormal scenarios and test and analyze various design functions to verify the functional design objectives of the gateway.