Research And Implementation Of Key Technologies Of Railway Communication Network Simulation

As the core equipment in our country’s high-speed railway communication system,CTCS-3 train control system undertakes the important task of ensuring the safe operation of trains in complex transportation networks.The CTCS-3 train control system includes on-board equipment and ground equipment.The GSM-R network is the transmission channel of the two-way data between the vehicle and the ground.Therefore,the quality of the GSM-R network seriously affects the quality of the information transmission between the vehicle and the ground.However,the existing GSM-R network equipment is complex and expensive,which makes it impossible to directly complete the network test in the laboratory environment.Therefore,in order to meet the requirements of the two-way transmission test between the vehicle and the ground,this paper researches and develops the GSM-R network simulation system to complete the vehicle-ground,vehicle-to-vehicle Requirements for wireless network interaction.This paper analyzes the difference between GSM network and GSM-R network,investigates the current GSM wireless network simulation scheme and PBX simulation scheme,deeply studies the realization principle of the above scheme,and designs and implements the GSM-R network simulation system.The main research work of this paper is as follows:1.Propose a scheme of network emulation wireless interface design based on OpenBTS.Aiming at the problem of simulating communication base stations,this scheme proposes the realization technology of simulated full-rate data traffic channel and fast associated control channel.The full-rate data traffic channel unit is used to simulate the TCH/F4.8 function of the full-rate data traffic channel,and the fast channel-associated control channel emulation realizes the fast channel-associated control channel encoding and decoding and data transmission capabilities,and realizes the insertion and marking of TCH bursts.The solution includes SDR transceiver module and BTS simulation module.After comparing the SDR transceiver and selecting B210,the BTS simulation module will be re-developed on the basis of OpenBTS,which solves the implementation problems of the bearer channel and control channel of transparent transmission of service data from the software..2.Propose a relay gateway scheme based on PBX simulation.Aiming at the problem that the signaling protocol of the simulated wireless base station does not match with the ISDN signaling protocol,this scheme proposes a technology to connect the SIP protocol and the DSS1 protocol.Aiming at the MOC type call control process,the corresponding rules for the translation of signaling connection primitives are designed and implemented,and the connection of the signaling process is realized.The interaction between the BTS emulation module and the ISDN signaling is realized,and the signaling processes such as call chain establishment,data transmission control,and link removal of data calls are completed normally.Aiming at the match between the simulated wireless data rate and the fixed network interface rate and the occurrence of packet loss and delay jitter,a simulation rate matching technology based on the V.1 10 protocol is proposed,which completes the rate classification adaptation and timing transmission and reception in the simulated concurrent multi-connection situation.,missing frame filling and other functions.The basic data rate of the air interface of the base station can be adapted to the data rate of the ISDN B channel,and stable forwarding can be maintained in the event of packet loss and delay jitter on the wireless side and out-of-sync on the fixed network interface side.3.The realization of GSM-R network simulation system based on software radio.Analyze the system requirements,design the overall architecture of the system,and realize the development of the network simulation wireless interface based on OpenBTS and the relay gateway function development based on PBX simulation proposed in this paper.Endto-end data interaction,presenting a friendly visual display interface.After completing the development and testing in the actual scene,the system can run stably for a long time.According to the test results,the vehicle-mounted ATP equipment can establish a call connection with the ground RBC equipment within 5s,and supports the connection of 7 devices at the same time.