Research And Implementation Of 5G Wireless Channel Emulation Technology For High-Speed Railway

The 5th Generation Mobile Communication(5G)is currently in a crucial period of rapid development,and China State Railway Group Co.,Ltd has made a clear aim that will develop a railway broadband mobile communication system based on 5G technology.However,the wireless channel characteristics in the high-speed railway scenarios are obviously different from those of the public networks.Therefore,it is particularly important to carry out the performance evaluation of the 5G system in the high-speed railway scenarios before network deployment and equipment exploitation.The channel emulator can accurately emulate the fading characteristics of the external environment in laboratory.It is also of great significance in communication systems design and terminal equipment research.In the high-speed railway scenarios,due to the high-speed movement of trains,the wireless channel has very obvious nonstationary characteristics.But the traditional channel emulator can’t be used for 5G system performance evaluation in high-speed railway scenarios because of assumption that the channel is stationary during emulation.In response to this situation,this thesis designs and develops a 5G wireless channel emulator that can apply in high-speed railway scenarios.The research results can contribute a lot to the development of 5G equipment and network deployment in high-speed railway scenarios.The main work and contributions of this thesis are as follows:(1)The time-varying non-stationary channel emulation method suitable for highspeed railway 5G communication scenarios is studied,and a real-time channel emulation method based on data stream is proposed.Then,the development of channel emulator is established on software radio platform.This method realizes the real-time updating of channel coefficients through an efficient data transmission scheme and a high-precision data interpolation algorithm which meets the requirements of time-varying channel emulation in high-speed mobile scenarios.(2)For the problem of insufficient hardware resources of emulation platform,this thesis designs a fading-emulation method based on collaborative processing architecture.This method uses peer-to-peer data stream technology and high-precision clock synchronization schemes to realize real-time data interaction among Field Programmable Gate Array(FPGA)boards,integrating the resources of multiple FPGAs,overcoming hardware resources limitation on the number of emulation channels,further realizing large-scale emulation and laying the foundation for future emulation of Massive Multiple Iutput Multiple Output(Massive MIMO)system.(3)Based on developed channel emulator,a verification test system is built to test the doppler effect,multipath effect,MIMO channel correlation and other functions.Combined with the high-speed railway channel model specified by the 3rd Generation Partnership Project(3GPP),the real-time emulation function is verified.The test results show that the current performance of the channel emulator could already meet the 5G wireless channel emulation test requirements in high-speed railway scenarios.