Research On Emulation Methods And Performance Of High-speed Moving Scenes Based On Rate Conversion

With the rapid development of high-speed railway(HSR),railway mobile communication systems under high-speed environments are also facing great challenges.Current Global System for Mobile Communications for Railway system(GSM-R)can’t meet the increasing new requirements such as high speed,large bandwidth,low latency,and high service quality.As a result,it is of great significance to research and develop a new-generation railway dedicated mobile communication system.The communication system in the high-speed mobile environment has the characteristics of diverse scenes and large Doppler shifts,which is different from the public network.Therefore,it is very important to measure and evaluate the communication system in the high-speed mobile scene.Some technical methods such as virtual drive test,semi-physical emulation and field measurement are usually used.But the technology of virtual drive test is still in development,semi-physical simulation is difficult to accurately model the channel.HSR filed measurement can fully obtain the channel information and system performance.But the measurement activities are complex and costly,and it is difficult to coordinate with relevant railway departments.In this paper,the method of signal rate conversion is used to emulate high-speed mobile scenes.In order to severely decrease the cost and complexity of high-speed measurement campaigns,the high-speed mobile emulation method induces effects caused by highly-time varying channels on the symbol while conducting measurements at low speeds.Combined with the high-speed mobile emulation method,the high-speed analog channel measurement system is developed and applied.Based on this platform,the field measurement is carried out,the measurement results are analyzed,and the feasibility of the method is verified from the perspective of wireless channels.Finally,a performance verification system using high-speed emulation method in laboratory environment is developed.Compared with results of channel emulator,the performance under different scenarios is verified and applicability of the method is analyzed.The main contributions of this thesis are listed below:(1)By studying high-speed mobile emulation methods,a high-speed mobile analog channel measurement system based on rate conversion is developed and built.This measurement system can realize the functions of signal transmission,signal reception and rate conversion.The calculation method of channel impulse response is analyzed.A high-speed mobile emulation channel measurement is developed and carried out.Based on the extracted channel impulse response of signal,the path loss,shadow fading,small-scale fading and other wireless channel characteristic parameters are further calculated and analyzed to verify the feasibility of the high-speed mobile emulation method.(2)In the laboratory environment,taking the Long Term Evolution(LTE)system as an example,a high-speed mobile emulation performance test verification system is developed combined with the LTE open source platform and channel simulator.Functions such as rate conversion and performance test index statistics have been completed.Developed a comparison verification test plan with the channel emulator,and conducted performance comparison verification tests under the standard fading model,indistinguishable single-path,and two-path conditions.Block error rate affected by the wireless channel is analyzed and the feasibility and applicability of the emulation method is compared and verified.