Research On Channel Estimation And Detection Technology Of MIMO-OFDM System Under LTE-R

In recent years,high-speed railways have developed rapidly with the advantages of superior carrying capacity and accelerating driving speed.This puts higher requirements on the quality of railway communication.Therefore,promoting the application of LTE mobile communication technology in high-speed railway wireless broadband communication system has become the focus of current research.However,when the train is driving at high speed,the communication performance of LTE-R system will still be affected by unfavorable factors such as Doppler shift and noise.Hence,effective channel estimation and accurate signal detection are the keys to solve the above problems.This thesis firstly studies the LTE-R communication network architecture and the key technologies of the physical layer,and completes the construction of the MIMO-OFDM system.And then,analyzing the channel estimation algorithm especially for this system,and a channel estimation scheme based on joint Doppler frequency offset estimation is proposed to achieve the purpose of eliminating Doppler frequency offset interference and improving channel estimation accuracy.Secondly,the signal detection technology in the Doppler frequency offset interference system is studied,and the signal detection algorithm under the layered space-time structure is applied to the high-speed rail environment.By analyzing the three types of detection techniques:optimal detection,linear detection and nonlinear measurement,the best performance OSIC signal detection algorithm is selected,and the performance is verified by simulation comparison of high-speed rail WINNERII channel model.Finally,with the NI-USRP hardware experimental platform,this thesis uses Lab VIEW to simulate the WINNERII high-speed rail channel model and builds a 2×2 MIMO-OFDM system.The experimental results show that the system is feasible,and the performance tests in different speeds are carried out.The results show that the proposed channel estimation and signal detection algorithm can be applied to LTE-R,and the system has stable BER performance at different driving speeds,which effectively improves the system communication quality and provides reference for the future physical realization of railway communication system.