Design And Implementation Of LTE Channel Estimation

The content of this thesis is from the national key scientific apparatus develop project(2012YQ20022404)“ the research and development of High performance spectrum analyzer ”.To meet the demand of the project,the main contents are concentrated on the LTE uplink and downlink channel estimation.1.The research and verification of LTE channel estimation algorithms.Firstly,to deal with the problem of inadequate accuracy of Least squares,Minimum Mean Square Error,Discrete Fourier Transform,Discrete Cosine Transform and Discrete Wavelet Transform algorithms are studied.Secondly,to tackle the estimation precision problem in linear interpolation algorithm,Lagrange interpolation and interpolation in transform domains are researched.Finally,constrained by physical layer structure and wireless channel characteristics in the 3GPP protocol,the equivalent link model containing transmitter,channels,and receiver is designed and implemented according to the different modulation mode.Based on the equivalent link,the variable-controlling approach is adopted to compare the channel algorithms with the bit error rate and Error Vector Magnitude as the indexes.Considered the algorithms accuracy and complexity,Discrete Wavelet Transform,Discrete Cosine Transform,and Lagrange algorithms outperforms the others and could be utilized as the channel estimation algorithms in this project.2.The design and implementation of channel estimation module in LTE test and analysis systems.The difference between the pilots patterns of uplink and downlink are exploited to deal different channel estimation design and implementation method in uplink and downlink considering the implementation complexity.In the position of uplink and downlink pilots,the Discrete Wavelet Transform is adopted;in the uplink data position,time domain Lagrange interpolation algorithm is adopted and in the downlink data position frequency domain Discrete Cosine Transform cascade connection with time domain linear interpolation algorithms is used.Required by the project,the designed algorithms are test with actual data combined with TD-LTE uplink and downlink signals test and analysis system and take EVM as the critical index.Results show that the EVM values of the implemented system are within the criterion of1.3 times of the EVM of Agilent 89600 VSA,and satisfying withth erequirement of the project.