Research And Implementation Of Channel Estimation And Equalization Technology In LTE Downlink

Channel estimation and equalization technology is a very important step in the wireless communication system. It has great significance and value in response to the fading characteristics of wireless channel, to ensure the accuracy of the receiver for processing information and reduce system error rate.According to the cell specific reference signal of LTE downlink system, the techniques of channel estimation and equalization are studied and implemented on the software radio platform. The main contents of this thesis include the following aspects:1. A simulation model is constructed based on multipath Rayleigh fading channel,and three typical power delay spectra EPA, EVA and ETU in LTE are simulated by using this model.2. The classic pilot aided channel estimation algorithm is studied. An improved method of threshold establishment based on the time-domain filtering algorithm is proposed. The simulation results show that the performance is raised to some extent compared with the result of traditional filtering algorithm. At the same time, the interpolation algorithm and equalization algorithm is studied. According to the simulation results and complexity analysis of the algorithm, the temporal filtering algorithm and DFT interpolation algorithm in frequency-domain with the linear interpolation algorithm in time domain and ZF equalization algorithm are selected in the software radio platform for the realization.3. The channel estimation and equalization algorithm is implemented on the software radio platform of USRP and GNU-Radio. At the same time, the defects in threshold filtering algorithm, DFT interpolation algorithm, linear interpolation algorithm and the IDFT/DFT are optimized. Then the field test was done in three different channel environment, the results show that the decoding correct rate of MIB information enhance 17 percent on average after the optimization. The correct rate reached to 99 percent in indoor environment of 20dB, and this index satisfy the project requirements. At the same time, the processing delay of PBCH channel reduced from 2.6ms to 0.51ms, which satisfy the real-time processing needs of 1ms.The research and implementation results show that the implementation and optimization of the LTE downlink channel estimation and equalization algorithm has certain practical value in the software radio platform.