| With an active commercial deployment of LTE(Long Term Evolution), LTE test become the common demand of the whole industry chain,channel estimation algorithm as a receiver physical layer, has been the difficult and hot of the mobile communication system research. Channel estimation provide conditions for signal detection, and plays a vital role to the data recovery, so studying channel estimation technique should have the process to the study of LTE receiver and LTE testing. The main content of this paper is to study signal processing of each receiving model of the LTE downlink, focusing on studying each channel estimation module algorithm to find a suitable estimation algorithm for LTE receiver tests. In this dissertation, the bit error rate and mean square error are as the reference indexes.This dissertation analyzes the signal processing of LTE downlink, gives the design principle and the simulation platform designing of each module receives of the downlink LTE system, focusing each estimation algorithm of channel estimation module for LTE receiver system to do a detailed analysis comparison, and the introduction of DCT(Discrete Cosine Transform) based estimation algorithm which can effectively reduce the signal energy leaks and algorithm complexity, but this algorithm to estimate the performance of the non- pilot comb away and not have significantly improved, in order to solve this problem, an improved algorithm based on DCT is proposed, the improved algorithm more pronounced to solve noise suppression and inhibition of energy leakage problem. And analyzed the channel characteristic of LTE downlink, proposed an improved modeling algorithm for LTE MIMO multipath fading, can effectively eliminate the relevance, improve spectral quality and reduce spectral leakage, for the subsequent conduct LTE downlink between different paths each link module design simulation, in particular to provide a channel estimation module according to channel information.It builds the LTE downlink baseband system through MATLAB simulation platform, and gives the Graphical User Interface(GUI)of user which the users can choose the different operating modes of the system and set the custom parameters. And then it verifies the impact of the algorithm for LTE downlink system channel estimation in the system. Through a large simulation can be drawn LMMSE algorithm estimates the performance of the pilot is optimal at high than the LS algorithm about 2.2dB; improve the performance of the DCT algorithm estimates the interpolation process is optimal, than polynomial interpolation algorithm improves about 6dB, improve time-domain interpolation algorithm than about 3.5dB, and moderate complexity of the algorithm. Therefore, the best algorithm of estimator in the pilots is LMMSE, and the best algorithm of estimation in the data subcarrier is the improved DCT algorithm. Finally, all channel estimation algorithm discussed in this paper is packaged, which can call for the program of other communication systems. |
