Research On The Channel Estimation Algorithm Based On Long Term Evolution Downlink

LTE system is a new generation system on wireless communication, which is designed for integration mobile communication and broadband wireless access technology. Its uplink supports the single-carrier frequency division multiple access scheme, and in the downlink orthogonal frequency division multiple access technology is adopted. And meanwhile, it supports the multi-antenna technology which is called MIMO, Multiple Input Multiple Output. This combining technology in LTE downlink system could expand the capacity of communications and greatly improve the rate of data transmission. However, the technology of channel estimation is very significant for synchronization and signal detection, and it has an important influence on related demodulation and can improve the performance of the receiver system.Firstly, this article briefly describes the development of LTE technology and its related background, and summaries the current study and the commercial status of the LTE system, and then makes an overview of the basic principles of the physical layer protocol. OFDM technology and the multiple input multiple output antenna technology are simply described, after that, discussions and presentations about the wireless channel characteristics and common fading channel model are made on the mobile communication system. Secondly, the summarize and some derivation of OFDM channel estimation algorithms in the downlink LTE system are carried out, which contain least squares algorithm, the estimation algorithm based on the criteria of minimum mean square error and the common channel estimation method based on Discrete Fourier Transform, and then it introduces several channel interpolation algorithms. And after the introduction of the virtual carrier, the simulation and comparative analysis are carried on traditional channel estimation method and the DCT-based channel estimation algorithm.And then several simulation plans are made for the better window program, and in order to mitigate the impacts of edge effects, the edge value repetition method is used to compensate for the channel response on the missing virtual carrier. This article focuses on an optimization estimation method based on wavelet decomposition. After the simulation compared with other related algorithms, simulation results show that the performance of the method based on wavelet decomposition is better than the performance of the traditional DFT algorithm. The traditional estimation algorithm and the proposed channel estimation algorithm are also simulated in the MIMO antenna system of LTE, and the simulation results and further analysis indicate the performance gain of the multi-antenna system and verify the validity of the channel estimation methods.Finally, through the comparison between DCT algorithm and DFT algorithm, a channel estimation algorithm of wavelet decomposition joint with discrete cosine transform is proposed, which makes use of DCT/IDCT to replace the traditional IDFT/DFT operation. The algorithms are simulated respectively in the LTE single antenna system and MIMO antenna system, and the simulation results depict that the performance of the optimization algorithm is better than the algorithm based on wavelet decomposition.