Research On Channel Estimation Technique In LTE-A System

LTE-Advanced which is enhanced program of Long Term Evolution is proposed to meet the performance requirements of the 4th generation mobile communication by3 rd Generation Partnership project. LTE-A continue to use the Orthogonal Frequency Division Multiplexing) and MIMO(Multiple Input Multiple Output) technology as key technologies for physical layer when introducing new technologies. OFDM and MIMO technology can improve system reception performance and transmission rate,but the performance of these key technologies is largely dependent on the accuracy of channel estimation, therefore, research on channel estimation technology is of great significance for LTE-A system.First, this paper briefly introduces the development of mobile communication.Then the fading characteristics of the wireless channel and common channel model for LTE-A system are discussed. After that, the key technologies for LTE-A physical layer are analyzed, focusing on the basic principles and the system model of OFDM and MIMO technologies, followed by summarization of their specific applications in LTE-A uplink and downlink. On the basics of analysis of several typical pilot design,the classic channel estimation algorithms based on pilot of the OFDM system is researched, including least square(LS) channel estimation algorithm, minimum mean square error( MMSE) channel estimation algorithm, linear minimum mean square error(LMMSE) channel estimation algorithm and channel estimation algorithm based on the Discrete Fourier Transform(DFT). And several interpolation algorithms are also studied, including constant interpolation algorithm, first-order linear interpolation algorithm, second-order interpolation algorithm and DFT interpolation algorithm.Then implementation plan of these channel estimation algorithms are proposed by this paper based on cell-specific reference signal(CRS) and demodulation reference signal(DM-RS) in LTE-A downlink. Aimed at the leakage of Channel Impulse Response(CIR) based on DFT channel estimation algorithm, a novel DFT based channel estimation method is proposed, which divide CIR into some segments and reconstruct each segment to approximate the ideal channel CIR and to get idealchannel estimation. Finally, Proposed algorithm and classic channel estimation algorithms are simulated using LTE-A downlink simulation platform built with Matlab simulation results showed that the improved algorithm is efficient.