基于小波去噪的OFDM信道估计技术研究

摘要

Channel estimation can provide the necessary channel information for coherent demodulation and space-time decoding in the OFDM system,so it is an indispensable part in the receiver of OFDM system.How to reduce the influence of noise in the wireless channel is an important issue which affects the performance of the entire communication system.This paper proposed a new channel estimation method which applies wavelet de-noising into channel estimation of OFDM system.The initial channel frequency response on the pilot position was obtained from LS algorithm and then was processed by wavelet de-noising; the final channel frequency response of whole carriers was obtained by interpolation.This method can reduce the influence of noise,ICI in the mobile OFDM communication systems and the BER.Simulation results demonstrate that the performance of wavelet de-noising channel estimation method is 2-3 dB better in SNR than conventional method in SISO-OFDM and MIMO-OFDM system.%信道估计能够为OFDM系统提供相干解调和空时译码所必须的信道信息,是OFDM系统接收机中非常重要的一个环节,如何降低无线信道的噪声,提高信道估计精度,是关乎整个通信系统性能的重要问题.提出了一种将小波去噪应用到OFDM系统无线信道估计中的方法,利用LS算法得到导频位置频域响应后进行小波去噪,然后插值得到整个信道的频域响应,可以减少多径衰落信道中的噪声和ICI对于信道估计精度的影响,减少系统的误码率.在SISO-OFDM和MIMO-OFDM系统,无线移动信道环境下的仿真表明,与传统的信道估计方法相比,在低信噪比的情况下,提出的信道估计方法能够提供2-3dB的性能改善.