基于小波去噪与离散余弦变换相结合的正交频分复用系统信道估计算法

Channel estimation algorithm for orthogonal frequency division multiplexing based on wavelet de-noising and discrete cosine transform

针对传统的基于离散余弦变换(DCT)信道估计算法没有处理循环前缀之内噪声的问题,提出了一种基于小波去噪与DCT插值相结合的正交频分复用(OFDM)系统信道估计方法。首先,采用最小二乘(LS)法对接收到的导频信号进行信道初步估计;然后,对LS法估计出的结果进行离散小波阈值去噪处理;最后,利用DCT插值对循环前缀内的噪声再次处理,以进一步减小噪声的影响。在Matlab 2012平台上仿真,与传统的基于DCT信道估计算法相比较,误码率相同的条件下,所提算法的信噪比(SNR)性能提升了1 d B左右;均方误差相同的条件下,所提算法的SNR性能提升2 d B左右。仿真实验结果表明,该算法能够较好地减小加性高斯白噪声(AWGN)的影响,并有效提高信道估计的准确度,其总体性能较基于DCT的信道估计算法更优。

In view of the problem that the traditional channel estimation algorithm based on Discrete Cosine Transform （DCT） does not eliminate the noise in the cyclic prefix length, a new method of Orthogonal Frequency Division Multiplexing （OFDM） system channel estimation based on wavelet de-noising and DCT interpolation was proposed. First the method of Least Squares （LS） was used to preliminarily estimate channel for received pilot signal, then the results estimated by LS method were processed through discrete wavelet thresholding denoising, finally the noise of the cyclic prefix length was handled again by DCT interpolation algorithm to further reduce the influence of noise. The simulation on Matlab 2012 platform, compared with the traditional channel estimation algorithm based on DCT, under the conditions of the same Bit-Error-Rate （BER）, the Signal-to-Noise Rate （SNR） performance of the proposed algorithm improved about 1 dB; under the conditions of the same Mean-Square- Error （ MSE）, the SNR performance of the proposed algorithm improved about 2 dB. The simulation results show that the proposed algorithm can not only reduce the influence of Additive White Gaussian Noise （AWGN）, but also improve the accuracy of channel estimation effectively, and the proposed algorithm has better performances than the channel estimation algorithm based on DCT.