基于阈值自适应的小波增强信道估计技术

Enhanced Channel Estimation Technique Based on Adaptive Wavelet Threshold

针对MIMO-OFDM系统导频辅助信道估计算法在低信噪比条件下存在信道估计精度不足或无法收敛等问题,提出了一种基于阈值自适应的小波增强信道估计算法。该算法首先对频域最小二乘估计的结果进行共轭对称处理,然后对IDFT变换之后得到的时域信道采用阈值自适应调整的小波去噪方法,进一步抑制了保留路径的噪声干扰。理论分析和仿真结果表明,文章算法以较小的复杂度代价换取低信噪比条件下信道估计精度的显著提高。

There are some problems in the pilot aided channel estimation algorithm under the condition of low SNR for the MIMO-OFDM system, such as accuracy deficiency, no convergence, etc. This paper proposes an improved DFT-CE algorithm based on the de-noising with adaptive wavelet threshold. To make the estimated channel matrix of the frequency domain conjugate and symmetric, the algorithm firstly handles the estimated results of the least squares by conjugate symmetry, and then transforms the channel matrix to time domain by IDFT. In order to restrain noise interference of the final value after the DTF-CE algorithm, this paper executes the de-noising based on wavelet. Theoretical analysis and simulation results show that the algorithm in this paper can significantly improve the accuracy of channel estimation with a limited increase in complexity.