基于非参数平滑的OFDM系统信道估计算法

Nonparametric Smoothing-based Channel Estimation for OFDM Systems

研究了双衰落信道下正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中信道估计的非参数方法。提出的方案首先利用梳状导频或散布导频和最小二乘算法估计出导频处的信道频率响应并进行简单的分段线性插值,然后用基于非参数统计方法的Savitzky-Golay平滑滤波器对插值后的信道估计值进行非参数平滑。与传统信道估计算法相比,算法大大降低了信道估计的均方误差、系统的误符号率和计算复杂度,运算量仅正比于有效子载波数,且对多普勒频移具有很强的鲁棒性。数值仿真结果证明了上述结论的正确性。统计检验结果表明,该算法在最小二乘意义下是最优的。

A nonparametric smoothing technique based least-Square （LS） channel estimation scheme for mobile Orthogonal Frequency Division Multiplexing （OFDM） communication systems over the doubly selective fading channel was investigated. In the proposed method, the doubly selective fading channel is firstly estimated via pilots arranged in blocktype, comb-type or distributed pilot scheme, piece-wise linear interpolated and at last smoothed by nonparametric Savitzky-Golay smoothing filter. The last smoothing procedure greatly decreases the estimation error introduced by channel noise and interpolation error so achieves better mean square error （/VISE） performance and symbol error rate （SER） performance than the conventional interpolation method such as linear interpolation and DFT-based interpolation, and the error floor is greatly decreased compared to DFT-based interpolation scheme. The computational complexity increased by the smoothing procedure is only linearly proportional to the effective subcarrier-number. Simulations show the performance improvements offered by our approach to the existing ones. Statistical tests show that the scheme is optimum under the sense of least square.