窄带干扰条件下水声OFDM系统LMMSE信道估计算法

因为正交频分复用（OFDM）系统中强窄带干扰引起水声信道估计性能退化,因此,提出了一种可实用的线性最小均方误差（LMMSE）信道估计方法.该方法结合最小二乘（LS）信道估计结果对受窄带干扰（NBJ）和加性高斯白噪声（AWGN）噪声干扰的导频子载波进行辨别,从而获得最有效信道抽头;根据导出的理论模型,给出了信道自相关、窄带干扰信号和噪声功率等参数的近似估计方法;并采用傅里叶变换以避免矩阵的求逆运算,减少了计算复杂度.仿真结果表明,在强干扰信号条件下,文中提出的方法接近理想状态的LMMSE方法.

LMMSE Channel Estimation Method for Underwater Acoustic OFDM Systems under Narrow-band Jamming

Because of estimation performance degeneration for the underwater acoustic channel induced strong narrow-band jamming （NBJ） in orthogonal frequency division multi -plexing （OFDM） sys- tems, a practical linear minimum mean-squared error （LMMSE） algorithm is proposed. By the meth- od,the pilot sub-carries, which jammed by narrow-band jamming（NBJ）signals and additive white Gaussian noise （AWGN）, are discriminated using least square （LS） estimation results and then the most significant channels taps are found. And the approximate estimation for some key parameters, such as channel autocorrelation, narrow-band jamming signal power and noise power, are provided based on the deduced theoretical model. The inverse operation of a large dimension matrix is avoided by using the fast Fourier transform （FFT） operation, therefore the computational complexity is sig- nificantly reduced. The simulation results show that the performance of proposed method is close to that of the LMMSE method.