OFDM 系统迭代脉冲噪声抑制与信道估计方法

Aiming at the problem that impulsive noise deteriorates the bit error rate performance of orthogonal frequency division multiplexing (OFDM) underwater acoustic communication system, an iterative impulsive noise mitigation and channel estimation method is proposed. Firstly, the symmetric alpha stable (SαS) distribution is introduced to model underwater noise and validated by fitting the measured noise data. Secondly, based on the large amplitude property of the impulsive noise, impulsive noise detection and mitigation are respectively performed on the real and imaginary parts of the received baseband signal by Chebyshev inequality. And through analyzing the statistical characteristics of estimation error of the least squares (LS) channel estimation algorithm, an adaptive threshold LS channel estimation algorithm is proposed to reduce the impact of residual noise. Finally, combining the estimated channel and decoding results to reconstruct noise and estimate impulsive noise, the impulsive noise mitigation and channel estimation are iteratively performed. Simulation results demonstrate that under different levels of impulsive noise and measured noise, the proposed method can effectively suppress impulsive noise and significantly reduce the bit error rate of OFDM system.