Impulsive noise estimation for underwater acoustic OFDM communication using signal-noise separation and distributed compressed sensing methods

In underwater acoustic (UWA) orthogonal frequency division multiplexing systems, impulsive noise and carrier frequency offsets (CFOs) may contaminate subcarriers. Traditionally, CFOs and impulsive noise are estimated using null subcarriers, reducing spectral efficiency. This article proposes a signal-noise separation based and distributed compressed sensing based method to jointly estimate impulsive noise, channels, and CFOs using only pilot subcarriers, thereby significantly improving spectral efficiency. Specifically, the signal- noise separation method segregates channel and impulsive noise portions in a specific orthogonal subspace, preventing error propagation. To further facilitate impulsive noise estimation and reduce the required number of pilot subcarriers, the distributed compressed sensing method is utilized based on the significant sparse correlation of impulsive noise. Additionally, an adaptive sparsity detection algorithm for measuring the sparsity of impulsive noise is introduced. The effectiveness of the proposed methods is comprehensively validated through simulation experiments demonstrating improvements in impulsive noise estimation, channel estimation, and output signal-to-noise ratio (SNR), with gains of at least 26.30 dB, 22.91 dB, and 11.05 dB, respectively, compared to existing algorithms. Moreover, sea trial experiments indicate an average output SNR gain exceeding 3.10 dB. The superior systems with higher data rates and more robustness significantly accelerate the development of UWA communication.