Impulsive Noise Suppression and Concatenated Code for OFDM Underwater Acoustic Communications

Underwater acoustic (UWA) information transmission is vulnerable to the interference of impulsive noise, which has short duration, high energy and random occurrence, decreasing the reliability of the orthogonal frequency-division multiplexing (OFDM) systems seriously. In this paper, we introduce the symmetric alpha stable (SαS) distribution to model the underwater impulsive noise firstly, and verifies the accuracy by measured noise data. For strong impulsive interference, an adaptive window median filter algorithm based on Chebyshev inequality (AWMF-C) is proposed, which applies the Chebyshev inequality twice to filter out the impulses and designs an adaptive window median filter to suppress them. Secondly, the serial concatenated code with RS code as outer code and interleaver are applied to suppress the residual impulsive interference further. Simulation results show that the proposed algorithm can suppress impulsive noise effectively, and the concatenated coding system given in this paper can further reduce the bit error rate (BER) of the communications system under impulsive noise background.