Pilot-subcarrier based impulsive noise mitigation for underwater acoustic OFDM systems

Orthogonal frequency-division multiplexing (OFDM) technique has become a popular choice for underwater acoustic (UA) networks recently. Impulsive noise is one of the factors that limit the performance of this technique, and the mitigation of impulsive noise receives increasing attention in the UA communication community. In this paper, a pilot-based algorithm is proposed to mitigate the impact of impulsive noise. The proposed algorithm introduces a special OFDM block as preamble during which impulsive noise mitigation is performed using the null subcarriers and then the channel response is estimated using pilot subcarriers. By assuming that the channel is quasi-stationary, the proposed algorithm adopts the channel estimation result of the previous block to estimate and mitigate the impulsive noise of the current block. We apply the proposed algorithm to process the data collected during the experiment conducted in December 2015, in the estuary of the Swan River, Western Australia. The results show that the proposed approach is able to mitigate the impulsive noise for UA OFDM systems.