Oversampled OFDM Detector for MIMO Underwater Acoustic Communications

In this paper, an oversampled orthogonal frequency division multiplexing (OFDM) detector is proposed for multiple-input multiple-output (MIMO) underwater acoustic (UWA) communications. With simple time-domain oversampling and frequency-domain signal processing, the new oversampled OFDM (OOFDM) detector can achieve multipath diversity that is unavailable in a conventional uncoded OFDM system, while maintaining the similar complexity as the conventional OFDM system. The new OOFDM detector can be directly applied to the received OFDM signals without changing the structure of the OFDM transmitter. The proposed MIMO OOFDM detector has been tested by field trial data collected in the SPACE08 experiment launched near Martha's Vineyard, Edgartown, MA, in 2008. Experimental results show that the oversampled OFDM detector outperforms the conventional OFDM detector, and an oversampling factor of 2 achieves the best tradeoff between the performance gain and the computational complexity.