Pilot Assisted MIMO OFDM-IM Design for Doubly Selective Underwater Acoustic Systems

This paper presents a MIMO-based orthogonal frequency division multiplexing-index modulation (OFDM-IM) communication system design for underwater acoustic systems. The proposed multiple-input multiple-output (MIMO)-OFDM-IM utilizes comb type pilot subcarriers to assist the receiver with the dilemmas arise by the time-varying underwater acoustic channels. In addition, the estimated channel supports the maximum likelihood detector in the estimation of the active subcarriers. The performance of the proposed design is shown via computer simulations using synthetic underwater acoustic channels. The Monte Carlo results show that the symbol error rate (SER) of the proposed approach outperforms the classical MIMO-OFDM approach.