Frequency Domain Equalization Based Inter-Carrier Interference Mitigation of Underwater OFDM-MFSK-S2C Communication Scheme

Orthogonal frequency division multiplexing-multiple frequency shift keying (OFDM-MFSK) communication performance is limited by the frequency-selective fading of the underwater acoustic (UWA) channel and is strongly affected by narrowband interference. To address these problems, researchers in the field of radio communication combined OFDM-MFSK with the sweep-spread carrier scheme (OFDM-MFSK-S2C). In this paper, the OFDM-MFSK-S2C scheme is applied to the field of UWA communication and its performance is analyzed. The scheme transforms the frequency-selective fading due to multipath into shift accumulation of subcarriers in the frequency domain. Therefore, for the separation characteristics of the multipath, this paper proposes a linear equalizer based on the multipath separation structure in the frequency domain. It further mitigates the inter-carrier interference (ICI) caused by multipath. The simulation results demonstrate that compared with the OFDM-MFSK scheme, the performance of the new scheme is improved over multipath channels and narrowband interference channels. Meanwhile, the proposed equalizer can effectively mitigate ICI under multipath channels.