Iterative multi-channel equalization and LDPC decoding for underwater acoustic coherent communications

Multi-Channel adaptive decision feedback equalizer (MC-ADFE) is a main method to overcome multi-path distortion and eliminate Inter-Symbol Interference (ISI) for underwater acoustic channel. LDPC codes are capacity achieving codes, which can provide considerable coding gain. In this paper, the turbo theory is applied to form iterative multi-channel adaptive decision feedback equalizer (MC-ADFE) and LDPC decoder. In iterative equalization and decoding algorithm (IED), the MC-ADFE and LDPC decoder exchange soft information in an iterative manner, which can enhance the equalizer performance using significant decoding gain. The simulation results show that proposed system scheme can improve the performance of equalizer and get considerable coding gain. So, the performance of underwater acoustic communication system can be improved greatly.