Soft feedback turbo equalization for underwater acoustic communications

In this paper, A low-complexity turbo detection scheme is proposed for single-carrier multiple-input multiple output (MIMO) underwater acoustic (UWA) communications that employs low-density parity-check (LDPC) channel coding. The proposed iterative soft feedback equalization (SFE) algorithm offers a novel approach to combating error propagation by utilizing the past soft decisions to mitigate inter-symbol interference. In addition, its computational complexity grows only linearly with the number of equalizer coefficients, compared to the quadratic complexity of minimum mean square error-based linear turbo equalizer. Performance of the proposed detection scheme is verified through experimental data collected in MACE10. Experimental results show that it provides robust detection and improved Bit Error Rate (BER) for MIMO UWA communications with different modulations schemes.