Low-complexity turbo detection for single-carrier low-density parity-check-coded multiple-input multiple-output underwater acoustic communications

摘要

A low-complexity turbo detection scheme is proposed for single-carrier multiple-input multiple-output (MIMO) underwater acoustic (UWA) communications using low-density parity-check (LDPC) channel coding. The low complexity of the proposed detection algorithm is achieved in two aspects: first, the frequency-domain equalization technique is adopted, and it maintains a low complexity irrespective of the highly dispersive UWA channels; second, the computation of the soft equalizer output, in the form of extrinsic log-likelihood ratio, is performed with an approximating method, which further reduces the complexity. Moreover, attributed to the LDPC decoding, the turbo detection converges within only a few iterations. The proposed turbo detection scheme has been used for processing real-world data collected in two different undersea trials: WHOI09 and ACOMM09. Experimental results show that it provides robust detection for MIMO UWA communications with different modulations and different symbol rates, at different transmission ranges.