Frequency-domain turbo detection for LDPC-coded single-carrier mimo underwater acoustic communications

This paper proposes a frequency-domain detection scheme for single-carrier multiple-input, multiple-output (MIMO) underwater acoustic (UWA) communication using low-density parity-check (LDPC) codes. The new scheme employs turbo equalization technology together with iterative decoding technique, leading to a double-layer turbo detection structure. In the outer-layer turbo equalization, a soft-decision frequency-domain equalizer (FDE) iteratively exchanges soft information with the soft-decision LDPC channel decoder. Within each outer-layer iteration, the LDPC decoder performs inner-layer iterative decoding with sum-product algorithm. The new scheme achieves excellent detection performance attributing to the double layers of iterative operation, which has been tested by experimental data measured in two undersea trials: WHOI09 and ACOMM09. Experimental results have demonstrated that it achieves consistently decent detection performance with different modulations, different symbol rates, and different transmission ranges.