Iterative sparse channel estimation and decoding for underwater MIMO-OFDM

In this paper we propose a block-by-block iterative receiver for underwater MIMO-OFDM that couples channel estimation with MIMO detection and channel decoding. In particular, the channel estimator is based on a compressive sensing technique to exploit the channel sparsity, the MIMO detector consists of a hybrid use of successive interference cancellation and soft MMSE equalization, and the channel codes used are nonbinary LDPC codes. Various feedback strategies such as hard, soft, and thresholded symbol feedback are studied. We test the receiver performance using simulation and experimental data collected from the RACE08 and SPACE08 experiments. All iterative receivers show impressive gains over a non-iterative receiver.