Low-complexity layered BP-based detection and decoding for a NB-LDPC coded MIMO system

In this paper, the combination of a low-complexity Multiple-input Multiple-output based on belief propagation (MIMO-BP) detector with a Non-Binary Low-Density Parity-Check (NB-LDPC) decoder is investigated. Such detection and decoding algorithms can enable an equivalent representation based on a larger Joint Factor Graph (JFG). Shuffle schedule can therefore be used jointly and simultaneously on the detector and the decoder. Actions are undertaken at the detector, decoder and the iterative receiver levels in order to reduce overall complexity. Indeed, applying the proposed low-complexity BP-based detection greatly reduces the number of operations per iteration (divided by ten), with a negligible performance penalty. EXtrinsic Information Transfer (EXIT) charts enable to analyze the convergence behaviour of the proposed iterative receiver. This analysis is used to find the best set of parameters enabling a detection-decoding process with a performance closest to the full-complexity system.