Low-complexity iterative detection and decoding in finite geometry LDPC-coded MIMO systems

This paper presents a low-complexity iterative joint detection and decoding algorithm for finite geometry-low density parity check (FG-LDPC) coded multiple-input multiple-output (MIMO) systems, in which the MIMO channel detector and the FG-LDPC decoder iteratively exchange soft information. The key to the simplicity of the algorithm is the use of a bit flipping-based decoder for FG-LDPC code. An important issue addressed here is the generation of soft information from the binary outputs of the bit-flipping decoder to be fed back to the MIMO detector. Simulation results show that the proposed joint detection and decoding algorithm achieves a substantial reduction in decoding error probability compared to a cascaded detector and a decoder. We also compare the performance with belief-propagation (BP) based detector-decoders which are significantly more complex. The new algorithm provides a practical approach to joint detection and decoding of popular FG-LDPC codes in a MIMO system, a task which is computationally unmanageable with a BP algorithm.