Improved LAS detector in the iterative large MIMO systems with LDPC codes

In this paper, low complexity iterative detection and decoding algorithms applied in large MIMO systems are considered. We propose an iterative scheme consists of likelihood ascent search (LAS) detection and low density parity check (LDPC) decoder in the uplink of large MIMO systems. During the iterative process, the check candidate set of LAS detector is decided by the feedback extrinsic information of the LDPC decoder. The feedback extrinsic information can be enlarged when the output codeword satisfies the parity-check equations, which can further improve the performance. Through simulation results we can see the proposed scheme achieves approximately 0.6dB gain compared with direct iterative scheme. When compared with MMSE-LDPC iterative scheme, the BER performance is only 0.2dB worse with the complexity much lower.