Reduced tree-search, heuristic and linear decoupler low-complexity MIMO detectors

Since the optimal detector for coded and even uncoded multiple-input-multiple-output (MIMO) antenna systems results too complex when the number of antennas and/or the modulation order index increases, strictly low-complexity detection schemes are considered, aiming to achieve promising performance times complexity trade-off. Under the same throughput basis, this work analyzes some capacity-approaching heuristic and reduced tree-search MIMO detection algorithms, combining simple linear decouplers, local search detectors, particle swarm intelligence (PSO) concepts and parallel short low density parity check codes (LDPC), suitable to uncoded as well to MIMO channel coding. For uncoded MIMO systems, low-complexity PSO approach showed to reach efficiently MIMO near-capacity for any number of transmit and receive antennas configuration, while simple linear decoupler detectors for QPSK modulation with short LDPC coding achieve reasonable performance only for n_R ges n_T condition.