A Low Complexity Loglikelihood Ratio Scheme in Coded Multiple-Input Multiple-Output Systems

The higher data rate in coded MIMO systems needs higher performance and lower computational complexity. This paper proposes a method to improve the performance and reduce the computational complexity in coded MIMO system, such as IEEE 802.11ac. The proposed scheme based on log likelihood ratio with QRM-MLD (QRM-MLD-LLR) needs to expand the estimated channel matrix H by MMSE scheme firstly, and use the partial constellations set S to replace the all constellations set C to reduce the computational complexity by the MMSE-SIC method secondly. Simulation results show that the proposed scheme with expanding H by MMSE can obtain better performance than non-expanding H, the proposed scheme can reduce more than 70% computational complexity but keep only 0.5dB performance loss.