HARQ throughput enhancement using maximum likelihood block detection with recursive QR packet combining and M-algorithm for single-carrier MIMO

For achieving very high-speed and high quality packet transmission, the joint use of multi-input multi-output (MIMO) spatial multiplexing and hybrid automatic repeat request (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, we consider a single-carrier (SC) MIMO and propose a maximum likelihood block detection using recursive QR packet combing and M-algorithm called recursive QRM-MLBD. We will show, by computer simulation, the recursive QR packet combing provides a better throughput performance than the conventional bit-level log likelihood ratio (LLR) packet combining. We also compare the achievable throughput performance of proposed recursive QRM-MLBD to that of the frequency-domain detection based on the minimum mean square error criterion (MMSED).