A novel bit-level DS combining scheme for MIMO systems with HARQ

This paper proposes a novel bit-level combining scheme based on Dempster-Shafer (D-S) evidence theory, termed DS combining, for multiple-input multiple-output (MIMO) systems with hybrid-automatic-retransmission-request (HARQ) mechanism. The DS combining is assisted by the proposed DS detection for performance improvement. The focal-element-set (FES) characterizes the uncertainty contained in the decision statistics, and the corresponding basic-probability-assignment (BPA) of FES is the likelihood measure. The uncertainty can be counteracted by DS detection and further counteracted by DS combining, so more reliable decisions are achieved. Simulation results verify that the proposed combining scheme significantly outperforms its log-likelihood-ratio (LLR) combining counterpart with only moderate complexity increases.