Complexity-efficient detection for MIMO relay networks

This paper provides the equivalent maximum likelihood (ML) detector at the destination of multi-branch dual-hop multiple-input multiple-output (MIMO) relay networks. Complexity-efficient detections by extending both the complexity-efficient sphere decoder (CSD) and the fixed complexity sphere decoder are proposed. Comparing to the direct link and the cooperative partial detection, our detection method based on the CSD shows the almost-fixed, reduced complexity at a negligible performance loss. Although detect-and-forward relaying is the main focus, this detection also performs well in amplify-and-forward relaying. The simulation results show that the CSD performs nearly optimal ML performance, while keeping the complexity of MIMO relay detection fixed and reduced, making this algorithm suitable for hardware implementation.