Adaptive Tree Search Detection With Variable Path Expansion Based on Gram-Schmidt Orthogonalization in MIMO Systems
This paper proposes new adaptive tree search detection with variable path expansion based on Gram-Schmidt (GS) Orthogonalization (GSO) in MIMO systems. The authors adopt the GSO procedure to reduce the channel matrix instead of the QR-decomposition in the conventional QRM-MLD. This detection scheme combined the GSO reduction with the M-algorithm, what they call GSM-MLD, can achieve near-ML performance as the conventional QRM-MLD. The proposed detection method is a breadth-first algorithm and performs the adaptive tree search with variable path expansion in the GSM-MLD. In this paper, they introduce a path metric ratio function to evaluate the reliability for all the survived branches. The survived but lower reliable branches adopt parts of the constellation points as the candidates into the next detection layer.