Reduced‐complexity performance‐lossless (quasi‐)maximum‐likelihood detectors for S‐QAM modulated MIMO systems

Proposed is a simplified branch metric calculation method for the (quasi‐)maximum‐likelihood (ML) detector for square quadrature amplitude modulation (S‐QAM) aided multiple‐input and multiple‐output (MIMO) multiplexing systems while retaining identical performance to the respective one. The key idea of the proposed method is to exploit the geometric property of the S‐QAM constellation, so that the branch metric calculation for all the constellation points can be calculated in an incremental way from any constellation point mainly through addition and bit‐shift, thus significantly reducing the computational complexity of the ML detector.