Soft quasi-maximum-likelihood detection for multiple-antenna wireless channels
IEEE Transactions on Signal Processing
A QRD-M/Kalman filter-based detection and channel estimation algorithm for MIMO-OFDM systems
IEEE Transactions on Wireless Communications
Bit-interleaved coded modulation
IEEE Transactions on Information Theory
Closest point search in lattices
IEEE Transactions on Information Theory
The golden code: a 2×2 full-rate space-time code with nonvanishing determinants
IEEE Transactions on Information Theory
Adaptive control of surviving symbol replica candidates in QRM-MLD for OFDM MIMO multiplexing
IEEE Journal on Selected Areas in Communications
IEEE Journal on Selected Areas in Communications
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This paper proposes a rotation and scaling based transformation method to simplify the (quasi-)maximum-likelihood (ML) detectors (such as QRD-M, sphere decoding (SD), etc.) for the square quadrature amplitude modulation (S-QAM) modulated multiple-input and multiple-output (MIMO) systems with no performance degradation. The key idea of the simplification is to utilize the symmetric shape of the S-QAM constellation so that after rotation and scaling, real multiplication and addition with certain constellation points in symbol replica generation simply transform into bit shifting or even vanish. As an illustrative example, the QRD-M detector is employed in this work. By using the proposed method, the number of real multiplications of the symbol replica generation required for the QRD-M detector is reduced by 50% and 25% for 4-QAM and 16-QAM, respectively. The numbers of real addition reduction is twice the amount of multiplication. The underlying principle of the proposed rotation and scaling transformation can be straightforwardly extended to amplitude and phase-shift keying (APSK) modulated MIMO systems employing the QRD-M, SD, list sequential sphere decoder (LISS), list sphere decoding (LSD), and the full ML detectors.