Abstract
Space-time trellis codes (STTCs) combine channel coding and multiple-input multiple-output (MIMO) techniques to provide coding and diversity gains for wireless communication systems. The decoding complexity is extremely high because of the high density of branch metric calculations. Thus, this study presents a state-purging mechanism based on the T-algorithm to reduce the computational complexity. In the proposed mechanism, an embedded code-aided (CA) signal-to-noise (SNR) estimator provides the SNR information to determine the optimal threshold based on the count of metric normalization. The state-purging mechanism greatly reduces the complexity of branch metric calculations and produces only negligible coding gain degradation. The fabricated 4×4 STTC MIMO detector using 90 nm 1P9M CMOS technology reduces 17.62%, 15.81%, and 13.45% power consumptions for QPSK, 8PSK, 16QAM modulations, respectively, when SNR is 20 dB.