A Novel Low-Complexity Bitwise Detection Scheme for SIMO Systems

The recent evolution of various wireless techniques has paved the way for a remarkable evolution in wireless networks. Nonetheless, the main drawback of some cutting-edge techniques is the complex detection at the receiver by implementing the legacy maximum likelihood (MLi) scheme for signal demodulation. In this letter, a novel less complex detector is proposed based on performing a bitwise detection. The proposed scheme aims to reduce the received signal constellation search space by transforming the MLi-based detection to a search operation in a constructed binary constellation tree, resulting in a lower number of constellation points used for comparison. The proposed scheme is first introduced for single-input single-output (SISO) systems and then generalized for single-input multiple-output (SIMO) systems. The obtained results, backed up by Monte Carlo simulations, show that the proposed scheme manifests an identical performance as the optimal MLi scheme with a logarithmic complexity in terms of the modulation order compared to a linear one for the benchmark MLi one. Furthermore, closed-form expressions for the bit error probability are derived for the M-ary phase shift keying (PSK) modulation with $M=4$ and 8 (QPSK and 8-PSK) modulation schemes.