A Low-Complexity Horizontal Layering Detection Algorithm for θ-QAM

Parametric quadrature amplitude modulation ($\theta$ QAM) has gradually gained attention because of its flexible adaptive structure, which is due to the change of angle $\theta$ between constellation points. In this correspondence, we develop a novel detection method called horizontal layered detection (HLD) for M-ary $\theta$-QAM. Based on maximum likelihood estimation, HLD divides the decision region to simplify the detection process. Compared to traditional detection methods, such as maximum likelihood detection (MLD), HLD can achieve the same detection accuracy with significantly lower computational complexity. The simulation results validate the performance advantages of the detection of M-ary $\theta$-QAM over existing methods. Specifically, the detection speed of M-ary $\theta$-QAM can be improved about 10 times.