Overview of Hexagonal QAM Based Constellation Schemes and Applications for Index Modulation

This paper presents a comprehensive review of hexagonal QAM (HQAM) techniques that improve energy efficiency and spectral efficiency, and analyzes their impact on the currently widely used index modulation techniques. In particular, the integration of HQAM with advanced index modulation techniques such as spatial modulation (SM), quadrature spatial modulation (QSM) and media-based modulation (MBM) is discussed. It is shown that HQAM significantly reduces energy consumption during transmission by providing a more homogeneous symbol distribution compared to conventional square QAM structures. Analysis on Rayleigh fading channels reveals that HQAM, when combined with index modulation techniques, significantly improves energy savings and provides an optimal solution for systems with high data rates. Furthermore, BER performance comparisons show that the proposed HQAM-based schemes offer similar performance to conventional QAM modulation with index modulation techniques, but with superior energy efficiency. This indicates that HQAM is poised to play an important role in future wireless communication systems.