Hexagonal Quadrature Amplitude Modulation Aided Spatial Modulation

Abstract

In this study, a new multiple-input multiple-output (MIMO) transmission scheme with energy-efficiency is proposed by combining spatial modulation (SM) and energy-efficient hexagonal quadrature amplitude modulation (HQAM) constellation scheme, briefly called HQAM-SM. HQAM optimizes the assignment of code words to points in the form of a hexagonal constellation to minimize the average Hamming distance. This arrangement always uses energy more effectively than conventional quadrature amplitude modulation (QAM) and performs almost the same performance as QAM at higher SNRs. Besides, as it is known, SM is a promising MIMO technique for next-generation communication techniques, which carry data both with antenna and conventionally modulated symbols. In this study, a more energy-efficient system is proposed compared to the conventional SM, in which SM will carry data with HQAM instead of carrying data with conventional modulated symbols in addition to antenna index. The performance analysis of the proposed HQAM-SM system was performed on Rayleigh fading channels.