High-order Direct Antenna Modulation via Passive Reconfigurable Intelligent Surface

Direct antenna modulation (DAM) enhances spectral efficiency and simplifies transmitter design, benefiting the sixth generation (6G) communications and Internet of Things (IoT) network. However, practical implementation faces challenges, including antenna design and integration with advanced modulation schemes. Reconfigurable intelligent surfaces (RIS) offer a promising solution by dynamical manipulation of incident electromagnetic waves. This paper introduces a modified G-S algorithm for low-complexity implementation of high-order quadrature amplitude modulation (QAM) and high-order amplitude phase shift keying (APSK) via RIS. The algorithm reduces computational overhead and enables efficient modulation, enhancing system performance and supporting high data rates. This advancement bridges the gap between theoretical feasibility and practical deployment, positioning DAM with RIS as a key technology for future 6G wireless networks and IoT applications.