Toward Green 6G Networks: NOMA-Based Reconfigurable Intelligent Surfaces with Hybrid Acoustic–Magnetic Energy Harvesting

This work introduces a novel self-sustainable wireless communication architecture that combines RIS and NOMA with a hybrid acoustic–magnetic energy harvesting framework. The source node operates under strict energy constraints and is powered by harvesting ambient acoustic vibrations and surrounding magnetic fields, enabling autonomous transmission to multiple NOMA users. To enhance propagation conditions, an RIS is deployed to intelligently control the wireless channel by optimizing its phase response, thereby strengthening desired signals and suppressing interference.The performance of the proposed system is analytically characterized under the hybrid energy harvesting model. The derived expressions provide insight into the interaction between harvested energy dynamics, RIS configuration, and NOMA transmission. Simulation results confirm that the proposed RIS-NOMA architecture significantly outperforms conventional orthogonal and non-orthogonal access schemes in both spectral and energy efficiency. In addition, the hybrid harvesting mechanism ensures more stable energy availability, improving reliability in highly energy-constrained environments.