Energy-Efficient Encoding by Measurement-Based Power Consumption Model for RIS-Assisted Communication Systems

Reconfigurable intelligent surfaces (RISs) with the capability of nearly passive beamforming, have recently sparked considerable interests. This paper presents an energy-efficient discrete phase encoding method for RIS-assisted communications, which utilizes a measurement-based RIS power consumption model and considers a trade-off between the power consumption and beamforming gain. Firstly, based on the beamforming gain and power consumption models, an energy-efficient encoding optimization problem under a quality-of-service constraint is formulated for RIS-assisted systems. Subsequently, inspired by the uniform phase quantization (UPQ), the non-uniform phase quantization (NUPQ) is proposed and explained. Following the guideline of NUPQ, a phase encoding method is proposed with a linear complexity, to effectively improve the RIS energy efficiency. Simulation results verify the more favorable performance of the proposed method in terms of the RIS power consumption and energy efficiency. Furthermore, a field trial at 35 GHz validates the application performance of the proposed method in reality.