Realization of Wireless Power and Information Coexistence Through Reconfigurable Intelligent Surface: A Practical Approach With Experimental Validation

To enable high-tech lifestyles in the near future, trillions of connected low-power internet of things (IoT) devices should perpetually operate to meet the high-demand requirements of the users. Simultaneous wireless information and power transfer (SWIPT) is an indispensable technology for guaranteeing the endurable operation of massive IoT devices. Reconfigurable intelligent surface (RIS) is currently emerging as a cost-effective and energy-efficient solution for controlling wireless communication environments to enhance the quality of service. In this paper, we propose an efficient beam-sharing algorithm (BSA) designed for SWIPT systems that incorporate RIS to realize the coexistence of wireless power and information. The considered RIS-assisted SWIPT system consists of one RIS, one data transmitter (DTx), one power transmitter (PTx), one data user (DU), and one power user (PU). Since the required power for the power transfer is radically higher than that for the information transmission, the high power signal leaked from the PTx can cause fatal damage to data transmission and sensitive electronic components (e.g., LNA) integrated with DU. Hence, we primarily aim to maximize the desired power transfer from PTx to PU while minimizing the leakage power (i.e., interference) delivered to the DU. Additionally, the algorithm maximizes the quality of the information signal transmitted from DTx to DU. We then develop a simulator to verify the effectiveness of the proposed algorithm. We have investigated the performance of the proposed BSA algorithm with various quantization phase shifts (i.e., 1-bit, 2-bit, 3-bit, and continuous phase). A suppression ranging between 15 dB and 38 dB is witnessed in all simulation scenarios, while the DTx-DU power and PTx-PU power are simultaneously maximized in the simulated scenario. For further confirmation, we have built a real-life RIS-assisted SWIPT testbed and validated the proposed BSA algorithm. Experimental results indicate that the proposed BSA algorithm successfully delivers the maximum power/signal from PTx/DTx to PU/DU while limiting the interference signal sent by PTx to the DU to ensure robust and reliable data transmission.