Reconfigurable Intelligent Surface-Assisted Wireless Powered Sensing and Communication Networks

A novel idea of wireless powered sensing and communication networks (WPSCN) is proposed. Specifically, a multi-antenna transmitter utilizes a radar signal for sensing targets while enabling multiple Internet of Things (IoT) devices to harvest energy from the signal, each of which employs the collected energy to upload information to an access point (AP). We deploy a reconfigurable intelligent surface (RIS) to assist sensing and improve wireless energy transfer (WET) and wireless information transfer (WIT). This paper aims to maximize the weighted sum of the communication throughput and the beampattern gain by jointly designing the transmitter beamforming, transmission time scheduling and RIS phase shifts. We initially derive a closed-form expression of the optimal RIS phase shifts in the WIT phase. Then, an alternating optimization (AO) algorithm is proposed to solve the trade-off problem. Additionally, we introduce a low-complexity AO algorithm that derives the optimal solutions for transmitter beamforming, transmission time scheduling, and sensing/WET phase shift. Simulation results demonstrate the effectiveness of the proposed algorithms.