Time-Switching and Phase-Shifting Control for RIS-Assisted SWIPT Communications
Wael Jaafar, Lina Bariah, Sami Muhaidat, Halim Yanıkömeroğlu
Abstract
We investigate here a reconfigurable intelligent surface (RIS)-assisted simultaneous wireless information and power transfer (SWIPT) communication between a gateway and an Internet-of-Things (IoT) device, where both RIS and IoT device need to harvest energy prior to communication. Within this context, we study our system for two operations, namely switching from energy harvesting to data transmission and RIS phase-shifting to ensure energy harvesting and to maximize the data rate at the IoT device. We consider the generalized non-orthogonal spectrum-sharing (NOSS) scenario with co-channel interference and the potential presence of miscellaneous power sources. The formulated non-convex problem is solved using a sequential approach, where the RIS time-switching is determined first. Then, depending on the environment conditions, the IoT device’s time switching and phase-shifting configurations for energy harvesting and data transmission are concurrently optimized. Numerical results provide several insights for the design of RIS-assisted SWIPT communications.