Optimizing RIS-assisted Wireless Communication Systems with Non-Linear Energy Harvesting

Reconfigurable intelligent surfaces (RIS) or Intelli-gent reflecting surfaces (IRS) are synonyms to a highly disruptive technology being proposed for beyond 5G (B5G)/6G Wireless Communications due to its environment controllable, power saving and spectral efficient features. Internet-of- Things (loT) devices demand for longer battery life with considerable data rate. To address this concern, simultaneous wireless information and power transfer (SWIPT) is currently being explored in combination with RIS. In this paper, we consider a time-switching (TS) SWIPT architecture with non-linear energy harvesting (EH) at the loT node. The concerned base station provides information and energy concurrently to the loT node through RIS. We formulate EH maximization problem under various sets of constraints, which can be solved using the proposed iterative optimization algorithm following a divide-and-conquer methodology. Numerical evaluation confers that it is necessary to have a larger number of RIS elements to get maximum benefit in terms of EH.