Self-Sustainable RIS Aided Wireless Power Transfer Scheme

This paper investigates the potential advantages of applying reconfigurable intelligent surface (RIS) in the wireless power transfer (WPT) system and designs an efficient RIS-aided WPT scheme. First, we propose an independent beamforming algorithm. Compared to the existing joint beamforming, the proposed scheme achieves the same performance but is practically much more convenient. Second, we propose an absorb-then-reflect power transfer scheme so that the RIS-aided WPT system can be self-sustainable without external energy supply. Third, we analyze the WPT efficiency of the proposed scheme and derive the minimum required scale of the RIS elements to guarantee a performance gain over the traditional WPT system. Next, we consider the multi-user scenario, and propose power allocation schemes to maximize the energy utility. Finally, the effectiveness of the proposed RIS-aided WPT scheme is verified by simulation results.