Multifocus Techniques for Reconfigurable Intelligent Surface-Aided Wireless Power Transfer: Theory to Experiment

Recently, reconfigurable intelligent surface (RIS) with passive beamforming capability is emerging as a potential technology for wireless power transfer (WPT) applications thanks to its cost-effective and energy-efficient features. This work studies multifocus techniques for RIS-aided WPT systems to...

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Bibliographic Details
Published in:IEEE internet of things journal 2022-09, Vol.9 (18), p.17157-17171
Main Authors: Tran, Nguyen Minh, Amri, Muhammad Miftahul, Park, Je Hyeon, Kim, Dong In, Choi, Kae Won
Format: Article
Language:English
Subjects:
Algorithms
Antenna arrays
Beamforming
Channel estimation
Energy harvesting
Focusing
Fresnel reflection
Fresnel zones
Internet of Things
Phased arrays
Power management
Receivers
reconfigurable intelligent surface (RIS)
Reconfigurable intelligent surfaces
Reflection
Unit cell
wireless power transfer (WPT)
Wireless power transmission
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Summary:Recently, reconfigurable intelligent surface (RIS) with passive beamforming capability is emerging as a potential technology for wireless power transfer (WPT) applications thanks to its cost-effective and energy-efficient features. This work studies multifocus techniques for RIS-aided WPT systems to simultaneously and adaptively charge multiple Internet of Things (IoT) devices in the Fresnel zone. In particular, we propose three multifocus methods, which are pattern addition (PA), random unit cell interleaving (RUI), and RIS tile division (RTD), for enabling multifocus RIS-aided WPT applications. We elaborate the algorithms for computing the RIS reflection phases for all methods. The proposed methods can balance the power levels of beams focused on multiple receivers by controlling weight factors. Furthermore, we have implemented a real-life RIS-aided WPT testbed to verify these proposed methods. The system consists of a phased antenna array transmitter, two receivers, and a 1-bit RIS with 512 unit cells. The WPT experiments have been performed in several test scenarios to show the effectiveness of the proposed techniques. The experiment results demonstrate that the proposed schemes effectively generate multiple focusing beams with adjustable power levels toward the desired receivers.
ISSN:2327-4662
2327-4662
DOI:10.1109/JIOT.2022.3195948