Massive Wireless Energy Transfer: Enabling Sustainable IoT Towards 6G Era

TL;DR

This paper reviews recent advances in wireless energy transfer (WET) for powering massive IoT networks in the 6G era, discussing architectures, challenges, techniques, and future research directions.

Contribution

It provides a comprehensive overview of WET architectures, enablers, and strategies, highlighting the integration of beamforming, distributed systems, and CSI strategies for scalable IoT power solutions.

Findings

Combining DAS and EB enhances wireless power transfer efficiency.

Average CSI strategies are effective for powering many devices simultaneously.

CSI-free WET techniques are promising for ultra-low power IoT devices.

Abstract

Recent advances on wireless energy transfer (WET) make it a promising solution for powering future Internet of Things (IoT) devices enabled by the upcoming sixth generation (6G) era. The main architectures, challenges and techniques for efficient and scalable wireless powering are overviewed in this paper. Candidates enablers such as energy beamforming (EB), distributed antenna systems (DAS), advances on devices' hardware and programmable medium, new spectrum opportunities, resource scheduling and distributed ledger technology are outlined. Special emphasis is placed on discussing the suitability of channel state information (CSI)-limited/free strategies when powering simultaneously a massive number of devices. The benefits from combining DAS and EB, and from using average CSI whenever available, are numerically illustrated. The pros and cons of the state-of-the-art CSI-free WET techniques in ultra-low power setups are thoroughly revised, and some possible future enhancements are outlined. Finally, key research directions towards realizing WET-enabled massive IoT networks in the 6G era are identified and discussed in detail.