Before revision:  In this paper, we overview the main architectures, challenges and techniques for efficient wireless powering. We emphasize on the suitability of Channel State Information (CSI) -free strategies when powering simultaneously a massive number of devices.
After revision:  In this paper, we overview 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) -free strategies when powering simultaneously a massive number of devices.