Sustainable radio frequency wireless energy transfer for massive Internet of Things
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
L5, Linnanmaa campus
Topic of the dissertation
Sustainable radio frequency wireless energy transfer for massive Internet of Things
Doctoral candidate
Master of Science (Technology) Osmel Martinez Rosabal
Faculty and unit
University of Oulu Graduate School, Faculty of Information Technology and Electrical Engineering, CWC-Radio technologies
Subject of study
Communications Engineering
Opponent
Professor Liesbet Van der Perre, KU Leuven
Custos
Associate professor Hirley Alves, University of Oulu
Sustainable wireless charging solutions for everyday smart devices
Sustainable radio frequency (RF) wireless energy transfer (WET) is a promising solution for powering large-scale Internet of Things (IoT) ecosystems, as overcoming the limitations of traditional battery-powered devices in terms of maintenance, scalability, and environmental impact. Although energy-saving techniques can prolong the operation of devices, they are limited by the small battery capacities that IoT devices can typically accommodate. In this context, RF-WET serves as a complementary technology by enabling continuous, contactless power delivery using so-called power beacons (PBs), helping to sustain device operation and thereby reducing frequent maintenance. This thesis develops efficient charging strategies to support sustainable RF-WET.
We begin by identifying key challenges and research directions towards realizing sustainable RF-WET systems. Then, we study PBs deployment strategies that exploit knowledge of device locations and battery states to meet devices' energy outage constraints with minimal transmit power. The impact of ambient energy source (\textit{e.g.}, sunlight, wind) availability in enabling self-sufficient PBs is also examined. To improve efficiency, we design a low-complexity charging protocol that leverages system non-linearities and explore both time- and space-division strategies to minimize energy consumption.
Scalable PB architectures are also investigated, with a focus on power consumption and electromagnetic field exposure of PBs equipped with reconfigurable surfaces. We analyze how the PB geometry, operating frequency, and device power needs influence both PB's power consumption and power density in the vicinity of the served device. Finally, we propose a power-minimization optimization framework for PBs with movable antennas that overcomes the intrinsic interdependency of the system variables. We evaluate key factors affecting the power consumption and shed some light on how channel propagation conditions are influenced by both the number of antennas and the distribution of devices in the network.
All in all, the proposed techniques demonstrate potential to advance sustainable RF-WET as a long-term solution for meeting current and future charging demands of IoT networks. It is our expectation that the novel ideas presented in this thesis will contribute to shaping the development and implementation of next-generation sustainable WET technologies.
We begin by identifying key challenges and research directions towards realizing sustainable RF-WET systems. Then, we study PBs deployment strategies that exploit knowledge of device locations and battery states to meet devices' energy outage constraints with minimal transmit power. The impact of ambient energy source (\textit{e.g.}, sunlight, wind) availability in enabling self-sufficient PBs is also examined. To improve efficiency, we design a low-complexity charging protocol that leverages system non-linearities and explore both time- and space-division strategies to minimize energy consumption.
Scalable PB architectures are also investigated, with a focus on power consumption and electromagnetic field exposure of PBs equipped with reconfigurable surfaces. We analyze how the PB geometry, operating frequency, and device power needs influence both PB's power consumption and power density in the vicinity of the served device. Finally, we propose a power-minimization optimization framework for PBs with movable antennas that overcomes the intrinsic interdependency of the system variables. We evaluate key factors affecting the power consumption and shed some light on how channel propagation conditions are influenced by both the number of antennas and the distribution of devices in the network.
All in all, the proposed techniques demonstrate potential to advance sustainable RF-WET as a long-term solution for meeting current and future charging demands of IoT networks. It is our expectation that the novel ideas presented in this thesis will contribute to shaping the development and implementation of next-generation sustainable WET technologies.
Last updated: 1.9.2025