No Batteries Needed: Providing Physical Context with Energy-Harvesting Beacons

Battery-powered digital beacons have played a significant role in shrinking the gap between physical and digital world. At the same time, ubiquitous sensing encourages tiny, unobtrusive, energy-harvesting devices to eliminate the limited lifetime of battery-powered devices. In this paper, we design a new fire-and-forget room number broadcaster beacon to investigate the feasibility and performance of such a design point. We study how several factors including different deployment spaces, the storage capacity of the harvester, indoor light intensity levels, and spatial position of the receiver impact the performance in three real-world deployments. We find that the 95th percentile of inter-packet reception time is 35 s or less in a lab space with exposure to sunlight and indoor lights, 29 s or less in an industrial plant with indoor lights, and 405 s or more in office rooms. With strategic beacon placement and a light intensity level of only 390 lx, performance can be improved by 61%. We believe that these results will help guide future energy-harvesting beacon deployments. We also outline possible improvements for future energy-harvesting beacon designs.