Pible: Battery-Free Mote for Perpetual Indoor BLE Applications
This work addresses the battery replacement problem for large-scale indoor sensor deployments by providing a practical, off-the-shelf battery-free solution with adaptive energy management.
Pible is a battery-free BLE sensor node that harvests ambient light to enable perpetual indoor sensing. A 20-node, 15-day deployment demonstrated feasible smart building applications with a predictive algorithm adapting to lighting conditions to maximize lifetime and quality of service.
Smart building applications require a large-scale deployment of sensors distributed across the environment. Recent innovations in smart environments are driven by wireless networked sensors as they are easy to deploy. However, replacing these batteries at scale is a non-trivial, labor-intensive task. Energy harvesting has emerged as a potential solution to avoid battery replacement but requires compromises such as application specific design, simplified communication protocol or reduced quality of service. We explore the design space of battery-free sensor nodes using commercial off the shelf components, and present Pible: a Perpetual Indoor BLE sensor node that leverages ambient light and can support numerous smart building applications. We analyze node-lifetime, quality of service and light availability trade-offs and present a predictive algorithm that adapts to changing lighting conditions to maximize node lifetime and application quality of service. Using a 20 node, 15-day deployment in a real building under varying lighting conditions, we show feasible applications that can be implemented using Pible and the boundary conditions under which they can fail.