FreeBeacon: Efficient Communication and Data Aggregation in Battery-Free IoT

To improve sustainability, Internet-of-Things (IoT) is increasingly adopting battery-free devices powered by ambient energy scavenged from the environment. The unpredictable availability of ambient energy leads to device intermittency, bringing critical challenges to device communication and related fundamental operations like data aggregation. We propose FreeBeacon, a novel scheme for efficient communication and data aggregation in battery-free IoT. We argue that the communication challenge between battery-free devices originates from the complete uncertainty of the environment. FreeBeacon is built on the insight that by introducing just a small degree of certainty into the system, the communication problem can be largely simplified. To this end, FreeBeacon first introduces a small number of battery-powered devices as beacons for battery-free devices. Then, FreeBeacon features protocols for battery-free devices to achieve interaction with the beacon and to perform communication efficiently following customized schedules that implement different data aggregation schemes while achieving resilience. We evaluate FreeBeacon with extensive prototype-based experiments and simulation studies. Results show that FreeBeacon can consistently achieve an order of magnitude data aggregation efficiency when compared with the state-of-the-art approaches.