Run-time Energy and Time Management for Intermittent LoRaWAN Communications

Mileiko, S; Ritom, F; Shafik, R; Yakovlev, A; Balsamo, D

doi:10.1109/SAS60918.2024.10636450

Run-time Energy and Time Management for Intermittent LoRaWAN Communications

Lookup NU author(s): Dr Sergey Mileiko, Professor Rishad Shafik, Professor Alex Yakovlev, Dr Domenico Balsamo

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Abstract

Intermittent computing, utilising non-volatile memory (NVM) to maintain system state during power outages, addresses the unpredictability of energy harvesting (EH) in Internet of Things (IoT) systems. However, challenges persist, notably in ensuring energy-aware task-based operations and accurate timekeeping during system shutdowns, which impede real-time data collection. To address this, the paper presents an energy and time management unit (ETMU) for intermittent systems, which facilitates task-based operations and timekeeping capabilities using multi-harvest energy sources. This ETMU adjusts energy storage and operating voltage at run-time, meeting the energy needs of specific tasks and startup times while preserving crucial system information during power outages. Furthermore, this ETMU incorporates an ultra-low power real-time clock (RTC), ensuring independent and accurate timekeeping during system power outages.The proposed ETMU is integrated into an intermittent system designed for ultrasonic water flow measurements to demonstrate its functionality. This system incorporates three energy harvesters and utilizes the LoRaWAN communication protocol for data transmission and time synchronization. Experimental results demonstrate the efficient management of intermittent LoRaWAN communications and precise timekeeping for data collection.