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Lookup NU author(s): Dr Sergey Mileiko, Connor Bramwell, Mohd Firdaus Hirman RitomORCiD, Dr Oktay CetinkayaORCiD, Dr Domenico Balsamo
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LoRaWAN, the MAC layer protocol built on top of LoRa modulation, adopts Adaptive Data Rate (ADR) to optimize communications by dynamically adjusting parameters like spreading factor (SF), transmitting power, and bandwidth based on signal quality metrics, e.g., signal-to-noise ratio (SNR). However, since energy harvesting (EH) IoT devices function only on the intervals of intermittent energy availability, the generic ADR mechanism has to be energy-aware to allow LoRaWAN operation under energy constraints. This expectedly introduces major challenges, such as preserving critical system information during power outages and managing the varying energy needs at run-time. To address these challenges, this paper introduces an energy management unit (EMU) meeting the ADR requirements based on the harvested energy whilst retaining critical information through the microcontroller unit (MCU) when no power is available. The proposed EMU dynamically selects the energy storage size and the operating voltage, which refers to the multiple operating points, to provide the amount of energy required for each task, e.g., LoRa transmission at the SF requested by the ADR. Considering the varying needs of IoT devices, this multiple operating points approach, compared to the conventional way of using one big storage for all tasks, avoids lengthened start-ups, and therefore approximates the operation to a battery-powered system. Experimental results demonstrate that the proposed design can retain the EMU operating points and enable intermittent LoRaWAN communications by managing the available energy at run-time.
Author(s): Mileiko S, Bramwell C, Ritom F, De Roure D, Cetinkaya O, Balsamo D
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: 11th International Workshop on Energy Harvesting & Energy-Neutral Sensing Systems (ENSsys'23)
Year of Conference: 2023
Pages: 23-29
Print publication date: 13/11/2023
Online publication date: 16/11/2023
Acceptance date: 10/11/2023
Publisher: Association for Computing Machinery
URL: https://doi.org/10.1145/3628353.3628541
DOI: 10.1145/3628353.3628541
