Desenvolvimento e avaliação de uma estação retransmissora para redes LoRaWAN

Abstract

The growing demand for connectivity in Internet of Things applications has driven research into devices with long-range and low powerconsumption,suchasLoRatechnologyandtheLoRaWAN protocol, which organizes network communication. Despite advancements, physical obstacles and infrastructure limitations still compromise coverage and communication reliability in challenging scenarios. In this context, the TS011 LoRaWAN Relay specification and the implementation of a repeater using the LoRa Basics Modem library present an alternative to expand network coverage, reduce communication failures, and enable the operation of end devices with lower transmission power. However, there is still a lack of experimental evaluations with firmware adhering to this specification in the literature. Therefore, the objective of this work is to experimentally evaluate the operation of a LoRaWAN repeater developed with the LoRa Basics Modem library, as well as to analyze the relationship between reliability and energy consumption. In the first experiment, the operation of the repeater with the standard LoRa Basics Modem firmware was evaluated, based on six experimental arrangements and different operating conditions. The results showed that the repeater extended the network range and improved the message delivery rate in areas where the gateway’s range was limited or nonexistent. In low-coverage scenarios, the repeater proved indispensable to the network architecture, although its dynamic activation required the end devices to be restarted to adapt to the new topology. In the second experiment, an energy consumption assessment was performed to verify whether adopting higher fixed spreading factors could be considered a viable compromise in the face of increased reliability. The results show that increasing the spreading factor increases communication reliability and also energy consumption during transmission. However, this increase does not significantly impact total energy consumption, as the greatest energy cost is in the continuous operation of the device over time. In the third experiment, a spreading factor supervisor mechanism was incorporated into the LoRa Basics Modem firmware, designed to operate with higher fixed values and prioritize communication reliability. Compared to standard firmware, the supervisory mechanism increased message delivery by 92.8 percentage points, in addition to reducing the end device’s power consumption by eliminating the need to keep adaptive data rate mode active.