The Impact of LoRaWAN Relay Mode on IoT End Node Energy Consumption

The adoption of the LoRaWAN protocol in agriculture use-cases has grown in popularity due to its cost-effective deployment, long-range connectivity, and low-power requirements. However, the standard LoRaWAN faces several challenges, such as ensuring reliable communication with underground sensors in adverse environmental conditions. The recently released LoRaWAN relay feature enables LoRaWAN to extend the communication range and hence addresses some of the performance concerns of LoRaWAN with respect to low data rate and coverage. This paper offers a brief summary of the LoRaWAN relay feature, providing an overview of its functionality. We discuss the challenges and limitations associated with the relay implementation. In particular, we compare the energy consumption between a standard end device that utilizes Semtech®SX1276 radio chip and a relay-compliant end node based on a concrete example. From this, we observe that the relay mode considerably increases the energy consumption of end nodes transmitting with spreading factors 7 and 12 as compared to standard LoRaWAN. Depending on the actual coverage conditions, the benefit of increased network coverage may come at a considerable cost and therefore limit the possible applications of LoRaWAN relay.