Understanding the Impact of Packet Size on the Energy Efficiency of LoRaWAN

LoRaWAN has become a flagship LPWAN technology, and one of the main connectivity alternatives for IoT devices. Since LoRaWAN was designed for low energy consumption, it is fundamental to understand its energy performance. In this paper, we study the impact of packet size on LoRaWAN device energy consumption per delivered data bit (EPB). By means of extensive simulations, we show that, when network performance is very high or very low, EPB decreases steadily with packet size; otherwise, EPB may show an "asymmetric U" shape as a function of packet size, with a minimum EPB value that is achieved for a medium packet size. We also provide detailed insights on the reasons that produce the observed behaviors.