How to Make Firmware Updates over LoRaWAN Possible

The requirements of embedded software management - due to concerns about security vulnerabilities or for feature updates in the Internet of Things (IoT) deployments - have raised the need for Firmware Updates Over The Air (FUOTA). With FUOTA's support, security updates, new functionalities, and optimization patches can be deployed with little human intervention to embedded devices over their lifetime. However, supporting FUOTA over one of the most promising IoT networking technologies, LoRaWAN, is not a straightforward task due to LoRaWAN's limitations that challenge bulk downlink data transfer such as a firmware image. Therefore, the LoRa Alliance has proposed new specifications to support multicast, fragmentation, and clock synchronization on top of LoRaWAN, which are essential features to enable efficient FUOTA. In this paper, we review these new specifications and evaluate the FUOTA process in order to quantify the impact of the different FUOTA parameters in terms of the firmware update time, the device's energy consumption, and the firmware update efficiency, showing different trade-offs among the parameters. For this, we developed FUOTASim, a simulation tool that allows us to determine the best FUOTA parameters.