Ultra-Low-Power Over-the-Air-Update in secure LoRaWAN networks

Firmware updates are essential during the lifetime of an End Device (ED) for reasons that go from adding new functionalities to fixing security vulnerabilities. In the Internet of Things (IoT) deployments, the emergence of Low-Power Wide-Area Network (LPWAN) has introduced a new family of EDs that operate at long range with strong energy constraints. However, enabling Firmware Update Over-the-Air (FUOTA) capabilities on one of the most promising LPWAN communication technology that is LoRaWAN is not a straightforward task due to its limitations. Moreover the idea of having to transmit and process the huge amount of data that represents a firmware image does not seem compatible with the ultra-low-power requirements of an ED that is expected to run for a decade. Although the LoRa Alliance provided mechanisms to enable efficient FUOTA on Long Range Wide-Area Network (LoRaWAN), true multicast FUOTA is not yet supported by ChirpStack, the most used LoRaWAN open-source server stack, which makes it unfit for high-scale deployments. In this work, we propose a new firmware update server that runs along ChirpStack with the objective of handling differentiated FUOTA in a true multicast session and studying the required energy. Therefore, a dedicated test platform working on an energy harvesting technology is designed to validate the FUOTA process on an ultra-low-power real-life scenario. The chosen use-case is a Wireless Sensor Network (WSN) node for audio monitoring of forest ecosystems with the constraint of average power consumption of 10mW . The result of this development is that the FUOTA process of a differentiated firmware image of 15kB takes about 5 minutes and only needs 14 minutes to recover.