Time Synchronization and Packet Scheduling for Satellite LoRaWAN Networks

The integration of Satellites and Internet of Things (IoT) networks offers a promising solution for enabling connectivity in remote and hard-to-reach areas, where consistent access to the internet and reliable power sources remains a significant challenge. Among IoT technologies, the LoRa modulation scheme and LoRaWAN protocol have been chosen for their low power consumption, Long-Range communication capabilities, and cost-effectiveness, making them suitable for such environments. However, these IoT networks still require intermittent internet access, which can be efficiently provided by satellites passing over these regions multiple times per day. This introduces the need for precise satellite orbit tracking to manage network availability effectively. During each satellite pass, a large number of devices fall within the satellite's coverage area, leading to potential packet collisions and communication failures. Consequently, this situation demands advanced time synchronization and packet scheduling techniques to optimize performance and ensure reliable network operation. To address these challenges, this thesis introduces two novel methods: REACT for LoRaWAN time synchronization and SALSA for LoRaWAN packet scheduling. REACT ensures that LoRaWAN devices operations are synchronized with satellite visibility windows, improving the overall network performance. SALSA is designed to efficiently manage transmission times, thereby reducing packet collision rates and enhancing communication reliability. These methods have been rigorously evaluated using first via a simulation environment, and then, a testbed, for implementing a Proof of Concept (PoC). The results demonstrate that REACT and SALSA perfectly operate to integrate Terrestrial LoRaWAN networks with Satellites, ensuring the required reliability and scalability. These contributions provide practical solutions to existing limitations in the field of satellite IoT, paving the way for the effective implementation of integrated LoRaWAN satellite technology, totally agnostic to the possible application scenarios.