Studying Slot Assignment for Multi-Gateway Time Scheduled Channel Access in LoRaWan

LoRaWAN stands out as one of the fastest growing Internet of Things access networks, thanks to its extensive coverage and operation within the license-free ISM band. This feature enables individuals to easily establish wireless access for their devices. However, a notable drawback of LoRaWAN is its unregulated channel access, which can lead collisions and data loss. While scheduled MAC approaches theoretically offer a solution to such collisions and aim to enhance the reliability of LoRaWan, their real-world applicability, particularly in scenarios involving multiple gateways, remains unexplored. Consequently, we have devised a slot assignment strategy tailored for LoRaWANs with multiple gateways and demonstrate its effectiveness in large deployments across various cities worldwide. The chromatic number as a graph metric of the communication network can predict its suitability for supporting scheduled MAC operation. Additionally, we have developed a methodology to optimize gateway placement based on slot assignment, thereby reducing the number of gateways needed for a given network.