A Scheduling Algorithm for Improving Scalability of LoRaWAN

In this paper, we propose a scheduling algorithm to connect a massive number of IoT devices in LoRaWAN. The proposed algorithm supports time-synchronized transmissions to mitigate the problem of scalability due to random channel access used in LoRaWAN. Our proposed algorithm schedules spreading factors, frequency channels, and timeslots for wireless links connecting end devices and gateways. Also, the group acknowledgement is employed to improve channel efficiency by aggregating acknowledgements of uplink transmissions received simultaneously from multiple end devices. We evaluate the performance of the proposed algorithm and compare it with the performance of ALOHA used for uplink transmissions in LoRaWAN. Our numerical results show that the proposed algorithm improves the connectivity of end devices over ALOHA. Compared to ALOHA, the proposed algorithm provides more than 60% increase in the number of end devices connected to a gateway, whereas more than 90% data messages originating from all end devices are delivered successfully.