Lightweight Timeslot Scheduling Through Periodicity Detection for Increased Scalability of LoRaWAN

Abstract

Massive Machine Type Communications is a wireless paradigm which focuses on traffic that is transmitted by a huge number of low cost, low power, infrequently transmitting devices. LoRaWAN, a Low Power Wide Area Network technology, is particularly suited to contribute to coverage of this form of traffic. In this work, we introduce a novel, lightweight timeslot scheduling scheme that supports the requirements for massive Machine Type Communications on LoRaWAN networks (based on traffic periodicity, and the multiple channels and quasiorthogonal data rates in LoRaWAN). Our novel approach does not require extended downlink transmissions from the gateways, and does not require time synchronisation between the devices and the LoRaWAN Network Server. We implement our scheme in a publicly available LoRaWAN ns-3 module. Our results show that the scheme doubles the number of frequently transmitting mMTC devices that can be handled by a single LoRaWAN gateway while providing the same level of performance in terms of successful packet deliveries, and maintaining a reasonable delay for mMTC use cases, without impacting the ability of the network to send downlink frames or acknowledge high priority packets. Our contribution is a novel approach to TDMA that is suited for mMTC networks.