Real-Time Communication over LoRa Networks

Today, industrial Internet of Things (IIoT) are emerging in large-scale and wide-area applications (e.g., oil-field management). Traditional wireless solutions for industrial automation depend on short-range wireless technologies (WirelessHART, ISA100.11a), posing a big challenge to support the scale of today's IIoT. To address this limitation, we propose to adopt LoRa, a prominent low-power wide-area network technology, for industrial automation. Adopting LoRa for industrial automation poses some unique challenges. The fundamental building blocks of any industrial automation system are feedback control loops that largely rely on real-time communication. LoRa usually adopts a simple protocol based on ALOHA with no collision avoidance to minimize energy consumption which is less suitable for real-time communication. Existing real-time protocols for short-range technologies cannot be applied to a LoRa network due to its unique characteristics such as asymmetry between downlink and the uplink spectrum, predefined modes (class) of operation, and concurrent reception through orthogonal spreading factors. In this paper, we address these challenges and propose RTPL- a Real-Time communication Protocol for LoRa networks. RTPL is a low-overhead and conflict-free communication protocol allowing autonomous real-time communication of low-energy devices and exploits LoRa's capability of parallel communication. We implement our approach on LoRa devices and evaluate through both physical experiments and large scale simulations. All results show that RTPL achieves on average 75% improvement in real-time performance without sacrificing throughput or energy compared to traditional LoRa.