DistributedHART: A Distributed Real Time Scheduling System for WirelessHART Networks

Industry 4.0 is a new industry trend which relies on data driven business model to set the productivity requirements of the cyber physical system. To meet this requirement, Industry 4.0 cyber physical systems need to be highly scalable, adaptive, real-time, and reliable. Recent successful industrial wireless standards such as WirelessHART appeared as a feasible approach for such cyber physical systems. For reliable and real-time communication in highly unreliable environments, they adopt a high degree of redundancy. While a high degree of redundancy is crucial to real-time control, it causes a huge waste of energy, bandwidth, and time under a centralized approach, and are therefore less suitable for scalability and handling network dynamics. To address these challenges, we propose DistributedHART - a distributed real-time scheduling system for WirelessHART networks. The essence of our approach is to adopt local (node-level) scheduling through a time window allocation among the nodes that allows each node to schedule its transmissions using a real-time scheduling policy locally and online. DistributedHART obviates the need of creating and disseminating a central global schedule in our approach, and thereby significantly reducing resource usage and enhancing the scalability. To our knowledge, it is the first distributed real-time multi-channel scheduler for WirelessHART. We have implemented DistributedHART and experimented on a 130-node testbed. Our testbed experiments as well as simulations show at least 85% less energy consumption in DistributedHART compared to existing centralized approach while ensuring similar schedulability.