DiGS: Distributed Graph Routing and Scheduling for Industrial Wireless Sensor-Actuator Networks

Wireless Sensor-Actuator Networks (WSANs) technology is appealing for use in industrial IoT applications because it does not require wired infrastructure. Battery-powered wireless modules easily and inexpensively retrofit existing sensors and actuators in industrial facilities without running cabling for communication and power. IEEE 802.15.4 based WSANs operate at low-power and can be manufactured inexpensively, which makes them ideal where battery lifetime and costs are important. Almost a decade of real-world deployments of WirelessHART standard has demonstrated the feasibility of using its core techniques including reliable graph routing and Time Slotted Channel Hopping (TSCH) to achieve reliable low-power wireless communication in industrial facilities. Today we are facing the 4th Industrial Revolution as proclaimed by political statements related to the Industry 4.0 Initiative of the German Government. There exists an emerging demand for deploying a large number of field devices in an industrial facility and connecting them through a WSAN. However, a major limitation of current WSAN standards is their limited scalability due to their centralized routing and scheduling that enhance the predictability and visibility of network operations at the cost of scalability. This paper decentralizes the network management in WirelessHART and presents the first Distributed Graph routing and autonomous Scheduling (DiGS) solution that allows the field devices to compute their own graph routes and transmission schedules. Experimental results from two physical testbeds and a simulation study show our approaches can significantly improve the network reliability, latency, and energy efficiency under dynamics.