Conservative Channel Reuse in Real-Time Industrial Wireless Sensor-Actuator Networks

Wireless Sensor-Actuator Networks (WSANs) are being adopted as an enabling technology for Industrial Internet of Things (IIoT) in process industries. Industrial applications impose stringent requirements in reliability and real-time performance on WSANs. To enhance reliability, industrial standards, such as WirelessHART, embrace Time Slotted Channel Hopping (TSCH) that integrates channel hopping and TDMA at the MAC layer. Within a network governed by a same gateway, WirelessHART prohibits channel reuse, i.e., concurrent transmissions in the same channel, to avoid interference between concurrent transmissions. Preventing channel reuse however negatively affects real-time performance. To meet the demand for both reliability and real-time performance by industrial applications, we propose a conservative channel reuse approach designed to enhance the real-time performance while limiting its impact on reliability in WSANs. In contrast to traditional channel reuse designed to optimize performance at the cost of reliability, our conservative approach introduces channel reuse only when needed to meet the timing constraints of flows. Finally, we present an algorithm to detect reliability degradation caused by channel reuse so that channels can be reassigned to further improve reliability. Experimental results based on two physical testbeds show that our approach significantly improves real-time performance while maintaining a high degree of reliability.