Detecting communication blackout in industrial Wireless Sensor Networks

摘要

Communication blackout is one of the most serious pitfalls of Wireless Sensor Networks (WSN) in industrial automation context. The industrial radio channel exhibits pronounced effects of multipath fading and wireless LAN (WLAN) interference that can potentially lead to temporary communication failures, as well as complete isolation of network devices. The current IWSN standards adopt known countermeasures to cope with the harshness of the radio channel, but they lack solutions specifically oriented to detect blackouts and self-recover the communication fulfilling hard deadline constraints. In this work we focus on the problem of blackout detection with specific interest for the WirelessHART standard, introducing a Blackout Detection Service (BDS) expressly addressed to multi-hop periodic communication with sensors and actuators. The BDS monitors end-to-end acknowledgement messages and builds specific metrics to promptly identify communication outages, enabling three criticality classes. The algorithm is tested in the ns-2 network simulator and results show that the proposed system is able to detect blackout events with reaction delays of the order of 4???5 times the refresh rate of nodes and to discriminate between small and temporary network issues and serious blackout scenarios, opening the field for recovery strategies.