Synchronized industrial wireless sensor network with IEEE 802.11 ad hoc data transmission

Abstract

In industrial applications of wireless sensor networks (WSNs) synchronized sampling of data on each sensor node is often required. Thus the wireless communication protocol needs to support accurate timing synchronization. If due to a high sampling rate also high data throughput is required, WSNs based on the IEEE 802.15.4 physical layer often do not provide sufficient data rate. Wireless communication based on the well established IEEE 802.11 (WLAN) standard provides high data throughput but not an accurate timing synchronization unless the protocol stack is severely changed. We propose a hybrid WSN which uses WLAN for high rate data transmission combined with a proprietary wireless communication system operating on Sub-GHz short range devices for synchronization. A consensus-based synchronization algorithm is used to be independent from the number of WSN nodes and node failure. The proposed hybrid WSN performs a two-step synchronization algorithm which can easily be executed on an 8-bit microcontroller and achieves a sampling jitter smaller than 50 μs.