Low-Complex Synchronization Algorithms for Embedded Wireless Sensor Networks

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 communications based on the well-established IEEE 802.11 wireless local area network (WLAN) standard provides high data throughput but not an accurate timing synchronization unless the protocol stack is severely changed. We propose two low-complexity consensus-based synchronization algorithms for the hybrid WSN introduced, which are executable at limited embedded computing capacity, e.g., on an 8 bit microcontroller. A time division multiple access-based synchronization packet broadcasting with three-step-controlled or proportional-integral (PI)-controlled clock adjustment enables 1 kHz sensor sampling rate with a sampling jitter <15 μs for the three-step-controlled synchronization algorithm and <1 μs for the PI-controlled algorithm.