Wireless Sensor Networks (WSNs) consist of multiple sensor nodes which are limited in energy supply and computational power, but have to provide robust data transmission from a data source to a data sink. The complexity of the networks can reache from simple point-to-point connections to widely distributed mesh-networks of hundreds of nodes.
In the first topic covered in this book we investigate real-time WSNs in simple star topology for closed loop control applications with sampling rates up to 100 Hz. The most challenging criterion is the reliability of the data transmission to keep the control loop stable. A proposal to improve the reliability in combination with reduced energy consumption is presented and evaluated.
In the second topic we propose a novel synchronization method between multiple sensor nodes operating in any topology or spatial arrangement, with low computational complexity. The distributed synchronization algorithm is performed on two levels: coarse and fine synchronization. With the used low-power and low-performance hardware we reached synchronization deviations below 1 μs.