The synchronous flashing of fireflies is a spectacular example for self-organization in nature. Thousands of fireflies gather in trees and flash in unison using a distributed mechanism that can be understood by applying the theory of discrete coupled oscillators. This theory has successfully been used for modeling many synchronization and coordination phenomena, such as sleep cycles, firing of neurons, and vibration of bridges.
“We aim at advancing this field of science and transferring it to wireless networks,” Christian Bettstetter argues. Synchronization is an important building block in large networks of embedded systems, where synchrony should emerge in a distributed manner without having to rely on central entities.
Bettstetter and his team have developed a solution that works well in wireless networked systems. It exploits a combination of positive and negative coupling between devices and takes into account unreliable channels. “Together with Marc Timme from the Max Planck Institute for Dynamics and Self-Organization we have mathematically proven that the resulting algorithm always converges,” PhD student Johannes Klinglmayr concludes.
The algorithm has been implemented in the physical layer of a programmable radio for field tests. Bettstetter’s PhD student Günther Brandner is excited: “This is the first ever evaluation of convergence and precision of such algorithms on programmable radios.” It became obvious from these experiments that automatic phase rate adaptation is needed in a real-word setup. The achieved synchronization precision is then below one microsecond in a testbed with six radio boards.
Another goal is to investigate robustness aspects of self-organization against faulty devices. What happens if one or more devices misbehave in some manner? These studies are generalized to other forms of coordination in networks, such as consensus.
Convergence of self-organizing pulse coupled oscillator synchronization in dynamic networks
IEEE Transactions on Automatic Control, 2017
Guaranteeing global synchronization in networks with stochastic interactions
New Journal of Physics, 2012
Self-organizing synchronization with inhibitory-coupled oscillators …
ACM Transactions on Autonomous and Adaptive Systems, 2012
Emergent slot synchronization in wireless networks
IEEE Transactions on Mobile Computing, 2010