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 coupled oscillators. This theory has successfully been used for modeling synchronization and coordination phenomena in different areas, including neuroscience, physics, and construction engineering.
“We aim at advancing this field of science and transferring it to wireless communication networks,” Christian Bettstetter says. Time 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.
The team has developed and patented a firefly-inspired algorithm and implemented it on programmable radios for field tests. It became obvious from these experiments that an automatic phase rate correction is needed in real-word setups. In a testbed setup such a mechanism led to synchronization precisions below one microsecond.
Theoretical research on self-organizing synchronization was made in collaboration with researchers from the Max Planck Institute for Dynamics and Self-Organization and the Rockefeller University. A mathematical proof was produced showing that, given certain assumptions, the synchronization algorithm always converges. In addition, an interesting insight was gained: unreliable channels or intentionally incomplete communication between entities can actually have beneficial effects on synchronization guarantees and precision. Such stochastic coupling can be exploited to improve the synchronization behavior, which is subject of ongoing research.
J. Klinglmayr, C. Bettstetter, M. Timme, and C. Kirst. Convergence of self-organizing pulse coupled oscillator synchronization in dynamic networks. IEEE Transactions on Automatic Control, 2017.
G. Brandner, U. Schilcher, and C. Bettstetter. Firefly synchronization with phase rate equalization and its experimental analysis in wireless systems. Computer Networks, 2016.
J. Klinglmayr and C. Bettstetter. Self-organizing synchronization with inhibitory-coupled oscillators: Convergence and robustness. ACM Transactions on Autonomous and Adaptive Systems, 2012.
J. Klinglmayr, C. Kirst, C. Bettstetter, and M. Timme. Guaranteeing global synchronization in networks with stochastic interactions. New Journal of Physics, 2012.
A. Tyrrell, G. Auer, and C. Bettstetter. Emergent slot synchronization in wireless networks. IEEE Transactions on Mobile Computing, 2010.
R. Leidenfrost and W. Elmenreich. Firefly clock synchronization in an 802.15.4 wireless network. EURASIP Journal on Embedded Systems, 2009.