Synchronization

The synchronous flashing of fireflies and other synchronization phenomena are spectacular examples for emergent and adaptive behavior in natural systems. For instance, thousands of fireflies gather in trees and flash in unison using a distributed mechanism that can be understood using the theory of coupled oscillators. This theory has successfully been used for modeling many other 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 technological applications, in particular to wireless communication networks. “Synchronization is an important building block in large networks of embedded systems,” Christian Bettstetter argues. Synchrony should emerge in a distributed manner without having to rely on central entities. The team has developed a solution that works well in wireless systems and implemented it on a programmable hardware platform for field tests. Johannes Klinglmayr is very excited about the results. “Let’s see whether measurements in a real-world environment will confirm our promising simulation results” the researcher and PhD candidate says. We also investigate robustness aspects of self-organizing synchronization against faulty nodes. What happens if one or more devices misbehave in some manner? The idea is to use an approach from neuroscience and combine it with own results. “We have mathematically proven that the resulting algorithm converges,” Klinglmayr concludes.

Research Topics

• Algorithm design and concepts
• Convergence proofs and robustness aspects
• Synchronization in wireless communication systems

Selected Publications

J. Klinglmayr, C. Kirst, C. Bettstetter, M. Timme. Guaranteeing global synchronization in networks with stochastic interactions. New Journal of Physics, vol. 14, no. 073031, July 2012.

J. Klinglmayr, C. Bettstetter. Self-organizing synchronization with inhibitory-coupled oscillators: convergence and robustness. ACM Transactions on Autonomous and Adaptive Systems, vol. 7, no. 3, article 30, September 2012.

A. Tyrrell, G. Auer, C. Bettstetter. Emergent slot synchronization in wireless networks. IEEE Transactions on Mobile Computing, vol. 9, no. 5, pp. 719-732, May 2010.

Demonstrations

Electronic Fireflies. Electronic devices mimic the behavior of fireflies. The elements blink with a certain frequency and are attached with a light sensor to notice blinking from others. The devices gradually adjust to each other until they blink in synchrony.

BuzzFlies. The iPhone app Buzzflies lets iPhones mimic an “audio-firefly” and beep with a certain frequency. Via these audio signals, phones synchronize.

Wireless Pendula. So far the interactions between the entities were noticeable, light signals or audio signal. For the synchronization demonstration via pendula, we let the entities interact via radio signals. Therefore we apply small wireless devices that are able to send and receive short radio signals that take over the pulsation. The demonstrator was realized within an internship by a student, see movie.

Sensor Network