Synchronization algorithms based on the theory of pulse-coupled oscillators are evaluated on programmable radios. It is experimentally demonstrated that the stochastic nature of coupling is a key ingredient for convergence to synchrony. We propose a distributed algorithm for automatic phase rate equalization and show that synchronization precisions below one microsecond are possible.
The mathematical modeling of pulse-coupled biological oscillators offers a fully decentralized and scalable approach for time synchronization. There is a broad spectrum of work on pulse-coupled oscillators in physics, biology, neuroscience, and other disciplines. The communications engineering community has been interested to transfer these results to the synchronization of nodes in wireless networks. A one-to-one transfer is infeasible due to the differences between wireless and biological communications. Several extensions and modifications are required with respect to delays, noise, multihop communications, and sync words.
Cooperative relaying has been developed for wireless communications to mitigate the negative effects of small-scale fading caused by multipath propagation. A huge amount of research has been done in the past ten years to assess benefits and drawbacks of such techniques by simulations and analytical means. It is surprising, however, that only few studies with real-world measurements in realistic environments were published so far. The goal of a research team led by Christian Bettstetter at Klagenfurt’s NES institute is to contribute toward closing this research gap. Based on an implementation of a simple cooperative relaying protocol on the programmable radio platform WARP, measurements were conducted to evaluate the packet delivery performance in a car-to-car communications scenario. The results will be published in IEEE Wireless Communications Letters. “We studied the ratio and temporal correlation of packet delivery for suburban and highway environments using three cars serving as sender, relay, and destination,” Günther Brandner, a researcher in the project team, explains.