Open Access

Distributed Time Synchronization in Wireless Sensor Networks with Coupled Discrete-Time Oscillators

EURASIP Journal on Wireless Communications and Networking20072007:057054

DOI: 10.1155/2007/57054

Received: 25 September 2006

Accepted: 30 March 2007

Published: 18 June 2007


In wireless sensor networks, distributed timing synchronization based on pulse-coupled oscillators at the physical layer is currently being investigated as an interesting alternative to packet synchronization. In this paper, the convergence properties of such a system are studied through algebraic graph theory, by modeling the nodes as discrete-time clocks. A general scenario where clocks may have different free-oscillation frequencies is considered, and both time-invariant and time-variant network topologies (or fading channels) are discussed. Furthermore, it is shown that the system of oscillators can be studied as a set of coupled discrete-time PLLs. Based on this observation, a generalized system design is discussed, and it is proved that known results in the context of conventional PLLs for carrier acquisition have a counterpart in distributed systems. Finally, practical details of the implementation of the distributed synchronization algorithm over a bandlimited noisy channel are covered.


Authors’ Affiliations

Center for Wireless Communications and Signal Processing Research, New Jersey Institute of Technology
Dipartimento di Elettronica e Informazione, Politecnico di Milano


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© O. Simeone and U. Spagnolini 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.