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Title
Algorithmic Aspects of the Time Synchronization Problem in Large-Scale Sensor Networks.

Authors
A. Hu, S. D. Servetto.

Status
To appear in ACM/Kluwer Journal on Mobile Networks and Applications (MONET), Special Issue on Wireless Sensor Networks, with selected (and revised) papers from ACM WSNA 2003. Invited Paper.

Abstract
We study the time synchronization problem for large-scale wireless sensor networks in the high-density regime. Our interest in this problem arises from a sensor networking application, where a large number of power-constrained radio transmitters coordinate their access to a Gaussian multiple access channel to cooperate in generating a waveform stronger than any individual node would be able to generate. In a companion paper to this one, we study theoretical aspects of a time synchronization mechanism that is optimal in the limit of asymptotically high network densities. In this work we summarize those results, and explore practical implementation issues of that mechanism in the context of networks with large, but finite, numbers of nodes. Through simulations, we find that the synchronization mechanism performs very well for finite (and relatively small) networks, maintaining tight clock synchronization indefinitely.

More:
Download paper: PDF file, gzipped PS file.
Download Matlab code for the simulator: tar file (start with README.txt).

Previous conference papers on the time synchronization problem:

A. Hu, S. D. Servetto. Asymptotically Optimal Time Synchronization in Dense Sensor Networks. In the Proceedings of the 2nd ACM International Workshop on Wireless Sensor Networks and Applications, San Diego, CA, September 2003 (held in conjunction with ACM MobiCom).

Conference papers dealing with a related distributed modulation problem:

A. Hu, S. D. Servetto. dFSK: Distributed Frequency Shift Keying Modulation in Dense Sensor Networks. In the Proceedings of the IEEE International Conference on Communications (ICC), Paris, France, June 2004.

A. Hu, S. D. Servetto. Optimal Detection for a Distributed Transmission Array. In the Proceedings of the IEEE International Symposium on Information Theory (ISIT), Yokohama, Japan, June-July 2003.