Computer Science Colloquium

From TimeSync to EmStar: What's really hard in sensor networks?

Jeremy Elson

Monday, April 26, 2004 11:30 A.M.
Room 1302 Warren Weaver Hall
251 Mercer Street
New York, NY 10012-1185

Colloquium Information:


Richard Cole, (212) 998-3119


Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low-power sensors and actuators. Sensor networks have enormous potential, but their design is challenging in many unexpected ways.

Our research started out in time synchronization -- an important service in any distributed system, but particularly crucial in sensor networks. We developed and implemented several new approaches that better support the unique requirements of this domain. For example, Reference-Broadcast Synchronization achieves high precision at low energy cost by leveraging the broadcast property inherent to wireless communication. A new multi-hop algorithm allows RBS timescales to be federated across broadcast domains.

When the time came to apply these new methods to academic and commercial systems that needed synchronization, we learned many interesting lessons. Perhaps most surprising: in sensor networks, applications that, on the surface, might seem to hinge on problems like time synchronization actually were hard for completely different reasons.

Based on this experience, we developed EmStar, a software framework for sensor networks. EmStar's goal is to make the hardest problem easier: writing software for an environment that is inherently unpredictable, dynamic, difficult to model, hard to observe, and always subject to Murphy's Law.


Dr. Jeremy Elson is a post-doctoral researcher at University of California, Los Angeles, in the Center for Embedded Networked Sensing. He received his Ph.D. (UCLA, 2003), M.S. (University of Southern California, 2000), and B.S. (Johns Hopkins University, 1996), all in Computer Science. Dr. Elson's dissertation work on time synchronization in low-power wireless sensor networks, advised by Prof. Deborah Estrin, earned the Edward K. Rice Outstanding Graduate Student award. His other research interests include operating system issues and programming models in distributed, self-organizing networks.

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