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Low-latency Synchronization of Loosely-coupled Sensornet Republishing

Unkyu Park and John Heidemann
USC/Information Sciences Institute

Abstract

Today many individual deployments of sensornets are successful, but they will have much greater impact when, rather than standing alone, they share data across deployments so each can build upon the others. We expect data to be shared over the Internet, and as the number of processing and reprocessing steps grows, \emphtimely data synchronization is increasingly important. Today, such sharing is often hard-coded or driven by fixed-interval polling. Fixed-interval polling can provide poor worst-case performance (mean latency approaching the data generation period), and best performance requires careful manual configuration of both poll period and phase. We instead propose Data Generation Tracking (DGT), a new family of adaptive polling algorithms that \emphlearn and predict good times to pull data to minimize both latency and unfruitful queries. Our approach avoids manual configuration and automatically adapts to outages and changes in data generation rate. To evaluate our work, we examine four sensornet deployments and develop a rough \emphmodel of sensornet data generation. We then use this model and replay of real traces to evaluate DGT, finding that, depending on application, its median latency is only 10-30% of that of fixed-interval polling, with a configurable rate of network load that is the same or slightly higher.

Availability

This paper is available in several formats: abstract web page with pointers and cites, PDF, paper copies can be obtained by mail to the authors. Copyright terms for this paper appear below.

Reference

Park09a: Unkyu Park and John Heidemann. Low-latency Synchronization of Loosely-coupled Sensornet Republishing. Technical Report ISI-TR-2009-660, USC/Information Sciences Institute, April, 2009. <http://www.isi.edu/~johnh/PAPERS/Park09a.html>.

@techreport{Park09a,
	author = "Unkyu Park and John Heidemann",
	title = "Low-latency Synchronization of Loosely-coupled Sensornet Republishing",
	institution = "USC/Information Sciences Institute",
	year = "2009",
	number = "ISI-TR-2009-660",
	month = "April",
	keywords = "sensornet, sensor-internet, republishing,
                  synchronization, RSS",
	url = "http://www.isi.edu/~johnh/PAPERS/Park09a.html",
	pdfurl = "http://www.isi.edu/~johnh/PAPERS/Park09a.pdf",
	myorganization = "USC/Information Sciences Institute",
	copyrightholder = "authors",
}

Copyright

This paper is copyright © 2009 by its authors. Permission to make digital or hard copies of part or all of this work for personal use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that new copies bear this notice and the full citation on the first page. Abstracting with credit is permitted.

To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission of the authors.