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MAC Stability in Sensor Networks at High Network Densities

Tyler McHenry and John Heidemann
USC/Information Sciences Institute

Abstract

 Although MAC protocols have been the subject of extensive study, there has been little study of MAC operation as network density (number of neighbors per node) increases. Although network densities are often low (2-12 neighbors), density can rise in special situations (such as hundreds of people attending a conference in the same room) and new deployments (such as dense instrumentation of a structure with a sensor network). In anticipation of these applications, this paper studies the stability of S-MAC as network density increases to densities of 50 to 150 neighbors, well beyond its current design parameters. We present a mathematical model of expected behavior, then use experiments to show the importance of accounting for clock offset. Although offset cannot easily be modeled, we show that a simulation closely matches the experimental data. Finally, we describe how an offset-aware MAC can correct for hardware variation to allow operations at twice the density of current S-MAC. Although the details are specific to S-MAC, the results apply more generally.

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

McHenry07a
Tyler McHenry and John Heidemann. MAC Stability in Sensor Networks at High Network Densities. Technical Report ISI-TR-2007-628, USC/Information Sciences Institute, January, 2007. <http://www.isi.edu/~johnh/PAPERS/McHenry07a.html>. 
@techreport{McHenry07a,
	author = "Tyler McHenry and John Heidemann",
	title = "{MAC} Stability in Sensor Networks at High Network Densities",
	institution = "USC/Information Sciences Institute",
	year = "2007",
	number = "ISI-TR-2007-628",
	month = "January",
	keywords = "dense network operation",
	url = "http://www.isi.edu/~johnh/PAPERS/McHenry07a.html",
	pdfurl = "http://www.isi.edu/~johnh/PAPERS/McHenry07a.pdf",
	myorganization = "USC/Information Sciences Institute",
	copyrightholder = "authors",
}

Copyright

This paper is copyright © 2007 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.


© 2007 $Date$