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Ultra-Low Duty Cycle MAC with Scheduled Channel Polling

Wei Ye, Fabio Silva, and John Heidemann
USC/Information Sciences Institute

Abstract

 Energy is a critical resource in sensor networks. MAC protocols such as S-MAC and T-MAC coordinate sleep schedules to reduce energy consumption. Recently, low-power listening (LPL) approaches such as WiseMAC and B-MAC exploit very brief polling of channel activity combined with long preambles before each transmission, saving energy particularly during low network utilization. Synchronization cost, either explicitly in scheduling, or implicitly in long preambles, limits all these protocols to duty cycles of 1-2%. We demonstrate that ultra-low duty cycles of 0.1% and below are possible with a new MAC protocol called scheduled channel polling (SCP). This work prompts three new contributions: First, we establish optimal configurations for both LPL and SCP under fixed conditions, developing a lower bound of energy consumption. Under these conditions, SCP can extend lifetime of a network by a factor of 3-6 times over LPL. Second, SCP is designed to adapt well to variable traffic. LPL is optimized for known, periodic traffic, and long preambles become very costly when traffic varies. In one experiment, SCP reduces energy consumption by a factor of 10 under bursty traffic. We also show how SCP adapts to heavy traffic and streams data in multi-hop networks, reducing latency by 85% and energy by 95% at 9 hops. Finally, we show that SCP can \emphoperate effectively on recent hardware such as 802.15.4 radios. In fact, power consumption of SCP decreases with faster radios, but that of LPL increases.

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

Ye06a
Wei Ye, Fabio Silva, and John Heidemann. Ultra-Low Duty Cycle MAC with Scheduled Channel Polling. In Proceedings of the Fourth ACM SenSys Conference , pp. 321-333. Boulder, Colorado, USA, ACM. November, 2006. <http://www.isi.edu/~johnh/PAPERS/Ye06a.html>. 
@inproceedings{Ye06a,
	author = "Wei Ye and Fabio Silva and John Heidemann",
	title = "Ultra-Low Duty Cycle MAC with Scheduled
            Channel Polling",
	booktitle = "Proceedings of the Fourth {ACM} {SenSys} Conference ",
	year = "2006",
	publisher = "{ACM}",
	address = "Boulder, Colorado, USA",
	month = "November",
	pages = "321--333",
	keywords = "s-mac, scp-mac, b-mac, lpl",
	url = "http://www.isi.edu/~johnh/PAPERS/Ye06a.html",
	pdfurl = "http://www.isi.edu/~johnh/PAPERS/Ye06a.pdf",
	myorganization = "USC/Information Sciences Institute",
	copyrightholder = "{ACM}",
}

Copyright

This paper is copyright © 2006 by ACM. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.

© 2006 $Date$