Cross-Layer Design for Low-Power Wireless Sensor Node Using Wave Clock

Takashi TAKEUCHI  Yu OTAKE  Masumi ICHIEN  Akihiro GION  Hiroshi KAWAGUCHI  Chikara OHTA  Masahiko YOSHIMOTO  

IEICE TRANSACTIONS on Communications   Vol.E91-B   No.11   pp.3480-3488
Publication Date: 2008/11/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e91-b.11.3480
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Emerging Technologies for Practical Ubiquitous and Sensor Networks)
cross-layer design,  crystal oscillator,  long-wave standard time code,  low power listening,  MAC,  

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We propose Isochronous-MAC (I-MAC) using the Long-Wave Standard Time Code (so called "wave clock"), and introduce cross-layer design for a low-power wireless sensor node with I-MAC. I-MAC has a periodic wakeup time synchronized with the actual time, and thus we take the wave clock. However, a frequency of a crystal oscillator varies along with temperature, which incurs a time difference among nodes. We present a time correction algorithm to address this problem, and shorten the time difference. Thereby, the preamble length in I-MAC can be minimized, which saves communication power. For further power reduction, a low-power crystal oscillator is also proposed, as a physical-layer design. We implemented I-MAC on an off-the-shelf sensor node to estimate the power saving, and verified that the proposed cross-layer design reduces 81% of the total power, compared to Low Power Listening.