Sensor node, base station, and sensor network system

mi iiiiiii ill mi mi Iiii iiijiip mi mil mi mi mi

(12) United States Patent

Ara et al.

(io) Patent No.: (45) Date of Patent:

US 7,512,418 B2 Mar. 31, 2009

(54) SENSOR NODE, BASE STATION, AND SENSOR NETWORK SYSTEM

(75) Inventors: Koji Ara, Kodaira (JP); Yuji Ogata, Hachioji (JP); Shunzo Yamashita, Musasino (JP); Takanori Shimura,

Chiba (JP)

(73) Assignee: Hitachi, Ltd., Tokyo (JP)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 324 days.

(21) Appl.No.: 11/208,658

(22) Filed: Aug. 23, 2005

(65) Prior Publication Data

US 2006/0172784 Al Aug. 3, 2006

(30) Foreign Application Priority Data

Jan. 31,2005 (JP) 2005-022375

(51) Int. CI.

H04M1/00 (2006.01)

(52) U.S. CI 455/561; 455/574

(58) Field of Classification Search 455/574

See application file for complete search history.

(56) References Cited

U.S. PATENT DOCUMENTS 5,323,418 A * 6/1994 Ayerstetal 375/148

6,647,266 B2 * 11/2003 Kang et al 455/453

2001/0055980 Al* 12/2001 Sato 455/552

2005/0200002 Al * 9/2005 Yamashita 257/723

2006/0176169 Al * 8/2006 Doolin et al 340/521

FOREIGN PATENT DOCUMENTS

JP 11-65915 8/1997

OTHER PUBLICATIONS

Rhee, Sokwoo, "Artifact-Resistant Power-Efficient Design of Finger-Ring Plethysmographic Sensors", IEEE Transactions on Biomedical Engineering, Vo. 48, No. 7, Jul. 2001, pp. 795-805. "Mote Hardware Session", Crossbow, Smarter Sensors in Silicon, pp. 1-40.

* cited by examiner

Primary Examiner—Yuwen Pan
Assistant Examiner—Ankur Jain

(7'4) Attorney, Agent, or Firm—Reed Smith LLP; Juan Carlos A. Marquez, Esq.

(57) ABSTRACT

This invention achieves lower electric power consumption of a sensor node for carrying out an intermittent operation, in a sensor net system. A time when the sensor node transmits a signal to a base station is estimated. Then, in accordance with the estimation, a table for storing a signal transmitted from the sensor node is installed in a wireless section of the base station. Consequently, a communication time between the sensor node and the base station can be made shorter. Also, a start time of a micro computer is set for RTC inside the sensor node, so the micro computer inside the sensor node can be put in the standby state.

10 Claims, 18 Drawing Sheets