Sensor node, base station, and sensor network system

• US 20070281758A1
• Filed: 03/21/2007
• Published: 12/06/2007
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shimura, Takanori, Ara, Koji, Yamashita, Shunzo, Ogata, Yuji
• Granted Patent: US 7,593,752 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01D 5/00 Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable G01D3/00 takes precedence; specially adapted for apparatus giving results other than momentary value of variable G01D1/00
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

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.

Claims

1. A sensor network system, comprising:

a sensor node comprising a first sensor, a first CPU for receiving data obtained from the first sensor, a first memory in which a software executed by the CPU is installed, a first wireless communication module for transmitting the data obtained from the first sensor, and a first interface controller; and

a base station comprising a second wireless communication module for receiving the data transmitted from the first wireless communication module of the sensor node, a second memory for storing the data to be transmitted to the sensor node, a second CPU for controlling the data stored in the second memory to be transmitted to the sensor node, a second sensor, and a second interface controller, wherein

the first sensor, the first CPU, the first memory, the first wireless communication module and the first interface controller are connected through a first bus, and

the second sensor, the second CPU, the second memory, the second wireless communication module and the second interface controller are connected through a second bus.

2. A sensor node for transmitting data to a base station, comprising:

a sensor;

a CPU for receiving the data obtained from the sensor; and

a real time clock that is installed outside of the CPU and connected to the CPU, wherein

when the data is not transmitted to the base station, the CPU transmits a start time to the real time clock, and the CPU becomes in a standby state.

3. The sensor node according to claim 2, wherein when the start time comes, the real time clock transmits a signal to the CPU.

4. The sensor node according to claim 2, wherein the start time is determined in accordance with a time when the sensor node transmits the data to the base station.

5. The sensor node according to claim 2, further comprising a memory for storing the data to be held by the CPU, wherein

the CPU, before transmitting the start time to the real time clock, stores the data to be held by the CPU in the memory.