Sensor node, base station, and sensor network system

• US 7,512,418 B2
• Filed: 08/23/2005
• Issued: 03/31/2009
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ara, Koji, Yamashita, Shunzo, Ogata, Yuji, Shimura, Takanori
• Primary Examiner(s): Pan; Yuwen
• Assistant Examiner(s): Jain; Ankur
• Application Number:
  US11/208,658
• Publication Number:
  US 20060172784A1
• Time in Patent Office: 1,316 Days
• Field of Search: 455/574
• US Class Current: 455/561
• 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 base station for transmitting a first signal to each of a plurality of sensor nodes, comprising:

a base station controller including a first memory for storing the first signal to be transmitted to each of the plurality of sensor nodes, a first CPU connected with the first memory, a first interface controller connected with the first memory and the first CPU, and a wired communication unit for wired communication; and

a base station wireless section carrying out communication with the plurality of sensor nodes, the base station wireless section including a second memory a second CPU connected with the second memory, a second interface controller connected with the second memory and the second CPU, and a wireless communication module connected to the second memory,

wherein the number of the first signals stored in the second memory is smaller than the number stored in the first memory,

wherein each of the sensor nodes comprises a third memory, a third CPU connected with the third memory, a third interface controller connected with the third memory and the third CPU, and a third wireless communication module connected with the third memory, and

wherein the second memory is identical to the third memory. the second CPU is identical to the third CPU, the second interface controller is identical to the third interface controller, and the third wireless communication module is identical to the wireless communication module.

2. The base station according to claim 1, wherein

the base station receives a second signal from each of the plurality of sensor nodes,

the first memory and the second memory further each stores a time when the second signal is received from each of the plurality of sensor nodes, and

a time stored in the first memory includes a time later than a time that is stored in the second memory.

3. The base station according to claim 1, further comprising:

a first CPU connected to the first memory;

a first interface controller connected to the first memory and the first CPU;

a second CPU connected to the second memory; and

a second interface controller connected to the second memory and the second CPU,

wherein the first memory and the second memory are connected through the first and second interface controllers to the serial interface.

4. The base station according to claim 2, wherein when the base station receives the second signal from one of the plurality of sensor nodes, if the first signal to be transmitted to said one of the sensor nodes is stored in the second memory, the first signal stored in the second memory is transmitted to said one of the sensor nodes.

5. The base station according to claim 2, wherein when the base station receives the second signal from any one of the plurality of sensor nodes, if the first signal to be transmitted to said one of the sensor nodes is not stored in the second memory, whether or not the first signal is stored in the first memory is judged.

6. The base station according to claim 2, wherein

each of the first signals, which are stored in the first memory and the second memory, is stored such that the plurality of sensor nodes are arrayed in an order of times when the second signals are received by the base station, and

the base station, after receiving the second signal from each of the plurality of sensor nodes, rewrites an order of the first signals which are stored in the first memory and the second memory.

7. The base station according to claim 2, wherein the base station periodically receives the second signal from each of the sensor nodes.

8. The base station according to claim 5, wherein if the first signal is stored in the first memory, the first signal stored in the first memory is transmitted to said one of the sensor nodes.

9. The base station according to claim 5, wherein if the first signal is not stored in the first memory, a third signal instead of the first signal is transmitted to said one of the sensor nodes.

10. The base station according to claim 9, wherein

the first signal includes a command signal for controlling each of the plurality of sensor nodes,

the second signal includes data obtained from a sensor included in each of the plurality of sensor nodes, and

the third signal is an empty signal indicating that there is no command signal for controlling each of the plurality of sensor nodes.