Wireless network node

• US 20090103464A1
• Filed: 05/11/2006
• Published: 04/23/2009
• Est. Priority Date: 05/11/2005
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Yamada, Shigeru, Ohba, Kohtaro
• Granted Patent: US 7,840,240 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 74/085 collision avoidance
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A communication procedure has been developed that allows even a low-rate CPU to perform stable communication so as to realized wireless network nodes, which have a long communication distance and also have a long battery life. Each wireless network node decides its own time slot number by use of random numbers and transmits it after delaying the transmission by the number of time slots. When receiving the unique number from the wireless network node, a master unit transmits, to the wireless network node, an ACK signal together with the unique number. When receiving its unique number, the wireless network node gets into a sleep state for a period of time. In this way, each time communication is established, the number of active wireless network nodes is reduced.

Claims

1. A wireless network node, comprising:

a transmitter;

a receiver; and

an interface for connection to the outside,

wherein, when a master unit calls a wireless network node, the wireless network node generates a random number in response to the received call signal so as to prevent collision against other wireless network nodes, converts the random number into a time slot value, and transmits its unique number to the master unit at that time slot by return,

when receiving the unique number, the master unit transmits, to the wireless network node, the unique number of the wireless network node by return,

when receiving the return unique number from the master unit, the wireless network node shuts off the power supply to a transmitting/receiving circuit for a predetermined time, and

the master unit transmits the power supply shutoff time of the transmitting/receiving circuit of the wireless network node according to the priority of the wireless network node when transmitting the unique number to the wireless network node by return.

2. The wireless network node according to claim 1,

wherein the master unit transmits an upper limit value of the random number, that is, a change in the number of time slots, when transmitting the unique number to the wireless network node by return.

3. The wireless network node according to claim 1,

wherein an additional low-power receiving circuit is provided in addition to a general receiving circuit, and when the additional low-power receiving circuit receives radio wave from the master unit at a different frequency, power is supplied to the general transmitting/receiving circuit.

4. The wireless network node according to claim 1,

wherein, when radio wave is transmitted from the master unit to the wireless network node so as to change the unique number of the wireless network node, the master unit first transmits the unique number of the wireless network node to the wireless network node,

at the timing when its unique number is received, the wireless network node transmits, to the master unit, that it is ready to change the unique number,

the master unit transmits the changed unique number to the wireless network node again, and

when receiving the changed unique number, the wireless network node performs a procedure for changing its unique number.

5. The wireless network node according to claim 1,

wherein, when the wireless network node is attached to an object or a person, a camera for capturing a still picture or a moving picture may be provided in the master unit, and

an image of the object or the person who carries the wireless network node is captured by the camera at the same time the unique number of the wireless network node from the master unit according to claim 5 is changed or the master unit reads the wireless network node.

6. The wireless network node according to claim 1,

wherein, when the master unit issues the unique number of the wireless network node, the unique number is generated from the number of the master unit, time, or the unique state of the wireless network node for the master unit or the slave unit.

7. The wireless network node according to claim 1,

wherein a sensor is attached to the master unit so as to detect the temperature or the state of an object or a person, and

when the sensor shows a reaction and the unique number of the wireless network node is received, or when the sensor shows the reaction while the unique number of the wireless network node is not received, the master unit performs a prescribed operation.

8. The wireless network node according to claim 1,

wherein a relay wireless network node is provided between the master unit and the wireless network node so as to prevent a radio wave coverage from being reduced due to noise around the master unit and to improve a communication distance.

9. The wireless network node according to claim 1,

wherein a sensor is attached to the slave unit so as to detect a slope or a movement, and when the sensor shows a reaction, the slave unit performs a prescribed operation.

10. The wireless network node according to claim 2,

wherein an additional low-power receiving circuit is provided in addition to a general receiving circuit, and when the additional low-power receiving circuit receives radio wave from the master unit at a different frequency, power is supplied to the general transmitting/receiving circuit.

11. The wireless network node according to claim 2,

wherein, when radio wave is transmitted from the master unit to the wireless network node so as to change the unique number of the wireless network node, the master unit first transmits the unique number of the wireless network node to the wireless network node,

at the timing when its unique number is received, the wireless network node transmits, to the master unit, that it is ready to change the unique number,

the master unit transmits the changed unique number to the wireless network node again, and

when receiving the changed unique number, the wireless network node performs a procedure for changing its unique number.

12. The wireless network node according to claim 2,

wherein, when the wireless network node is attached to an object or a person, a camera for capturing a still picture or a moving picture may be provided in the master unit, and

an image of the object or the person who carries the wireless network node is captured by the camera at the same time the unique number of the wireless network node from the master unit according to claim 5 is changed or the master unit reads the wireless network node.

13. The wireless network node according to claim 2,

wherein, when the master unit issues the unique number of the wireless network node, the unique number is generated from the number of the master unit, time, or the unique state of the wireless network node for the master unit or the slave unit.

14. The wireless network node according to claim 2,

wherein a sensor is attached to the master unit so as to detect the temperature or the state of an object or a person, and

when the sensor shows a reaction and the unique number of the wireless network node is received, or when the sensor shows the reaction while the unique number of the wireless network node is not received, the master unit performs a prescribed operation.

15. The wireless network node according to claim 2,

wherein a relay wireless network node is provided between the master unit and the wireless network node so as to prevent a radio wave coverage from being reduced due to noise around the master unit and to improve a communication distance.

16. The wireless network node according to claim 2,

wherein a sensor is attached to the slave unit so as to detect a slope or a movement, and when the sensor shows a reaction, the slave unit performs a prescribed operation.