Power saving wireless telemetering system

• US 7,301,477 B2
• Filed: 10/19/2004
• Issued: 11/27/2007
• Est. Priority Date: 10/31/2003
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Isoyama, Kazuhiko, Kawasaki, Daisuke, Ohkuma, Takahiro
• Primary Examiner(s): Wong; Albert K.
• Application Number:
  US10/967,256
• Publication Number:
  US 20050122233A1
• Time in Patent Office: 1,134 Days
• Field of Search: 340/870.11, 340/870.06, 340/870.07, 340/539.19, 340/870.13
• US Class Current: 340/870.13
• CPC Class Codes: H04Q 2209/40 using a wireless architecture
• CPC Class Codes: H04Q 2209/883 where the sensing device enters an active or inactive mode
• CPC Class Codes: H04Q 2209/886 using energy harvesting, e.g. solar, wind or mechanical
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0248 dependent on the time of the day, e.g. according to expected transmission activity
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Disclosed is a telemetering system that comprises a wireless base station and a number of wireless sensor nodes. Each wireless sensor node includes a solar cell, a sensor for producing observation data indicating a quantity being measured, a wireless interface for receiving the observation data from the sensor when the node is activated, and a time-schedule memory for storing time-schedule data. Control circuitry briefly activates its own node by supplying power from the solar cell to the wireless interface at periodic intervals according to the time-schedule data of the memory and briefly establishes a wireless link to the base station. During the time the wireless link is briefly established, the control circuitry of each node transmits the observation data to the base station and updates its time-schedule memory if it receives time-schedule data from the base station.

Claims

1. A telemetering system comprising:

a wireless base station; and

a plurality of wireless sensor nodes, each wireless sensor node including;

a power source;

a sensor for producing observation data indicating a quantity being measured;

a wireless interface for receiving said observation data from the sensor when the wireless interface is activated;

a time-schedule memory for storing time-schedule data; and

control circuitry for briefly activating the wireless sensor node by supplying power to said wireless interface from said power source at periodic intervals according to the time-schedule data of said memory to establish a wireless link to the base station to receive time-schedule update data therefrom, and updating the time-schedule memory according to the received time-schedule update data and transmitting the observation data from the activated wireless interface to the base station.

2. The telemetering system of claim 1, wherein all the wireless sensor nodes are activated at times which do not overlap with each other.

3. The telemetering system of claim 1, wherein each of said wireless sensor nodes comprises a node memory for storing an upstream node identifier and at least one downstream node identifier, and wherein said control circuitry is configured to receive a packet from said base station when said wireless interface is briefly activated and forward the received packet to a downstream wireless sensor node if said received packet contains node identifiers corresponding to the node identifiers stored in said node memory.

4. The telemetering system of claim 1, wherein said control circuitry is configured to instruct said sensor to process measured quantity according to a measurement command to produce said observation data, and wherein said base station is configured to transmit the measurement command to each said wireless sensor node during the time the wireless sensor node is briefly activated.

5. The telemetering system of claim 1, wherein said time-schedule data comprises offset data indicating an offset time from a reference time and period data indicating a period between successive times at which the wireless interface is activated.

6. The telemetering system of claim 1, wherein said control circuitry comprises:

a packet processor connected to said wireless interface for establishing a wireless link with said base station when the packet processor is activated for setting the time-schedule data into said time-schedule memory;

a time-keeping device for producing data indicating a time of day; and

a power saving controller for briefly activating said packet processor and said wireless interface when the time of day of said time-keeping device coincides with each of a plurality of time instants indicated by the time-schedule data of said time-schedule memory.

7. The telemetering system of claim 6, wherein said packet processor is configured to:

receive a routing packet from said base station and store node identifiers into said node memory according to said routing packet;

receive a power saving packet from said base station and set time-schedule data contained in the received packet into said time-schedule memory; and

receive a command packet from said base station when the wireless interface is briefly activated and update the time-schedule memory if the command packet contains said time-schedule update data.

8. The telemetering system of claim 7, wherein said command packet further contains the measurement command, and wherein said packet processor is configured to instruct said sensor to process measured quantity according to the measurement command of the command packet.

9. The telemetering system of claim 1, wherein said plurality of wireless sensor nodes are geographically divided into a plurality of groups, and wherein said wireless base station is configured to respectively set the time-schedule data into the time-schedule memories of all of said wireless sensor nodes so that all the wireless sensor nodes of the same group are activated at times which do not overlap with each other.

10. The telemetering system of claim 1, wherein said plurality of wireless sensor nodes are geographically divided into a plurality of groups, and wherein said wireless base station is configured to respectively set the time-schedule data into the memory of all of said wireless sensor nodes so that the wireless sensor nodes of all of said groups are activated at times which do not overlap with each other.

11. The telemetering system of claim 1, wherein said power source comprises a solar cell.

36. The telemetering system according to claim 7, wherein the packet processor is configured to distinguish between a routing packet, a power saving packet, and a command packet based on a packet type field provided at a predetermined position within the received packet.

12. A method of operating a plurality of wireless sensor nodes from a wireless base station, wherein each of said wireless sensor nodes includes a sensor for producing observation data indicating a quantity being measured, a wireless interface for establishing an individual wireless link to said base station when the wireless sensor node is activated, and a time-schedule memory, the method comprising the steps of:

a) establishing a wireless link between said wireless base station and each of the sensor nodes and receiving, at each sensor node, time-schedule data from the base station, and setting the time-schedule data into the time-schedule memory of each sensor node;

b) briefly activating each sensor node by supplying power from a power source to the wireless interface at periodic intervals according to the time-schedule data of said time-schedule memory to establish a wireless link between each sensor node and said base station;

c) transmitting, from said base station, time-schedule update data to each briefly activated sensor node via said wireless link;

d) receiving, at each of the briefly activated sensor nodes, the time-schedule update data;

e) updating the time-schedule memory with the received time-schedule update data;

f) transmitting said observation data from each briefly activated sensor node to said base station; and

g) receiving the transmitted observation data at said base station.

13. The method of claim 12, wherein the step (a) comprises respectively setting the time-schedule data from said base station into the time-schedule memories of all of said sensor nodes so that all the sensor nodes are briefly activated at times which do not overlap with each other.

14. The method of claim 12, wherein each said wireless sensor node comprises a node memory for storing an upstream node identifier and at least one downstream node identifier, and further comprising the steps of receiving a packet from said base station at said briefly activated sensor node and forwarding the packet to a downstream wireless sensor node if said packet contains node identifiers corresponding to the node identifiers stored in said node memory.

15. The method of claim 12, further comprising the steps of:

transmitting, from said base station, a measurement command to the briefly activated sensor node;

receiving said measurement command at said briefly activated sensor node;

instructing the sensor to process measured quantity according to the measurement command to produce said observation data.

16. The method of claim 12, wherein said time-schedule data stored in said time-schedule memory comprises offset data indicating an offset time from a reference time and period data indicating a period between successive times at which the wireless sensor node is activated.

17. The method of claim 12, further comprising the steps of:

receiving a routing packet from said base station at said sensor node when the sensor node is constantly activated;

storing node identifiers contained in said routing packet into a node memory;

receiving a power saving packet containing said time-schedule data from said base station at said constantly activated sensor node;

storing the time-schedule data of the power saving packet into said time-schedule memory;

receiving, at the briefly activated sensor node, a command packet from said base station; and

updating the time-schedule memory if the received command packet contains said time-schedule update data.

18. The method of claim 17, wherein said command packet further contains the measurement command, and further comprising the step of instructing said sensor to process measured quantity according to the measurement command of the command packet to produce said observation data.

19. The method of claim 12, further comprising the steps of receiving an observation packet from a downstream node and forwarding the packet to an upstream node when said sensor node is briefly activated.

20. The method of claim 12, wherein said plurality of wireless sensor nodes are geographically divided into a plurality of groups, and wherein all wireless sensor nodes of the same group are briefly activated at times which do not overlap with each other.

21. The method of claim 12, wherein said plurality of wireless sensor nodes are geographically divided into a plurality of groups, and wherein the wireless sensor nodes of all of said groups are briefly activated at times which do not overlap with each other.

37. The method according to claim 17, wherein each of the wireless sensor nodes is configured to distinguish between a routing packet, a power saving packet, and a command packet based on a packet type field provided at a predetermined position within the received packet.

22. A method of operating a plurality of wireless sensor nodes from a wireless base station, wherein each of said wireless sensor nodes includes a sensor for producing observation data indicating a quantity being measured, a wireless interface for establishing an individual wireless link to said base station when the wireless sensor node is activated, and a time-schedule memory, the method comprising the steps of:

a) establishing a wireless link between said wireless base station and each of the sensor nodes and receiving, at each sensor node, time-schedule data from the base stations, and setting time-schedule data into the time-schedule memory of the sensor node;

b) briefly activating each of the sensor node by supplying power from a power source to the wireless interface at periodic intervals according to the time-schedule data of said time-schedule memory to establish a wireless link between each sensor note and said base station;

c) transmitting a command packet containing time-schedule update data from said base station to each of the briefly activated sensor nodes;

d) receiving said command packet at each of the briefly activated sensor nodes;

e) updating the time-schedule memory of each said sensor node according to the time-schedule update data contained in the received command packet;

f) transmitting said observation data from each of the briefly activated sensor nodes to said base station; and

g) receiving, at said base station, the observation data transmitted from each of the briefly activated sensor nodes.

23. The method of claim 22, wherein said command packet contains a measurement command and the step (f) comprises the steps of:

reading said measurement command from the received command packet; and

processing the quantity being measured according to the measurement command to produce said observation data.

24. The method of claim 22, further comprising the steps of receiving an observation packet from a downstream node and forwarding the packet to an upstream node when said sensor node is briefly activated.

25. The method of claim 22, wherein each said wireless sensor node comprises a node memory for storing an upstream node identifier and at least one downstream node identifier, and wherein, in each of said wireless sensor nodes, the step (d) further comprises the steps of:

determining whether said command packet is destined for a downstream wireless sensor node;

if said command packet is destined for the downstream wireless sensor node, determining whether said command packet contains node identifiers corresponding to the node identifiers stored in said node memory; and

if said command packet contains said corresponding node identifiers, forwarding the command packet to the downstream wireless sensor node.

26. The method of claim 25, further comprising the steps of:

determining whether said command packet contains time-schedule update data of the downstream wireless sensor node; and

if said command packet contains said time-schedule update data of the downstream wireless sensor node, updating the time-schedule memory of the local wireless sensor node with the time-schedule update data of the downstream wireless sensor node.

27. The method of claim 22, wherein said time-schedule data of step (a) comprises a timing offset value and a period value, and wherein the step (b) comprises, in each of said wireless sensor nodes, the steps of:

b₁) determining a start timing by adding said timing offset value to a predetermined reference timing;

b₂) comparing a current time of day to the start timing for detecting a match;

b₃) if a match detected at step (b₂), activating said wireless interface for a predetermined interval;

b₄) determining a start timing for a next activation of said wireless interface by adding said period value to the previous start timing;

b₅) repeating steps (b₂) to (b₄) until said wireless interface is activated a predetermined number of times; and

b₆) repeating steps (b₁) to (b₅) when said wireless interface is activated said predetermined number of times.

28. A wireless sensor node for a telemetering system including a wireless base station which transmits power saving time-schedule data to a plurality of wireless sensor nodes, wherein said wireless sensor node is one of said plurality of wireless sensor nodes, said wireless sensor node comprising:

a power source;

a sensor for producing observation data indicating a quantity being measured;

a wireless interface for receiving said observation data from the sensor when the wireless interface is activated;

a time-schedule memory for storing time-schedule data; and

control circuitry for briefly activating the wireless sensor node by supplying power from said power source to said wireless interface at periodic intervals according to the time-schedule data of said memory to establish a wireless link to the base station to receive time-schedule update data therefrom, and updating the time-schedule memory according to the received time-schedule update data and transmitting the observation data from the activated wireless interface to the base station through said established wireless link.

29. The wireless sensor node of claim 28, wherein said control circuitry comprises a node memory for storing an upstream node identifier and at least one downstream node identifier, and wherein said control circuitry is configured to receive a packet from said base station when said wireless sensor node is briefly activated and forward the received packet to a downstream wireless sensor node if said received packet contains node identifiers corresponding to the node identifiers stored in said node memory.

30. The wireless sensor node of claim 28, wherein said control circuitry is configured to receive a measurement command from said base station when said wireless sensor node is briefly activated and instruct said sensor to process measured quantity according to the received measurement command to produce said observation data.

31. The wireless sensor node of claim 28, wherein said time-schedule data stored in said time-schedule memory comprises offset data indicating an offset time from a reference time and period data indicating a period between successive times at which the wireless sensor node is activated.

32. The wireless sensor node of claim 28, wherein said control circuitry comprises:

a packet processor connected to said wireless interface for establishing a wireless link with said base station when the packet processor is activated for setting the time-schedule data into said time-schedule memory;

a time-keeping device for producing data indicating a time of day; and

a power saving controller for briefly activating said packet processor and said wireless interface when the time of day of said time-keeping device coincides with each of a plurality of time instants indicated either by the time-schedule data and the time-schedule update data of said time-schedule memory.

33. The wireless sensor node of claim 32, wherein said packet processor is configured to:

receive a routing packet from said base station and store node identifiers into said node memory according to said routing packet;

receive a power saving packet from said base station and set the time-schedule data into said time-schedule memory according to said power saving packet; and

receive a command packet containing said time-schedule update data from said base station when the wireless interface is briefly activated and update the time-schedule memory according to said time-schedule update data of the command packet.

34. The wireless sensor node of claim 33, wherein said command packet further contains the measurement command, and wherein said packet processor is configured to instruct said sensor to process measured quantity according to the measurement command of the command packet.

35. The wireless sensor node of claim 28, wherein said power source comprises a solar cell.

38. The wireless sensor node according to claim 33, wherein the packet processor is configured to distinguish between a routing packet, a power saving packet, and a command packet based on a packet type field provided at a predetermined position within the received packet.