Method for reporting and accumulating data in a wireless communication network

• US 8,023,441 B2
• Filed: 12/20/2005
• Issued: 09/20/2011
• Est. Priority Date: 12/20/2004
• Status: Expired due to Fees

• Current Assignee: Honeywell International SARL (Honeywell International Inc.), Yokogawa USA, Inc. (Yokogawa Electric Corporation)
• Original Assignee: Sensicast Systems
• Inventors: Werb, Jay Philip, Berry, Victor A.
• Primary Examiner(s): Sheikh; Ayaz R
• Assistant Examiner(s): HALIYUR, VENKATESH N
• Application Number:
  US11/312,269
• Publication Number:
  US 20060187866A1
• Time in Patent Office: 2,100 Days
• Field of Search: 370228-463, 455/343.1, 455550-574
• US Class Current: 370/311
• CPC Class Codes: G01D 2204/45 Utility meters networked together within a single building
• CPC Class Codes: G01D 4/004 Remote reading of utility meters to a fixed location
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 40/32 for defining a routing cluster membership
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A method and apparatus for coordinating communication in a wireless sensor network may include a plurality of nodes, such as routers, edge nodes, data accumulators and/or gateways. Time management functions, such as determining an elapsed time, may be controlled based on a detected temperature, e.g., a temperature detected at a node, and/or based on a detected clock skew between two or more clocks in two or more different devices. Accurate time management may allow for devices to more accurately coordinate communication instances, e.g., communication that occurs at periodic wake up times. A cluster head, such as a data accumulator, may be associated with a network after its initial formation and cause nodes in the network to alter their hierarchy in the network, thereby making the cluster head accumulator a parent to nodes in the network. Nodes having a relatively lower hop count may have a higher battery capacity than nodes having a higher hop count.

Claims

1. A method for coordinating communication in a wireless sensor network, comprising:

associating a first node with a wireless sensor network including at least two nodes associated with each other in a parent/child relationship, the first node being associated with the wireless sensor network such that the first node functions as a parent or child to at least one other node; and

determining a wake up time for the first node to wake up and listen for or broadcast a signal regarding communication with a parent or child node, the wake up time being determined based on a detected temperature at the first node, wherein determining further comprises;

determining a wake up time period;

determining an elapsed time;

comparing the elapsed time to the wake up time period;

controlling the first node to wake up when the elapsed time equals the wake up time period; and

wherein the elapsed time is adjusted based on the detected temperature.

2. The method of claim 1, wherein the elapsed time is determined based on a temperature dependent frequency change formula of the form K1*(T−

K2), where K1 and K2 are constants and T is the detected temperature.

3. The method of claim 1, wherein the wake up time is determined according to a schedule.

4. The method of claim 1, wherein the first node functions as a parent to a second node, and the first node is controlled to wake up and send a beacon based on a pseudorandom schedule.

5. The method of claim 4, wherein the second node wakes up to communicate with the first node according to the pseudorandom schedule.

6. The method of claim 5;

wherein the second node determines a wake up time for the second node that is determined based on a detected temperature at the second node.

7. The method of claim 1, wherein the first node has an internal timer that is used to determine an elapsed time.

8. The method of claim 7, wherein elapsed time determined by the internal timer is adjusted based on the detected temperature.

9. The method of claim 1, wherein the step of determining comprises determining an elapsed time that is adjusted based on the detected temperature using a lookup table.

10. The method of claim 9, wherein values in the lookup table are generated based on empirical measurement of a plurality of different timers.

11. The method of claim 9, wherein a lookup table used to determine the elapsed time is selected based on an age of the node.

12. The method of claim 9, wherein a lookup table used to determine the elapsed time is selected based on whether the detected temperature is increasing, decreasing or constant.

13. The method of claim 1, wherein the wake up time is determined based on a clock skew determined between a clock in the first node and a clock in a parent or child node.

14. The method of claim 1, wherein the first node is a router and the second node is an edge node.

15. The method of claim 1, wherein the first and second nodes are routers.

16. A method for coordinating communication in a wireless sensor network, comprising:

associating a first node with a wireless sensor network including at least two nodes associated with each other in a parent/child relationship, the first node being associated with the wireless sensor network such that the first node functions as a parent or child to at least one other node;

determining a wake up time for the first node to wake up and listen for a signal regarding communication with a second node that has a parent or child relationship with the first node, the wake up time being determined based on a determined clock skew between a clock in the first node and a clock in the second node, and wherein determining comprises;

determining a wake up time period to a next wake up time and adjusting the wake up time period based on the determined clock skew;

controlling the first node to wake up and listen for the signal based on the wake up time, the first node listening for the signal for a first time period;

controlling the first node to wake up and listen for the signal at a subsequent wake up time for a second time period that is longer than the first time period if the first node does not detect the signal during the first time period; and

wherein the first node is controlled to not listen for the signal at the subsequent wake up time if the second time period exceeds a threshold;

wherein the second time period is determined based on a lookup table;

and wherein the first node is controlled to not listen for the signal at the subsequent wake up time if values in the lookup table are exhausted.

17. The method of claim 16, wherein the clock skew is determined based on at least one comparison of a predicted signal transmission time with an actual signal transmission time for the second node.

18. The method of claim 16, wherein the first node is a child of the second node.

19. The method of claim 16, wherein the signal is a beacon and the second node emits a beacon on a defined schedule.

20. The method of claim 16, wherein the step of determining comprises:

determining an elapsed time;

comparing the elapsed time to a wake up time period; and

controlling the first node to wake up at the wake up time when the elapsed time equals the wake up time period.

21. The method of claim 16, wherein the wake up time is determined based on a detected temperature at the first node.

22. The method of claim 16, wherein the first node is an edge node, and the second node is a router.