Methods and apparatus of meshing and hierarchy establishment for tracking devices

• US 20050247775A1
• Filed: 12/29/2004
• Published: 11/10/2005
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: G2 Microsystems Pty Limited
• Original Assignee: G2 Microsystems Pty Limited
• Inventors: Smith, Geoffrey J., Ryan, Philip, Gloekler, John S., O'Sullivan, John
• Granted Patent: US 7,212,122 B2
• Time in Patent Office: Days
• US Class Current: 235/375
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G08B 21/0227 System arrangements with a plurality of child units
• CPC Class Codes: G08B 21/0261 System arrangements wherein the object is to detect trespassing over a fixed physical boundary, e.g. the end of a garden
• CPC Class Codes: G08B 21/0269 System arrangements wherein the object is to detect the exact location of child or item using a navigation satellite system, e.g. GPS
• CPC Class Codes: G08B 21/0275 Electronic Article Surveillance [EAS] tag technology used for parent or child unit, e.g. same transmission technology, magnetic tag, RF tag, RFID

Abstract

Devices, such as tracking devices, cooperate with one another to establish the routing necessary for a relay network in which a device having power-efficient and data-reliable communication with an access portal, operates to relay messages from devices which do not have an acceptable communication path to and/or from the access portal. In one aspect of the present invention, a plurality of devices synchronously determine whether an acceptable communication path can be established between themselves an one or more access portals by measuring the signal strength of an access portal beacon. In another aspect of the present invention, one or more devices, which have determined that an acceptable communication path can be established between themselves and an access portal, transmit information regarding their availability to relay messages on behalf of devices which have determined than an acceptable communication path cannot be established between themselves and an access portal.

Claims

1. A method of communicating information among a plurality of tags, comprising:

a) determining, within a first one of the plurality of tags, whether a pre-determined time for powering up and engaging in a route set-up operation has arrived;

b) powering up and listening for an access portal beacon if the determination of (a) is affirmative;

c) determining whether the access portal beacon has been detected;

d) identifying, if the determination of (c) is affirmative, the tag as a level 1 tag, and recording the level number;

e) determining whether a pre-determined time for broadcasting a level 1 announcement has arrived;

f) broadcasting, if the determination of (e) is affirmative, a level 1 announcement;

g) determining, if the determination of (c) is negative, whether a first time period has expired; and

h) listening, if the determination of (g) is affirmative for the broadcast of a level 1 announcement.

2. The method of claim 1, further comprising:

i) determining whether the broadcast of a level 1 announcement has been received;

j) identifying, if the determination of (i) is affirmative, the tag as a level 2 tag, and recording the level number.

3. The method of claim 2, further comprising:

k) determining, subsequent to (j), whether a pre-determined time for broadcasting a level 2 announcement has arrived; and

l) broadcasting, if the determination of (k) is affirmative, a level 2 announcement.

4. The method of claim 1, wherein determining whether the access portal beacon has been detected comprises:

receiving a signal;

determining whether the strength of the received signal is above a pre-determined threshold; and

determining that the received signal represents an access portal beacon.

5. The method of claim 4, further comprising:

determining a charge level of a battery that supplies power to the first tag; and

determining the transmit power level required to transmit data to the access portal within a set of constraints.

6. The method of claim 5, wherein the constraints comprise data rate and bit error rate.

7. The method of claim 1, further comprising, subsequent to broadcasting a level 1 announcement, entering a low power state.

8. The method of claim 3, further comprising, subsequent to broadcasting a level 2 announcement, entering a low power state.

9. The method of claim 3, wherein the first tag comprises an RFID communication module, a processor module coupled to the RFID communication module, and a wireless communication module coupled to the processor module.

10. A method of communicating information among a plurality of tags, comprising:

a) determining, within a first one of the plurality of tags, whether a pre-determined time for transmitting data has arrived;

b) determining, if the determination of (a) is affirmative, whether the tag has data to transmit;

c) determining, if the determination of (b) is affirmative, whether the access portal is within one hop of the tag;

d) sending, if the determination of (c) is affirmative, the data to the access portal; and

e) sending, if the determination of (c) is negative, the data to a second one of the plurality of tags;

wherein the second one of the plurality of tags has fewer hops between itself and the access portal than does the first one of the plurality of tags.

11. The method of claim 10, wherein the second one of the plurality of tags has one hop fewer between itself and the access portal than does the first one of the plurality of tags.

12. The method of claim 11, the first tag and the second tag each comprise an RFID communication module, a processor module coupled to the RFID communication module, and a wireless communication module coupled to the processor module.

13. The method of claim 11, further comprising:

entering, subsequent to sending the data to the access portal, a low power state.

14. The method of claim 11, further comprising:

entering, subsequent to sending the data to the second tag, a low power state.

15. The method of claim 13, further comprising:

determining, prior to determining whether the tag has data to transmit, whether an amount of battery charge available to the tag is above a pre-determined threshold; and

entering, if the battery charge is below the pre-determined threshold, a low power state.