Association Based Locationing for RFID

• US 20100148985A1
• Filed: 12/17/2008
• Published: 06/17/2010
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.), Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: MOLINA, VICTOR HUGO, LIN, LANG
• Granted Patent: US 8,456,306 B2
• Time in Patent Office: Days
• US Class Current: 340/825.490
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

An apparatus, system and techniques for determining a location of an RFID tag among a population of tags are disclosed. The system includes an RFID reader with at least one antenna port and a population of RFID tags. The population of tags can be homogenous or heterogeneous. The RFID reader varies its transmit power through one or more antenna ports resulting in a grouping of the RFID tags into clusters. In one embodiment, the reader utilizes multiple antennas to further define RFID tag clusters among the population. Each read tag is then uniquely associated with a defined cluster. Tag agents also can be provided among the population of tags facilitating definition of the clusters.

Claims

1. A method of mapping RFID tag locations to transmit power levels comprising:

setting a first signal of an RFID reader to a first signal strength or first radiation pattern;

providing the first signal to the population of tags;

associating a first tag responsive to the first signal with a first cluster of tags, the first cluster of tags being in an approximate first known physical location;

setting a second signal of the RFID reader to a second signal strength or second radiation pattern, the second signal strength different from the first signal strength and the second radiation pattern different from the first radiation pattern;

providing the second signal to the population of tags;

associating a second tag responsive to the second signal with the second cluster of tags, the second cluster of tags being in a different physical location than the first cluster of tags.

2. The method of claim 1, comprising establishing at least one of the first and second clusters using a tag agent, the tag agent being positioned among the population of tags at a pre-defined location.

3. The method of claim 2, comprising associating the first tag with a first tag agent associated with the first cluster of tags.

4. The method of claim 3, wherein the first cluster of tags comprises a plurality of tag agents.

5. The method of claim 2, comprising associating the second tag with a second tag agent associated with the second cluster of tags.

6. The method of claim 5, wherein the second cluster of tags comprises a plurality of tag agents.

7. The method of claim 2, wherein one tag among the population of tags is identified as the tag agent based on an amount of time the one tag is in a same location among the population of tags.

8. The method of claim 1, comprising associating the first tag to the second cluster.

9. The method of claim 1, comprising:

providing the first signal through a first antenna of the RFID reader; and

providing the second signal through a second antenna of the RFID reader.

10. The method of claim 1, comprising establishing N clusters of tags using N antennas of the RFID reader, N being an integer value greater than 1.

11. The method of claim 1, using at least one of a tag backscatter signal strength, phases and time of arrival to associate at least one of the first tag with the first cluster and the second tag with the second cluster.

12. A system for mapping RFID tag locations comprising:

a plurality of RFID tags; and

a REID reader comprising at least one antenna, the RFID reader configured to;

set a first signal of an RFID reader to a first signal strength or first radiation pattern;

provide the first signal through the at least one antenna to the population of tags;

associate a first tag responsive to the first signal with a first cluster of tags, the first cluster of tags being in an approximate first known physical location;

set a second signal of the RFID reader to a second signal strength or second radiation pattern, the second signal strength different from the first signal strength and the second radiation pattern different from the first radiation pattern;

provide the second signal through the at least one antenna to the population of tags;

associate a second tag responsive to the second signal with the second cluster of tags, the second cluster of tags being in a different physical location than the first cluster of tags.

13. The system of claim 12, wherein the REID reader comprises a plurality of antennas and one of the plurality of antennas transmits the first signal and another of the plurality of antennas transmits the second signal.

14. The system of claim 12, wherein the reader establishes at least one of the first and second clusters using a tag agent, the tag agent positioned among the population of tags at a pre-defined location and responsive to at least one of the first and second signal.

15. The system of claim 14, wherein the reader associates the first tag with a first tag agent associated with the first cluster of tags.

16. The system of claim 15, wherein the first cluster of tags comprises a plurality of tag agents.

17. The system of claim 14, wherein the reader associates the second tag with a second tag agent associated with the second cluster of tags.

18. The system of claim 17, wherein the second cluster of tags comprises a plurality of tag agents.

19. The system of claim 14, wherein the reader identifies one tag among the population of tags as the tag agent based on an amount of time the one tag is in a same location among the population of tags.

20. The system of claim 12, wherein the reader associates the first tag to the second cluster.

21. The system of claim 12, wherein the reader provides the first signal through a first antenna of the RFID reader and provides the second signal through a second antenna of the REID reader.

22. The system of claim 12, wherein the reader establishes N clusters of tags using N antennas associated with the RFID reader, N being an integer value greater than 1.

23. The system of claim 12, wherein the reader uses at least one of a tag backscatter signal strength, phase, and time of arrival to associate at least one of the first tag with the first cluster and the second tag with the second cluster.