Localization Using Virtual Antenna Arrays In Modulated Backscatter RFID Systems

• US 20100309017A1
• Filed: 03/08/2010
• Published: 12/09/2010
• Est. Priority Date: 03/11/2009
• Status: Active Grant

• Current Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Original Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Inventors: Tkachenco, Artem, Ramchandran, Kannan, Wild, Ben J., Madhow, Upamanyu
• Granted Patent: US 8,446,253 B2
• Time in Patent Office: Days
• US Class Current: 340/825.49
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14

Abstract

A localization method for use in a tag communication system includes associating a supertag having a plurality of tags with an item, reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals, estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters, and localizing the item in accordance with the plurality of derived signal parameters. The backscatter signals are read by a tag reader having a single antenna and the item is localized in accordance with an antenna array technique performed upon the plurality of derived signal parameters. The backscatter signals are read with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags, and the item is localized in accordance with the further pluralities of derived signal parameters.

Claims

1. A localization method for use in a tag communication system, comprising:

associating a supertag having a plurality of tags with an item;

reading backscatter signals from the tags of the plurality of tags to provide a plurality of backscatter signals;

estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters; and

localizing the item in accordance with the plurality of derived signal parameters.

2. The localization method for use in a tag communication system of claim 1, wherein the backscatter signals are read by a tag reader having a single antenna further comprising localizing the item in accordance with an antenna array technique performed upon the plurality of derived signal parameters.

3. The localization method for use in a tag communication system of claim 1, further comprising:

reading the backscatter signals with an antenna array to provide a further plurality of derived signal parameters for each tag of the plurality of tags; and

localizing the item in accordance with the further pluralities of derived signal parameters.

4. The localization method for use in a tag communication system of claim 3, further comprising calibrating the plurality of derived signal parameters in accordance with the further pluralities of derived signal parameters.

5. The localization method for use in a tag communication system of claim 1, further comprising:

performing the step of reading backscatter signals from the tags of the plurality of tags at a plurality of different positions to provide a further plurality of derived signal parameters for each tag of the plurality of tags; and

localizing the item in accordance with the further pluralities of signals.

6. The localization method for use in a tag communication system of claim 1, wherein the signal parameter comprises phase information.

7. The localization method for use in a tag communication system of claim 1, wherein the signal parameter comprises time information.

8. The localization method for use in a tag communication system of claim 1, wherein the tags of the plurality of tags are disposed on the supertag with a known geometric relationship with each other.

9. The localization method for use in a tag communication system of claim 8, wherein the tags of the plurality of tags are disposed on the supertag in a linear array.

10. The localization method for use in a tag communication system of claim 8, wherein the tags of the plurality of tags are disposed on the supertag in a two dimensional array.

11. The localization method for use in a tag communication system of claim 8, wherein the tags of the plurality of tags are disposed on the supertag in a three dimensional array.

12. The localization method for use in a tag communication system of claim 1, further comprising determining a tag reader location in accordance with the plurality of derived signal parameters.

13. The localization method for use in a tag communication system of claim 1, further comprising:

assigning identity information to at least one tag of the plurality of tags;

determining the identity information of the at least one tag in accordance with a backscatter signal from the at least one tag; and

communicating with the at least one tag in accordance with the determined identification information.

14. A localization method for use in a tag communication system, comprising:

associating a tag with an item;

reading a backscatter signal from the tag at a plurality of tag reader locations to provide a plurality of backscatter signals;

estimating a signal parameter of the backscatter signals of the plurality of backscatter signals to provide a plurality of derived signal parameters; and

localizing the item in accordance with the plurality of derived signal parameters.

15. The localization method for use in a tag communication system of claim 14, wherein the backscatter signals are read by a tag reader having a single antenna further comprising localizing the item in accordance with an antenna array technique performed upon the plurality of derived signal parameters.

16. The localization method for use in a tag communication system of claim 14, further comprising:

reading the backscatter signals with an antenna array to provide a further plurality of derived signal parameters for each tag reader location of the plurality of tag reader locations; and

localizing the item in accordance with the further pluralities of derived signal parameters.

17. The localization method for use in a tag communication system of claim 16, further comprising calibrating the plurality of derived signal parameters in accordance with the further pluralities of derived signal parameters.

18. The localization method for use in a tag communication system of claim 14, further comprising:

associating a supertag having a plurality of tags with the item;

reading backscatter signals from the tags of the plurality of tags to provide a further plurality of backscatter signals;

estimating a signal parameter of the backscatter signals of the further plurality of backscatter signals to provide a further plurality of derived signal parameters; and

localizing the item in accordance with the further plurality of derived signal parameters.

19. The localization method for use in a tag communication system of claim 14, wherein the tag is a marker tag further comprising determining a tag reader location in accordance with the plurality of signal parameters.

20. The localization method for use in a tag communication system of claim 19, further comprising determining a tag reader motion in accordance with the plurality of signal parameters.