Powering RFID tags using multiple synthesized-beam RFID readers

• US 9,373,012 B2
• Filed: 03/13/2014
• Issued: 06/21/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Pesavento, Alberto, Diorio, Christopher
• Primary Examiner(s): LY, TOAN C
• Application Number:
  US14/388,793
• Publication Number:
  US 20160042206A1
• Time in Patent Office: 831 Days
• Field of Search: 235/385, 235/439, 235/451
• US Class Current: 1/1
• CPC Class Codes: G06K 7/10158 methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
• CPC Class Codes: G06K 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: G06K 7/10297 arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 cryptographic protocols H04L9/00; network security protocols H04L63/00; real-time communication protocols in data switching networks H04L65/00; network protocols for data switching network services H04L67/00
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 21/061 Two dimensional planar arrays
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence

Abstract

Synthesized-beam RFID readers may be used to manage and provide information about RFID tag populations. In one embodiment, two or more synthesized-beam readers synthesize respective RF beams towards a tag location. The synthesized-beam readers may coordinate their pointing by means of a controller, a peer-to-peer network, or by using a master-slave arrangement. The synthesized-beam readers may coordinate their transmissions to increase the RF energy available to a tag at the pointing location.

Claims

1. A method for inventorying a Radio Frequency Identification (RFID) tag comprising:

communicating, from a controller, a target location to a first synthesized-beam RFID reader and to a second synthesized-beam RFID reader;

steering, responsive to the communicated target location, a first beam from the first synthesized-beam reader to the target location and a second beam from the second synthesized-beam reader to the target location;

transmitting, simultaneously, from the first synthesized-beam reader a modulated RF inventory signal and from the second synthesized-beam reader a substantially unmodulated RF signal;

receiving, responsive to the modulated RF inventory signal, a tag reply at one of the first and second synthesized-beam readers; and

transmitting, from one of the first and second synthesized-beam readers, a modulated RF acknowledgment signal responsive to the tag reply, and from the other of the first and second synthesized-beam readers a substantially unmodulated RF signal.

2. The method of claim 1, wherein the target location includes at least one of:

a beam indicator;

a floor location;

a Cartesian coordinate; and

a polar coordinate.

3. The method of claim 1, further comprising adjusting at least one of a power and a frequency of the RF signal from at least one of the first and second synthesized-beam readers to increase an inventory range of the RFID tag.

4. The method of claim 3, wherein the adjusting comprises sweeping over a range of values.

5. The method of claim 3, wherein the adjusting is adaptive and based on one or more of:

an environmental condition;

a received tag reply;

a tag performance characteristic; and

a tag population size.

6. The method of claim 1, further comprising steering the second beam to a plurality of locations in a vicinity of the target location.

7. The method of claim 1, further comprising synthesizing the second beam in response to at least one of:

determining that the first beam is an outer beam;

determining that a number of inventoried tags is less than an expected number; and

determining that the tag is moving toward a periphery of a field-of-view of the first synthesized-beam reader.

8. A method for inventorying a Radio Frequency Identification (RFID) tag comprising:

communicating, from a first synthesized-beam RFID reader, a target location to a second synthesized-beam RFID reader;

steering a first beam from the first synthesized-beam reader to the target location;

steering, responsive to the communicated target location, a second beam from the second synthesized-beam reader to the target location;

transmitting, simultaneously, from one of the first and second synthesized-beam readers a modulated RF inventory signal and from the other of the first and second synthesized-beam readers a substantially unmodulated RF signal;

receiving, responsive to the modulated RF inventory signal, a tag reply at one of the first and second synthesized-beam readers; and

transmitting, from one of the first and second synthesized-beam readers, a modulated RF acknowledgment signal responsive to the tag reply, and from the other of the first and second synthesized-beam readers a substantially unmodulated RF signal.

9. The method of claim 8, wherein the target location includes at least one of:

a beam indicator;

a floor location;

a Cartesian coordinate; and

a polar coordinate.

10. The method of claim 8, further comprising adjusting at least one of a power and a frequency of the RF signal from at least one of the first and second synthesized-beam readers to increase an inventory range of the RFID tag.

11. The method of claim 10, wherein the adjusting comprises sweeping over a range of values.

12. The method of claim 10, wherein the adjusting is adaptive and based on one or more of:

an environmental condition;

a received tag reply;

a tag performance characteristic; and

a tag population size.

13. The method of claim 8, further comprising steering the second beam to a plurality of locations in a vicinity of the target location.

14. The method of claim 8, further comprising synthesizing the second beam in response to at least one of:

determining that the first beam is an outer beam;

determining that a number of inventoried tags is less than an expected number; and

determining that the tag is moving toward a periphery of a field-of-view of the first synthesized-beam reader.

15. A method for inventorying a Radio Frequency Identification (RFID) tag comprising:

storing at least one target location and at least one corresponding target-location time in first and second synthesized-beam RFID readers;

steering, at the target-location time, a first beam from the first synthesized-beam reader to the target location and a second beam from the second synthesized-beam reader to the target location;

transmitting, simultaneously, from one of the first and second synthesized-beam readers a modulated RF inventory signal and from the other of the first and second synthesized-beam readers a substantially unmodulated RF signal;

receiving, responsive to the modulated RF inventory signal, a tag reply at one of the first and second synthesized-beam readers; and

transmitting, from one of the first and second synthesized-beam readers, a modulated RF acknowledgment signal responsive to the tag reply, and from the other of the first and second synthesized-beam readers a substantially unmodulated RF signal.

16. The method of claim 15, wherein the target location includes at least one of:

a beam indicator;

a floor location;

a Cartesian coordinate; and

a polar coordinate.

17. The method of claim 15, further comprising adjusting at least one of a power and a frequency of the RF signal from at least one of the first and second synthesized-beam readers to increase an inventory range of the RFID tag.

18. The method of claim 17, wherein the adjusting comprises at least one of:

sweeping over a range of values; and

adaptive adjustment based on one or more of an environmental condition, a received tag reply, a tag performance characteristic, and a tag population size.

19. The method of claim 15, further comprising coordinating the target-location time between the first and second synthesized-beam readers by at least one of:

a timer;

a trigger signal; and

a communication from one of the first and second synthesized-beam readers to the other of the first and second synthesized-beam readers.

20. The method of claim 15, further comprising steering the second beam to a plurality of locations in a vicinity of the target location at the target-location time.