Positioning Guidance for Increasing Reliability of Near-Field Communications

• US 20130084801A1
• Filed: 09/30/2011
• Published: 04/04/2013
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: ROYSTON, Philip Stewart, COX, David
• Granted Patent: US 9,152,832 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: G06K 7/015 Aligning or centering of the sensing device with respect to the record carrier
• CPC Class Codes: G06K 7/10118 the sensing being preceded by at least one preliminary step
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/73 for taking measurements, e.g. using sensing coils

Abstract

To promote ease of use, as well as a reduction in bit error rates during extended data exchange between a coupled NFC tag/reader pair, signal strength is measured from a plurality of NFC tag antennas each positioned differently with respect to a common reader field, and differences in signal strength are used to determine an optimum positioning of the tag, or tag emulator, with respect to the reader. Alternative embodiments may include signal time of flight for determining orientation of the NFC antennas within the reader field. Information is generated by the tag, or tag emulator, and output by the tag, or tag emulator, such that a user may direct the positioning of the tag, or tag emulator, for improved communication with the reader.

Claims

1. A method of operating an NFC-enabled device, comprising:

a) detecting, by the NFC-enabled device, a respective current in each of a plurality of NFC antennas in an NFC antenna array, the respective currents induced by a common NFC reader field; and

b) determining, based at least in part on the magnitude of each of the respective currents, if changing the position of the NFC-enabled device would improve communicative interaction with the NFC reader field;

wherein the NFC antenna array is disposed on the NFC-enabled device.

2. The method of claim 1, further comprising:

(c) generating, if the determination of (b) is affirmative, position-correction information.

3. The method of claim 2, further comprising:

(d) providing user-perceivable information based on the position-correction information.

4. The method of claim 3, further comprising:

(e) repeating steps (a) through (d).

5. The method of claim 4, wherein each of the plurality of NFC antennas nominally has the same shape and dimensions.

6. The method of claim 4, wherein each of the plurality of NFC antennas nominally has the same material composition.

7. The method of claim 4, wherein the position-correction information comprises information representing how far the center of the NFC antenna array should be moved in an x direction and a y direction to align the NFC antenna array to the reader field.

8. The method of claim 3, wherein the user-perceivable information comprises a visual display representing the distance and direction to move the NFC-enabled device in order to align the NFC antenna array with the reader field.

9. The method of claim 8, wherein aligning the NFC antenna array with the reader field comprises centering the NFC antenna array within the reader field.

10. The method of claim 8, wherein aligning the NFC antenna array with the reader field comprises positioning the NFC antenna array within the reader field to obtain an increased level of coupling between the reader field and the NFC antenna array.

11. A method of operating an NFC tag emulator, comprising:

coupling to an NFC reader field at each of a plurality of NFC antennas, each of the plurality of NFC antennas disposed on the tag emulator;

determining, by the tag emulator, the relative coupling strength at each of the plurality of antennas based at least in part on the magnitude of a current induced in each of the plurality of antennas by the coupled NFC reader field;

generating, by the tag emulator, position-correction information based at least in part on the relative coupling strength at each of the plurality of antennas;

wherein each of the plurality of antennas has a known spaced apart relationship to the other antennas of the plurality of antennas.

12. The method of claim 11, wherein each of the of the plurality of antennas nominally has the same physical dimensions.

13. The method of claim 11, wherein at least one of the plurality of antennas has dimensions that are different from the dimensions of the other antennas of the plurality of antennas.

14. The method of claim 11, wherein the plurality of antennas are co-planar.

15. The method of claim 11, wherein determining the relative strength and generating the position-correction information are performed by computational resources disposed on the tag emulator.

16. An NFC-enabled device, comprising:

an NFC antenna array having at least three antennas;

a plurality of field strength detector circuits, one field strength detector circuit coupled to each of the at the least three antennas, the field strength detector circuits operable to provide one or more signals indicative of the strength of the received signal at the antenna to which it is coupled;

a computational resource coupled to each of the plurality of field strength detectors, the computational resource operable, based at least in part on the signals indicative of the strength of the received signal at each antenna of the NFC antenna array, to determine whether the NFC-enabled device should be repositioned for improved communicative interaction with a reader device; and

a visual display device coupled to the computational resource;

wherein the visual display, under control of the computational resource, provides a user-perceivable output indicating the distance and direction for repositioning the NFC-enabled device.

17. The NFC-enabled device of claim 16, wherein the at least three antennas are coplanar with each other.

18. The NFC-enabled device of claim 16, wherein each of the at least three antennas nominally have the same shape and dimensions.

19. The NFC-enabled device of claim 16, wherein each of the at least three antennas nominally comprise the same materials.

20. The NFC-enabled device of claim 18, wherein each of the at least three antennas positioned symmetrically with respect to each other.

21. A method of aligning a pair of NFC-enabled devices to each other, at least one of the NFC-enabled devices having a plurality of antennas, comprising:

transmitting from each of the plurality of antennas of a first one of the pair of NFC-enabled devices, a corresponding command;

receiving a response to each of the commands;

measuring the response delay time of each of the responses;

recording each response delay time such that each response delay time is associated with the antenna from which the respective command was transmitted; and

determining the distance of each of the antennas from the source of the response based on the response delay time associated with each antenna;

wherein the response delay time is the amount of time between the command sent and the reception of a first response edge.

22. The method of claim 21, wherein the first response edge is carrier modulation.

23. The method of claim 21, wherein the first response edge is load modulation.

24. A method of aligning a pair of NFC-enabled devices to each other, at least one of the NFC-enabled devices having a plurality of antennas, comprising:

transmitting a plurality of commands from each of the plurality of antennas of a first one of the pair of NFC-enabled devices;

receiving a response to each of the commands;

measuring the response delay time of each of the responses;

recording each response delay time such that each response delay time is associated with the antenna from which the respective command was transmitted;

averaging, for each of the plurality of antennas, the associated plurality of response delay times; and

determining the distance of each of the antennas from the source of the response based on the average response delay time associated with each antenna;

wherein the response delay time is the amount of time between the command sent and the reception of a first response edge.