RFID tags adjusting to different regulatory environments, and RFID readers to so adjust them and methods

• US 20050099270A1
• Filed: 11/10/2004
• Published: 05/12/2005
• Est. Priority Date: 11/10/2003
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Diorio, Christopher J., Sundstrom, Kurt E.
• Granted Patent: US 7,283,037 B2
• Time in Patent Office: Days
• US Class Current: 340/10.51
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

An RFID tag has an antenna to receive a configuration signal, and a circuit with a controller that can configure the RFID circuit responsive to the configuration signal. Configuring is such that the tag backscatters by impressing data either on the carrier frequency, or on a subcarrier in addition to the carrier signal, depending on the configuration signal. In the event of a subcarrier, the tag controller may optionally further determine a frequency of the subcarrier from the configuration signal. The tag may then be configured to backscatter differently, upon receiving a different configuration signal. A complementary reader transmits the configuration signal, thus imparting an operating parameter. The reader has an interface to receive an input indicative of a present geography, and a lookup table for determining an operating parameter based on the present geography. In one embodiment, the operating parameter is determined from regulations at that geographic location.

Claims

1. An RFID tag, comprising:

an antenna for receiving a first configuration signal and then a first carrier signal; and

a circuit coupled to the antenna, the circuit including a controller that is adapted to configure the tag to backscatter by impressing data on one of the carrier signal and a frequency of a first subcarrier in addition to the carrier signal, depending on the configuration signal.

2. The tag of claim 1, wherein

the controller is further adapted to determine the subcarrier frequency from the configuration signal.

3. The tag of claim 1, wherein

the antenna is adapted to receive a second configuration signal and then a second carrier signal, and

the controller is adapted to configure the tag to backscatter by impressing data on one of the second carrier signal and a frequency of the second subcarrier in addition to the second carrier signal, depending on the second configuration signal.

4. The tag of claim 3, wherein

the controller is further adapted to determine the second subcarrier frequency from the second configuration signal.

5. The tag of claim 1, wherein

the first configuration signal includes a first configuration parameter that can be used to determine at least one of a bit rate, cycles per symbol, subcarrier frequency, symbol assignment, and backscatter duration.

6. The tag of claim 1, wherein

the carrier signal has a frequency within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies wholly within the channel.

7. The tag of claim 1, wherein

the carrier signal has a frequency within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies that straddle a channel boundary.

8. The tag of claim 1, wherein

the carrier signal has a frequency within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies wholly outside the channel.

9. An RFID reader comprising:

an interface to receive an input indicative of a present geography;

a lookup table for determining an operating parameter based on the present geography; and

a controller adapted to transmit a first configuration signal for configuring RFID tags to operate at the operating parameter.

10. The RFID reader of claim 9, wherein

the operating parameter is one of at least one a bit rate, cycles per symbol, subcarrier frequency, symbol assignment, and backscatter duration.

11. The RFID reader of claim 9, wherein

the present regulatory environment specifies a frequency channel, and

the controller is adapted to transmit, after the first configuration signal, a carrier signal that has a carrier frequency with the channel.

12. The RFID reader of claim 11, wherein

the configuration signal commands the tag to backscatter data by modulating directly the carrier signal.

13. The RFID reader of claim 11, wherein

the configuration signal commands the tag to backscatter data by modulating a subcarrier frequency and the carrier signal.

14. The RFID reader of claim 13, wherein

the configuration signal also informs of the subcarrier frequency.

15. The RFID reader of claim 13, wherein

the data is backscattered at frequencies wholly within the channel.

16. The RFID reader of claim 13, wherein

the data is backscattered at frequencies that straddle a boundary of the channel.

17. The RFID reader of claim 13, wherein

the data is backscattered at frequencies wholly outside the channel.

18. The RFID reader of claim 9, wherein

the interface is a user interface, and

the input is received manually by a user.

19. The RFID reader of claim 9, wherein

the interface is an a computer system, and

the input is received by an operator of the computer system.

20. The RFID reader of claim 9, wherein

the interface is a network interface to a computer system, and

the input is received via a network from the computer system.

21. The RFID reader of claim 9, wherein

the input is a signal received from another RFID reader.

22. The RFID reader of claim 9, wherein

the input is RF interference, and

the operating parameter is looked up from the RF interference.

23. The RFID reader of claim 9, wherein

the operating parameter is found from known a regulation that is enforced at the geography.

24. The RFID reader of claim 9, wherein

the interface is a global positioning system (GPS) interface, and

the input is a signal identifying a geographic location at which the RFID reader is operating.

25. An RFID tag including:

means for receiving a first configuration signal and then a first carrier signal; and

means for backscattering by impressing data on one of a frequency of the carrier signal and a frequency of a first subcarrier in addition to the carrier signal, depending on the configuration signal.

26. The tag of claim 25, further comprising:

means for determining the subcarrier frequency from the configuration signal.

27. A method for an RFID circuit comprising:

receiving a first configuration signal and then a first carrier signal; and

then backscattering by impressing data on one of a frequency of the carrier signal and a frequency of a first subcarrier in addition to the carrier signal, depending on the configuration signal.

28. The method of claim 27, further comprising:

determining the subcarrier frequency from the configuration signal.

29. The method of claim 27, further comprising:

receiving a second configuration signal and then a second carrier signal; and

then backscattering by impressing data on one of a frequency of the second carrier signal and a frequency of a second subcarrier in addition to the second carrier signal, depending on the second configuration signal.

30. The method of claim 29, further comprising:

determining the second subcarrier frequency from the second configuration signal.

31. The method of claim 27, wherein

the first configuration signal includes a first configuration parameter that can be used to determine at least one of a bit rate, cycles per symbol, subcarrier frequency, symbol assignment, and backscatter duration.

32. The method of claim 27, further comprising:

configuring a modulator that performs the backscattering.

33. The method of claim 32, wherein

configuring of the modulator includes modifying a modulator switch signal that is supplied to the modulator.

34. The method of claim 27, wherein

the carrier frequency signal is within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies wholly within the channel.

35. The method of claim 27, wherein

the carrier frequency signal is within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies that straddle a channel boundary.

36. The method of claim 27, wherein

the carrier frequency signal is within a frequency channel specified by a regulation, and

the subcarrier frequency is such that data is backscattered at frequencies wholly outside the channel.