Adjusting RFID waveform shape in view of signal from an RFID tag

• US 20060261952A1
• Filed: 04/25/2006
• Published: 11/23/2006
• Est. Priority Date: 04/13/2004
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Diorio, Christopher J., Sundstrom, Kurt E., Kavounas, Gregory T., Dietrich, Paul, Humes, Todd E.
• Granted Patent: US 7,417,548 B2
• Time in Patent Office: Days
• US Class Current: 340/572.200
• 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
• 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

Abstract

Systems, software, devices, and methods are described for an RFID reader system to communicate with RFID tags. RF energy encountered in conjunction with using a selected channel is detected. The RF energy can be a signal from an RFID tag. The detected signal is used to adjust a waveform shaping parameter. RF waves can be transmitted from the reader to the RFID tags and RF waves can be backscattered from the RFID tags. At least some of the RF waves transmitted to or backscattered from the RFID tags have a waveform with a shape according to the adjusted waveform shaping parameter.

Claims

1. An RFID reader system comprising:

an antenna; and

an operational processing block coupled to the antenna and operable to

select a first one of a plurality of communication channels;

identify fourth RF waves receive in the selected channel as backscatter from the RFID tags;

decode the tag backscatter;

adjust an own waveform shaping parameter responsive to the decoded tag backscatter; and

cause the antenna to transmit to the RFID tags first RF waves in the selected channel such that second RF waves are backscattered from the RFID tags in response to the first RF waves, in which at least some of one of the first RF waves and the second RF waves have a waveform with a shape according to the adjusted own waveform shaping parameter.

2. The system of claim 1, in which

the RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter are the first waves.

3. The system of claim 1, in which

the RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter are the second waves.

4. The system of claim 1, in which

the own waveform shaping parameter controls a choice of a modulation format.

5. The system of claim 1, in which

the own waveform shaping parameter controls a choice of a preamble.

6. The system of claim 1, in which

the own waveform shaping parameter controls a choice of a signal encoding.

7. The system of claim 6, in which

the own waveform shaping parameter communicates one or a combination:

of a data rate, a mode, attributes of a calibration pulse, a rise time, a fall time, a pulse shaping, a pulse width, and a preamble.

8. The system of claim 1, in which

the own waveform shaping parameter represents a protocol parameter for an RFID system according to a communications protocol.

9. The system of claim 8, in which

the protocol parameter includes a command for a tag to change its state machine.

10. The system of claim 8, in which

the protocol parameter includes a command for a tag to respond in a certain manner according to the protocol.

11. The system of claim 1, in which

the processing block is further operable to cause the antenna to transmit third RF waves, and

in which the fourth RF waves are received in response to transmitting the third RF waves.

12. The system of claim 1, in which

the operational processing block is further operable to interpret an other waveform shaping parameter from the decoded tag backscatter, and

the own waveform shaping parameter is adjusted responsive to the other waveform shaping parameter.

13. The system of claim 1, in which

the fourth RF waves are received from.RFID tags without the processing block having caused the fourth RF waves to be transmitted, and

the processing block is further operable to

error-check to discern a possible error in the tag backscatter of the fourth RF waves, and

in which the waveform shaping parameter is adjusted responsive to whether an error was discerned.

14. The system of claim 13, in which

error-checking includes comparing an amplitude of a received waveform segment with a first threshold and a second threshold, and

an error is discerned if the amplitude is between the first and second thresholds.

15. The system of claim 13, in which the operational processing block is further operable to

interpret an other waveform shaping parameter from the decoded tag backscatter, and

in which error-checking is performed on the other waveform shaping parameter.

16. The system of claim 13, in which

the tag backscatter of the fourth RF waves encodes a group of symbols, and

an error is discerned if a redundant one of the symbols does not meet a condition with respect to others of the symbols.

17. The system of claim 13, in which the processing block is further operable to update an error count in response to discerning an error, and

in which the waveform shaping parameter is adjusted responsive to whether the error count exceeds an error threshold.

18. An RFID reader system operable to communicate with RFID tags, comprising:

selecting means for selecting a first one of a plurality of communication channels;

antenna means for receiving fourth RF waves in the selected channel;

identifying means for identifying the fourth RF waves as backscatter from the RFID tags;

decoding means for decoding the tag backscatter; and

adjusting means for adjusting an own waveform shaping parameter responsive to the decoded tag backscatter, and

in which the antenna means is further operable to transmit to the RFID tags first RF waves in the selected channel and receive second RF waves backscattered from the RiGID tags in response to the first RF waves, at least some of one of the first and the second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

19. The system of claim 18, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the first waves.

20. The system of claim 18, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the second waves.

21. The system of claim 18, in which

the own waveform shaping parameter controls a choice of a modulation format.

22. The system of claim 18, in which

the own waveform shaping parameter controls a choice of a preamble.

23. The system of claim 18, in which

the own waveform shaping parameter represents a protocol parameter for an RFID system according to a communications protocol.

24. The system of claim 23, in which

the protocol parameter includes a command for a tag to change its state machine.

25. The system of claim 23, in which

the protocol parameter includes a command for a tag to respond in a certain manner according to the protocol.

26. The system of claim 18, in which

the antenna means is operable to transmit to the RFID tags third RF waves, and

in which the fourth RF waves are received in response to transmitting the third RF waves.

27. The system of claim 18, further comprising:

means for interpreting from the tag backscatter an other waveform shaping parameter, and

in which the own waveform shaping parameter is adjusted responsive to the other waveform shaping parameter.

28. The system of claim 18,

in which the fourth RF waves are received from RFID tags without having caused the fourth RF waves to be transmitted;

and further comprising;

error-checking means for error-checking to discern a possible error in the tag backscatter, and

in which the waveform shaping parameter is adjusted responsive to whether an error was discerned.

29. An article comprising:

a storage medium, the storage medium having instructions stored thereon, in which when the instructions are executed by at least one component of an RFID reader system that is operable to communicate with RFID tags, they result in;

selecting a first one of a plurality of communication channels;

receiving fourth RF waves in the selected channel;

identifying the fourth RF waves as backscatter from the RFID tags;

decoding the tag backscatter;

adjusting an own waveform shaping parameter responsive to the decoded tag backscatter; and

transmitting to the RFID tags first RF waves in the selected channel and receiving second RF waves backscattered from the RFID tags in response to the first RF waves, at least some of one of the first and the second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

30. The article of claim 29, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the first waves.

31. The article of claim.29, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the second waves.

32. The article of claim 29, in which

the own waveform shaping parameter controls a choice of a modulation format.

33. The article of claim 29, in which

the own waveform shaping parameter controls a choice of a preamble.

34. The article of claim 29, in which

the own waveform shaping parameter controls a choice of a signal encoding.

35. The article of claim 34, in which

the own waveform shaping parameter communicates one or a combination:

of a data rate, a mode, attributes of a calibration pulse, a rise time, a fall time, a pulse shaping, a pulse width, and a preamble.

36. The article of claim 29, in which

the own waveform shaping parameter represents a protocol parameter for an RFID system according to a communications protocol.

37. The article of claim 36, in which

the protocol parameter includes a command for a tag to change its state machine.

38. The article of claim 36, in which

the protocol parameter includes a command for a tag to respond in a certain manner according to the protocol.

39. The article of claim 29, in which when the instructions are executed, they further result in:

transmitting to the RFID tags third RF waves, and

in which the fourth RF waves are received in response to transmitting the third RF waves.

40. The article of claim 29, in which when the instructions are executed, they further result in:

interpreting from the tag backscatter an other waveform shaping parameter, and

in which the own waveform shaping parameter is adjusted responsive to the other waveform shaping parameter.

41. The article of claim 29, in which

the fourth RF waves are received from RFID tags without having caused the fourth RF waves to be transmitted, and

when the instructions are executed, they further result in:

error-checking to discern a possible error in the tag backscatter, and

in which the waveform shaping parameter is adjusted responsive to whether an error was discerned.

42. The article of claim 41, in which

error-checking includes comparing an amplitude of a received waveform segment with a first threshold and a second threshold, and

an error is discerned if the amplitude is between the first and second thresholds.

43. The article of claim 41, in which when the instructions are executed, they further result in:

interpreting an other waveform shaping parameter from the decoded tag backscatter, and

in which error-checking is performed on the other waveform shaping parameter.

44. The article of claim 41, in which

the tag backscatter of the fourth RF waves includes a group of symbols, and

an error is discerned if a redundant one of the symbols does not meet a condition with respect to others of the symbols.

45. The article of claim 41, in which when the instructions are executed, they further result in:

updating an error count in response to discerning an error, and

in which the own waveform shaping parameter is adjusted responsive to whether the error count exceeds an error threshold.

46. A method for an RFID reader system to communicate with RFID tags, comprising:

selecting a first one of a plurality of communication channels;

receiving fourth RF waves in the selected channel;

identifying the fourth RF waves as backscatter from the RFID tags;

decoding the tag backscatter;

adjusting an own waveform shaping parameter responsive to the decoded tag backscatter; and

transmitting to the RFID tags first RF waves in the selected channel and receiving second RF waves backscattered from the RFID tags in response to the first RF waves, at least some of one of the first and the second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

47. The method of claim 46, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the first waves.

48. The method of claim 46, in which

the RF waves having a waveform with a shape according to the adjusted waveform shaping parameter are the second waves.

49. The method of claim 46, in which

the own waveform shaping parameter controls a choice of a modulation format.

50. The method of claim 46, in which

the own waveform shaping parameter controls a choice of a preamble.

51. The method of claim 46, in which

the own waveform shaping parameter controls a choice of a signal encoding.

52. The method of claim 51, in which

the own waveform shaping parameter communicates one or a combination:

of a data rate, a mode, attributes of a calibration pulse, a rise time, a fall time, a pulse shaping, a pulse width, and a preamble.

53. The method of claim 46, in which

the own waveform shaping parameter represents a protocol parameter for an RFID system according to a communications protocol.

54. The method of claim 53, in which

the protocol parameter includes a command for a tag to change its state machine.

55. The method of claim 53, in which

the protocol parameter includes a command for a tag to respond in a certain manner according to the protocol.

56. The method of claim 46, further comprising:

transmitting to the RFID tags third RF waves, and

in which the fourth RF waves are received in response to transmitting the third RF waves.

57. The method of claim 46, further comprising:

interpreting from the tag backscatter an other waveform shaping parameter, and

in which the own waveform shaping parameter is adjusted responsive to the other waveform shaping parameter.

58. The method of claim 46,

in which the fourth RF waves are received from RFID tags without having caused the fourth RF waves to be transmitted;

and further comprising;

error-checking to discern a possible error in the tag backscatter, and

in which the waveform shaping parameter is adjusted responsive to whether an error was discerned.

59. The method of claim 58, in which

error-checking includes comparing an amplitude of a received waveform segment with a first threshold and a second threshold, and

an error is discerned if the amplitude is between the first and second thresholds.

60. The method of claim 58, further comprising:

interpreting an other waveform shaping parameter from the decoded tag backscatter, and

in which error-checking is performed on the other waveform shaping parameter.

61. The method of claim 58, in which

the tag backscatter of the fourth RF waves includes a group of symbols, and

an error is discerned if a redundant one of the symbols does not meet a condition with respect to others of the symbols.

62. The method of claim 58, further comprising:

updating an error count in response to discerning an error, and

in which the own waveform shaping parameter is adjusted responsive to whether the error count exceeds an error threshold.