Adjusting RFID waveform shape in view of signal from another reader

• US 7,436,308 B2
• Filed: 04/25/2006
• Issued: 10/14/2008
• Est. Priority Date: 04/13/2004
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Diorio, Christopher J., Sundstrom, Kurt E., Dietrich, Paul, Humes, Todd E.
• Primary Examiner(s): Hofsass; Jeff
• Assistant Examiner(s): Yacob; Sisay
• Application Number:
  US11/412,192
• Publication Number:
  US 20060261956A1
• Time in Patent Office: 903 Days
• Field of Search: 340/572.4, 340/572.1, 340/10.1, 340/825.69, 340/568.1, 340/10.3, 331/175, 455/106, 455/108, 455/189.1, 702/107
• US Class Current: 340/572.4
• 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

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 another RFID reader. 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 RF energy detected within the selected channel as a reader system signal from another RFID reader system;

decode the identified reader system signal;

adjust an own waveform shaping parameter responsive to the decoded reader system signal; and

cause the antenna to transmit to 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 operational processing block is further operable to interpret an other waveform shaping parameter from the decoded reader system signal, and

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

12. The system of claim 11, in which

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

13. The system of claim 11, in which

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

14. The system of claim 13, in which

the other 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 width, and a preamble.

15. The system of claim 11, in which

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

16. The system of claim 15, in which

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

17. The system of claim 15, in which

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

18. The system of claim 11, in which

the other waveform shaping parameter includes an interpreted Q parameter suitable for controlling how an RFID tag generates a random number during an inventorying session, and

the own waveform shaping parameter encodes a transmitted Q parameter whose value is determined from a value of the interpreted Q parameter.

19. The system of 18 in which

the value of the transmitted Q parameter is the equal to that of the interpreted Q parameter.

20. The system of 18 in which

the other waveform shaping parameter does not include a corresponding ACK command, and

the transmitted Q parameter has value of zero.

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

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

detecting means for detecting RF energy within the selected channel;

identifying means for identifying the detected RF energy as a reader system signal from another RFID reader system;

decoding means for decoding the identified reader system signal;

adjusting means for adjusting an own waveform shaping parameter responsive to the decoded reader system signal; and

antenna means for transmitting to the RFID tags first RF waves in the selected channel and for 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 second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

22. The system of claim 21, in which

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

23. The system of claim 21, in which

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

24. The system of claim 21, in which

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

25. The system of claim 21, in which

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

26. The system of claim 21, in which

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

27. The system of claim 21, further comprising:

interpreting means for interpreting from the decoded reader system signal 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 27, in which

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

29. The system of claim 28, in which

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

30. The system of claim 28, in which

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

31. The system of claim 27, in which

the other waveform shaping parameter includes an interpreted Q parameter suitable for controlling how an RFID tag generates a random number during an inventorying session, and

the own waveform shaping parameter encodes a transmitted Q parameter whose value is determined from a value of the interpreted Q parameter.

32. 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;

detecting RF energy within the selected channel;

identifying the detected RF energy as a reader system signal from another RFID reader system;

decoding the identified reader system signal;

adjusting an own waveform shaping parameter responsive to the decoded reader system signal; 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 second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

33. The article of claim 32, in which

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

34. The article of claim 32, in which

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

35. The article of claim 32, in which

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

36. The article of claim 32, in which

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

37. The article of claim 32, in which

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

38. The article of claim 37, 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.

39. The article of claim 32, in which

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

40. The article of claim 39, in which

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

41. The article of claim 39, in which

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

42. The article of claim 32, in which when the instructions are executed, they further result in:

interpreting from the decoded reader system signal an other waveform shaping parameter, and

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

43. The article of claim 42, in which

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

44. The article of claim 42, in which

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

45. The article of claim 44, in which

the other 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 width, and a preamble.

46. The article of claim 42, in which

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

47. The article of claim 46, in which

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

48. The article of claim 46, in which

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

49. The article of claim 42, in which

the other waveform shaping parameter includes an interpreted Q parameter suitable for controlling how an RFID tag generates a random number during an inventorying session, and

the own waveform shaping parameter encodes a transmitted Q parameter whose value is determined from a value of the interpreted Q parameter.

50. The article of claim 49, in which

the value of the transmitted Q parameter is the equal to that of the interpreted Q parameter.

51. The article of claim 49, in which

the other waveform shaping parameter does not include a corresponding ACK command, and

the transmitted Q parameter has value of zero.

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

selecting a first one of a plurality of communication channels;

detecting RF energy within the selected channel;

identifying the detected RF energy as a reader system signal from another RFID reader system;

decoding the identified reader system signal;

adjusting an own waveform shaping parameter responsive to the decoded reader system signal; 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 second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

53. The method of claim 52, in which

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

54. The method of claim 52, in which

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

55. The method of claim 52, in which

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

56. The method of claim 52, in which

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

57. The method of claim 52, in which

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

58. The method of claim 57, 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.

59. The method of claim 52, in which

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

60. The method of claim 59, in which

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

61. The method of claim 59, in which

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

62. The method of claim 52, further comprising:

interpreting from the decoded reader system signal an other waveform shaping parameter, and

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

63. The method of claim 62, in which

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

64. The method of claim 62, in which

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

65. The method of claim 64, in which

the other 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 width, and a preamble.

66. The method of claim 62, in which

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

67. The method of claim 66, in which

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

68. The method of claim 66, in which

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

69. The method of claim 62, in which

the other waveform shaping parameter includes an interpreted Q parameter suitable for controlling how an RFID tag generates a random number during an inventorying session, and

the own waveform shaping parameter encodes a transmitted Q parameter whose value is determined from a value of the interpreted Q parameter.

70. The method of 69 in which

the value of the transmitted Q parameter is the equal to that of the interpreted Q parameter.

71. The method of 69 in which

the other waveform shaping parameter does not include a corresponding ACK command, and

the transmitted Q parameter has value of zero.