Performance driven adjustment of RFID waveform shape

• US 7,391,329 B2
• Filed: 04/25/2006
• Issued: 06/24/2008
• 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): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US11/412,172
• Publication Number:
  US 20060261955A1
• Time in Patent Office: 791 Days
• Field of Search: 340/572.4, 340/572.1, 340/572.2, 340/10.1, 340/10.3, 340/10.4, 340/10.5, 340/825.69, 340/825.72, 702/107, 331/175
• 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 and used to adjust a waveform shaping parameter in combination with a performance requirement. 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;

input a performance requirement;

adjust an own waveform shaping parameter responsive to RF energy that is detected in conjunction with using the selected channel and also responsive to the performance requirement; 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 own waveform shaping parameter is adjusted also responsive to RF energy detected in conjunction with using the selected channel.

12. The system of claim 11, in which

the processing block is further operable to cause the antenna to transmit to the RFID tags third RF waves prior to adjusting the own waveform shaping parameter, and

the RF energy is detected after transmitting the third waves.

13. The system of claim 1, in which

the performance requirement is one of a maximum error rate, a minimum tag throughput rate, and a minimum signal degradation amount.

14. The system of claim 1, in which

the performance requirement is a time statistic to successfully read one or all of the tags.

15. The system of claim 1, in which

the performance requirement is expressed in terms of a probability.

16. The system of claim 1, in which the processing block is further operable to

propose a value for the own waveform shaping parameter;

estimate a compliance probability of whether the proposed value will cause the performance requirement to be met; and

adopt the proposed value only if the compliance probability exceeds a confidence threshold.

17. The system of claim 1,

in which the performance requirement is expressed in terms of a metric, and

further comprising:

computing a value for the own waveform shaping parameter that would result in performance in which the metric is optimized; and

adopting the computed value.

18. The system of claim 1, in which

the performance requirement constrains a choice for the waveform shaping parameter.

19. The system of claim 18, in which

the constrained choice is that of signal encoding.

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

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

inputting means for inputting a performance requirement;

adjusting means for adjusting an own waveform shaping parameter responsive to the performance requirement; 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 the second RF waves having a waveform with a shape according to the adjusted own waveform shaping parameter.

21. The system of claim 20, in which

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

22. The system of claim 20, in which

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

23. The system of claim 20, in which

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

24. The system of claim 20, in which

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

25. The system of claim 20, in which

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

26. The system of claim 20, in which

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

27. The system of claim 20, further comprising:

detecting means for detecting RF energy in conjunction with using the selected channel, and

in which the own waveform shaping parameter is adjusted also responsive to the detected RF energy.

28. The system of claim 27, in which

prior to adjusting the own waveform shaping parameter, third RF waves are transmitted to the RFID tags, and

the RF energy is detected after transmitting the third waves.

29. The system of claim 20, in which

the performance requirement is one of a maximum error rate, a minimum tag throughput rate, and a minimum signal degradation amount.

30. The system of claim 20, in which

the performance requirement is a time statistic to successfully read one or all of the tags.

31. The system of claim 20, in which

the performance requirement is expressed in terms of a probability.

32. The system of claim 20, further comprising:

proposing means for proposing a value for the own waveform shaping parameter;

estimating means for estimating a compliance probability of whether the proposed value will cause the performance requirement to be met; and

adopting means for adopting the proposed value only if the compliance probability exceeds a confidence threshold.

33. The system of claim 20,

in which the performance requirement is expressed in terms of a metric, and

further comprising:

computing means for computing a value for the own waveform shaping parameter that would result in performance in which the metric is optimized; and

adopting means for adopting the computed value.

34. The system of claim 20, in which

the performance requirement constrains a choice for the waveform shaping parameter.

35. The system of claim 34, in which

the constrained choice is that of signal encoding.

36. 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;

inputting a performance requirement;

adjusting an own waveform shaping parameter responsive to the performance requirement; 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.

37. The article of claim 36, in which

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

38. The article of claim 36, in which

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

39. The article of claim 36, in which

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

40. The article of claim 36, in which

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

41. The article of claim 36, in which

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

42. The article of claim 41, 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.

43. The article of claim 36, in which

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

44. The article of claim 43, in which

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

45. The article of claim 43, in which

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

46. The article of claim 36, in which when the instructions are executed, they further result in:

detecting RF energy in conjunction with using the selected channel, and

in which the own waveform shaping parameter is adjusted also responsive to the detected RF energy.

47. The article of claim 46, in which when the instructions are executed, they further result in:

prior to adjusting the own waveform shaping parameter, transmitting to the RFID tags third RF waves, and

in which the RF energy is detected after transmitting the third waves.

48. The article of claim 36, in which

the performance requirement is one of a maximum error rate, a minimum tag throughput rate, and a minimum signal degradation amount.

49. The article of claim 36, in which

the performance requirement is a time statistic to successfully read one or all of the tags.

50. The article of claim 36, in which

the performance requirement is expressed in terms of a probability.

51. The article of claim 36, in which when the instructions are executed, they further result in:

proposing a value for the own waveform shaping parameter;

estimating a compliance probability of whether the proposed value will cause the performance requirement to be met; and

adopting the proposed value only if the compliance probability exceeds a confidence threshold.

52. The article of claim 36, in which

the performance requirement is expressed in terms of a metric, and

when the instructions are executed, they further result in:

computing a value for the own waveform shaping parameter that would result in performance in which the metric is optimized; and

adopting the computed value.

53. The article of claim 36, in which

the performance requirement constrains a choice for the waveform shaping parameter.

54. The article of claim 53, in which

the constrained choice is that of signal encoding.

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

selecting a first one of a plurality of communication channels;

inputting a performance requirement;

adjusting an own waveform shaping parameter responsive to the performance requirement; 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.

56. The method of claim 55, in which

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

57. The method of claim 55, in which

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

58. The method of claim 55, in which

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

59. The method of claim 55, in which

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

60. The method of claim 55, in which

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

61. The method of claim 60, 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.

62. The method of claim 55, in which

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

63. The method of claim 62, in which

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

64. The method of claim 62, in which

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

65. The method of claim 55, further comprising:

detecting RF energy in conjunction with using the selected channel, and

in which the own waveform shaping parameter is adjusted also responsive to the detected RF energy.

66. The method of claim 65, further comprising:

prior to adjusting the own waveform shaping parameter, transmitting to the RFID tags third RF waves, and

in which the RF energy is detected after transmitting the third waves.

67. The method of claim 55, in which

the performance requirement is one of a maximum error rate, a minimum tag throughput rate, and a minimum signal degradation amount.

68. The method of claim 55, in which

the performance requirement is a time statistic to successfully read one or all of the tags.

69. The method of claim 55, in which

the performance requirement is expressed in terms of a probability.

70. The method of claim 55, further comprising:

proposing a value for the own waveform shaping parameter;

estimating a compliance probability of whether the proposed value will cause the performance requirement to be met; and

adopting the proposed value only if the compliance probability exceeds a confidence threshold.

71. The method of claim 55,

in which the performance requirement is expressed in terms of a metric, and further comprising:

computing a value for the own waveform shaping parameter that would result in performance in which the metric is optimized; and

adopting the computed value.

72. The method of claim 55, in which

the performance requirement constrains a choice for the waveform shaping parameter.

73. The method of claim 72, in which

the constrained choice is that of signal encoding.