Adjusting RFID waveform shape in view of detected RF energy

• US 7,408,466 B2
• Filed: 04/25/2006
• Issued: 08/05/2008
• 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): TRIEU, VAN THANH
• Application Number:
  US11/412,170
• Publication Number:
  US 20060261953A1
• Time in Patent Office: 833 Days
• Field of Search: 340/572.1, 340/572.2, 340/572.4, 340/568.1, 340/539.11, 340/539.13, 340/539.21, 340/10.1, 340/10.3, 340/10.33, 340/10.6, 235/375, 235/384, 235/435
• US Class Current: 340/572.2
• 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. 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,

apply a rule to RF energy that is detected in conjunction with using the selected channel for determining a result, and

adjust an own waveform shaping parameter according to the result, 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 transmitting 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 the waveform with a shape according to the adjusted own waveform shaping parameter are the first RF waves.

3. The system of claim 1, in which

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

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

measure a level of the RF energy, and

adjust the own waveform shaping parameter in accordance with the measured level.

5. The system of claim 1, in which the RF energy is received by the antenna.

6. The system of claim 1, in which the RF energy is received by a detector distinct from the antenna.

7. The system of claim 1, in which the RF energy is detected prior to frequency conversion.

8. The system of claim 1, in which the RF energy is detected after frequency conversion.

9. The system of claim 1, in which

the RF energy is detected prior to selecting the first communication channel.

10. The system of claim 1, in which

the RF energy is detected after selecting the first communication channel, but prior to transmitting the first RF waves.

11. The system of claim 1, in which

the RF energy is detected after transmitting the first RF waves.

12. The system of claim 1, further comprising:

an RF energy detector operable to detect the RF energy and output a measured value responsive to detecting, and

in which the waveform shaping parameter is adjusted according to the measured value.

13. The system of claim 1, in which the RF energy includes signal.

14. The system of claim 1, in which the RF energy includes noise.

15. The system of claim 1, in which the RF energy includes interference.

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

17. The system of claim 16, in which

applying the rule includes using a numerical parameter, and

updating includes changing the numerical parameter.

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

adjust a second own waveform shaping parameter responsive to the detected RF energy, at least some of the first and second RF waves having a waveform with a shape also according to the second adjusted own waveform shaping parameter.

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

then select a second one of the channels;

detect RF energy in conjunction with using the second channel;

compare the RF energies detected in conjunction with using the first and second channels; and

select one of the first and second channels depending on the comparison before the first RF waves are transmitted.

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

cause the antenna to transmit to the RFID tags third RF waves in the selected channel prior to adjusting the waveform shaping parameter, and

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

21. The system of claim 1, in which

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

22. The system of claim 1, in which

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

23. The system of claim 1, in which

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

24. The system of claim 23, 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.

25. 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.

26. The system of claim 25, in which

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

27. The system of claim 25, in which

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

28. 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 encountered in conjunction with using the selected channel;

applying means for applying a rule to the detected RF energy for determining a result,

adjusting means for adjusting an own waveform shaping parameter according to the result, 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 transmitting 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.

29. The system of claim 28, in which

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

30. The system of claim 28, in which

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

31. The system of claim 28, further comprising:

measuring means for measuring a level of the energy, and

in which the own waveform shaping parameter is adjusted in accordance with the measured energy level.

32. The system of claim 28, further comprising:

updating means for updating the rule.

33. The system of claim 32, in which

applying the rule includes using a numerical parameter, and

updating includes changing the numerical parameter.

34. 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 encountered in conjunction with using the selected channel;

applying a rule to the detected RF energy for determining a result,

adjusting an own waveform shaping parameter according to the result, 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 transmitting 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.

35. The article of claim 34, in which

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

36. The article of claim 34, in which

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

37. The article of claim 34, in which

the own waveform shaping parameter is adjusted in accordance with the measured level of the energy.

38. The article of claim 34, in which

the RF energy is detected prior to frequency conversion.

39. The article of claim 34, in which

the RF energy is detected after frequency conversion.

40. The article of claim 34, in which

the RF energy is detected prior to selecting the first communication channel.

41. The article of claim 34, in which

the RF energy is detected after selecting the first communication channel, but prior to transmitting the first RF waves.

42. The article of claim 34, in which

the RF energy is detected after transmitting the first RF waves.

43. The article of claim 34, in which when the instructions are executed, they further result in:

updating the rule.

44. The article of claim 43, in which

applying the rule includes using a numerical parameter, and

updating includes changing the numerical parameter.

45. 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 encountered in conjunction with using the selected channel;

applying a rule to the detected RF energy for determining a result,

adjusting an own waveform shaping parameter according to the result, 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 transmitting 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.

46. The method of claim 45, in which

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

47. The method of claim 45, in which

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

48. The method of claim 45, further comprising:

measuring a level of the energy, and

in which the own waveform shaping parameter is adjusted in accordance with the measured energy level.

49. The method of claim 45, in which the RF energy is detected prior to frequency conversion.

50. The method of claim 45, in which the RF energy is detected after frequency conversion.

51. The method of claim 45, in which the RF energy is detected prior to selecting the first communication channel.

52. The method of claim 45, in which the RF energy is detected after selecting the first communication channel, but prior to transmitting the first RF waves.

53. The method of claim 45, in which the RF energy is detected after transmitting the first RF waves.

54. The method of claim 45, in which the detected RF energy includes signal.

55. The method of claim 45, in which the detected RF energy includes noise.

56. The method of claim 45, in which the detected RF energy includes interference.

57. The method of claim 45, further comprising:

updating the rule.

58. The method of claim 57, in which

applying the rule includes using a numerical parameter, and

updating includes changing the numerical parameter.

59. The method of claim 45, further comprising:

adjusting a second own waveform shaping parameter responsive to the detected RF energy, at least some of the first and second RF waves having a waveform with a shape also according to the second adjusted own waveform shaping parameter.

60. The method of claim 45, further comprising:

then selecting a second one of the channels;

detecting RF energy encountered in conjunction with using the second channel;

comparing the RF energies detected in conjunction with using the first and the second channels; and

selecting one of the first and second channels depending on the comparison prior to transmitting the first RF waves.

61. The method of claim 45, further comprising:

causing the antenna to transmit to the RFID tags third RF waves in the selected channel prior to adjusting the waveform shaping parameter, and

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

62. The method of claim 45, in which

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

63. The method of claim 45, in which

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

64. The method of claim 45, in which

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

65. The method of claim 64, 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.

66. The method of claim 45, in which

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

67. The method of claim 66, in which

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

68. The method of claim 66, in which

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