RFID Communication System and Method of Operation

• US 20080180253A1
• Filed: 07/23/2007
• Published: 07/31/2008
• Est. Priority Date: 04/24/1998
• Status: Abandoned Application

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Ovard, David K., Greeff, Roy
• Application Number:
  US11/781,884
• Publication Number:
  US 20080180253A1
• Time in Patent Office: Days
• 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
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/22 Scatter propagation systems , e.g. ionospheric, tropospheric or meteor scatter
• CPC Class Codes: H04J 13/0022 PN, e.g. Kronecker

Abstract

A radio frequency identification (RFID) system enabling backscatter communication between a reader and a tag. A baseband data signal is encoded, and it may be selectively inverted and used to modulate a carrier using amplitude modulation, phase modulation, or both amplitude and phase modulation. A reply received from the tag in response to a command from the reader may include an identification code associated with an object to which the tag is affixed.

Claims

1-47. -47. (canceled)

48. :

A method of communicating between a radio frequency identification (RFID) reader and at least one RFID tag, the method comprising;

providing an RFID tag, the RFID tag comprising an antenna and a single monolithic integrated circuit coupled to the antenna and configured to modulate an impedance of the antenna to enable backscatter communication with the RFID reader, the integrated circuit having stored therein an identification code;

encoding a baseband data signal to generate an encoded data signal wherein a data bit zero of the baseband data signal is represented by both logic high and logic low levels in the encoded data signal and a data bit one of the baseband data signal is represented by both logic high and logic low levels in the encoded data signal, the baseband data signal comprising a command;

transmitting the command from the RFID reader, including both amplitude and phase modulating a carrier wave using the encoded data signal;

transmitting, from the RFID reader, the carrier wave as a continuous wave after transmitting the command; and

receiving a reply, including the identification code, from the RFID tag in response to the command, the reply comprising backscatter modulation of the carrier wave.

49. :

The method of claim 48, wherein transmitting the command from the RFID reader is done in accordance with an application program executing on a host computer to which the RFID reader is coupled, and the RFID reader communicates the received identification code to the host computer.

50. :

The method of claim 48, further comprising providing power to the RFID tag from a battery.

51. :

The method of claim 48, wherein the impedance of the antenna is configured to be modulated by shorting together and isolating from each other two halves of a dipole antenna.

52. :

The method of claim 48, further comprising band limiting the encoded data signal before using the encoded data signal to modulate the carrier wave.

53. :

The method of claim 48, wherein the data bit zero of the baseband data signal is represented by a plurality of logic high levels in the encoded data signal.

54. :

The method of claim 53, wherein the data bit zero of the baseband data signal is represented by a plurality of logic low levels in the encoded data signal.

55. :

The method of claim 48, wherein the RFID tag is affixed to an object, and the identification code is associated with the object.

56. :

The method of claim 55, further comprising affixing the RFID tag to the object and associating the identification code with the object.

57. :

The method of claim 48, wherein transmitting the command comprises the use of spread spectrum communication.

58. :

The method of claim 57, further comprising band limiting the encoded data signal before using the encoded data signal to modulate the carrier wave.

59. :

The method of claim 48, wherein the RFID reader communicates to the RFID tag a selected one of a plurality of data rates, and the reply is received at the selected one of the plurality of data rates.

60. :

A method of communicating between a radio frequency identification (RFID) reader and at least one RFID tag, the method comprising;

providing an RFID tag affixed to an object, the RFID tag comprising an antenna and a single monolithic integrated circuit coupled to the antenna and configured to modulate an impedance of the antenna to enable backscatter communication with the RFID reader, the integrated circuit having stored therein an identification code associated with the object;

providing the RFID reader coupled to a host computer, the RFID reader configured to transmit a continuous wave after transmitting a command, the continuous wave to enable backscatter communication with the RFID tag;

encoding a baseband data signal, including performing selective inversion responsive to a predetermined data value, to generate an encoded data signal wherein a data bit zero of the baseband data signal is represented by both logic high and logic low levels in the encoded data signal; and

modulating a carrier wave using the encoded data signal to communicate between the RFID reader and the RFID tag, the modulating using a modulation format selected from a group consisting of amplitude modulation, phase modulation, and amplitude and phase modulation.

61. :

The method of claim 60, wherein the host computer associates the identification code with the object.

62. :

The method of claim 61, further comprising affixing the RFID tag to the object and associating the identification code with the object.

63. :

The method of claim 60, further comprising providing power to the RFID tag from a battery.

64. :

The method of claim 60, wherein the impedance of the antenna is configured to be modulated by modulating a reflectivity of the antenna.

65. :

The method of claim 60, wherein the data bit zero of the baseband data signal is represented by a plurality of logic high levels in the encoded data signal.

66. :

The method of claim 65, wherein the data bit zero of the baseband data signal is represented by a plurality of logic high levels and a plurality of logic low levels in the encoded data signal.

67. :

The method of claim 66, further comprising the use of spread spectrum to communicate between the RFID reader and the RFID tag.

68. :

The method of claim 60, wherein the command indicates a selected data rate of a plurality of data rates, and the RFID tag communicates with the RFID reader at the selected data rate in response to the command.

69. :

The method of claim 60, wherein the carrier wave is generated by the RFID reader.

70. :

A radio frequency identification (RFID) reader configured to communicate with a plurality of RFID tags, the RFID reader comprising;

a data path configured to provide a baseband data signal comprising a command;

a circuit to generate an encoded data signal wherein a data bit zero of the baseband data signal is represented by at least one logic high level and at least one logic low level in the encoded data signal and a data bit one of the baseband data signal is represented by at least one logic high level and at least one logic low level in the encoded data signal;

a signal generator configured to generate a carrier signal to be modulated during transmission of commands to the RFID tags and to be provided as a continuous wave during reception of replies from the RFID tags in accordance with backscatter communication;

a modulator configured to both amplitude modulate and phase modulate the carrier signal using the encoded data signal;

a transmitter to transmit the amplitude and phase modulated carrier signal; and

a receiver to receive a reply to the command from at least one RFID tag.

71. :

The RFID reader of claim 70, further comprising a host computer to receive the reply, the reply including an identification code, the host computer configured to associate the identification code with an object to which the RFID tag is affixed.

72. :

The RFID reader of claim 71, further comprising a filter to band limit the encoded data signal.

73. :

The RFID reader of claim 70, wherein the circuit is further configured to generate the encoded data signal wherein the data bit one of the baseband data signal is represented by a plurality of logic high levels in the encoded data signal.

74. :

The RFID reader of claim 70, further comprising a spread spectrum processing unit configured the implement spread spectrum transmission from the RFID reader.

75. :

The RFID reader of claim 74, further comprising a filter to band limit the encoded data signal.

76. :

The RFID reader of claim 75, further comprising a host computer configured to receive the reply, the reply including an identification code, the host computer further configured to associate the identification code with an object to which the RFID tag is affixed.

77. :

The RFID reader of claim 75, wherein the command indicates a selected one of a plurality of data rates, and the receiver is configured to receive the reply at the selected one of the plurality of data rates.

78. :

A radio frequency identification (RFID) system, comprising;

an RFID reader comprising a transmitter configured to transmit a carrier signal that is modulated during a first period of time and that is unmodulated during a second period of time, and a receiver configured to receive the carrier signal modulated during the second period of time by one or more RFID tags in accordance with backscatter communication;

an object to be tracked;

an RFID tag affixed to the object, the RFID tag comprising a receiver to receive a command from the RFID reader during the first period of time, and a transmitter to modulate the carrier signal during the second period of time to communicate a reply to the RFID reader in accordance with backscatter communication;

a computer coupled to the RFID reader to associate the object with an identification code stored in the RFID tag; and

a circuit configured to receive a baseband data signal and to generate an encoded data signal therefrom, including performing selective inversion responsive to a predetermined data value, the circuitry further configured to modulate the carrier wave by the encoded data signal using a modulation format selected from a group consisting of amplitude modulation, phase modulation, and amplitude and phase modulation.

79. :

The RFID system of claim 78, wherein the RFID tag further comprises a battery to provide power to the RFID tag.

80. :

The RFID system of claim 78, wherein the RFID tag further comprises an antenna, and the transmitter is configured to modulate the carrier signal by modulating a reflectivity of the antenna.

81. :

The RFID system of claim 78, wherein the circuit is configured to encode a data bit zero of the baseband data signal into at least one logic high level and at least one logic low level in the encoded data signal.

82. :

The RFID system of claim 81, wherein the circuit is configured to encode a data bit zero of the baseband data signal into a plurality of logic high levels and a plurality of logic low levels in the encoded data signal.

83. :

The RFID system of claim 78, wherein the RFID reader further comprises a spread spectrum processor to implement spread spectrum communication between the RFID reader and the RFID tag.

84. :

The RFID system of claim 78, wherein the command indicates a selected data rate of a plurality of data rates, and the RFID tag is configured to communicate the reply at the selected data rate.