Radio-frequency identification tag communication device

• US 20070001811A1
• Filed: 09/11/2006
• Published: 01/04/2007
• Est. Priority Date: 03/19/2004
• Status: Active Grant

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Kiyohara, Yuji
• Granted Patent: US 7,573,389 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854

Abstract

A radio-frequency identification tag communication device including a BFA weight-value setting portion operable to control a directivity of a transmitter antenna, and an adaptive processing portion operable to implement an adaptive control of a weight to be given to a received signal received by each of a plurality of antenna elements, on the basis of a reply signal transmitted from a radio-frequency identification tag, so that the directivity of the transmitter antenna is changed to a direction in which the frequency identification tag in question is expected to exist, and the weight to be given to each received signal is subjected to the adaptive control, whereby the sensitivity of communication of the communication device with the radio-frequency identification tag is improved.

Claims

1. A radio-frequency identification tag communication device for radio communication with a radio-frequency identification tag, by transmitting a transmission signal from a transmitter antenna toward the radio-frequency identification tag, and receiving a reply signal transmitted from the radio-frequency identification tag in response to the transmission signal, through a receiver antenna comprising a plurality of antenna elements, said radio-frequency identification tag communication device comprising:

a directivity control portion configured to control a directivity of said transmitter antenna; and

an adaptive weight control portion configured to implement an adaptive control of a weight to be given to a received signal received by each of said plurality of antenna elements of said receiver antenna, on the basis of said reply signal transmitted from said radio-frequency identification tag.

2. The radio-frequency identification tag communication device according to claim 1, wherein said transmitter antenna comprises a plurality of antenna elements, and said directivity control portion is configured to control at least one of a phase and an amplitude of the transmission signal to be transmitted from each of said plurality of antenna elements, for thereby controlling the directivity of the transmitter antenna.

3. The radio-frequency identification tag communication device according to claim 2, wherein the transmission signals to be respectively transmitted from said plurality of antenna elements of said transmitter antenna and the received signals to be respectively received by said plurality of antenna elements if said receiver antenna have a same frequency, said adaptive weight control portion controls the weight to be given to said received signals such that the weight to be given to said received signals is different from a weight to be given to said transmission signals.

4. The radio-frequency identification tag communication device according to claim 1, wherein said adaptive weight control portion is operable to set an initial value of the weight to be given to each received signal, on the basis of the directivity of the transmitter antenna set by said directivity control portion.

5. The radio-frequency identification tag communication device according to claim 1, wherein said directivity control portion is configured to set again the directivity of said transmission antenna, on the basis of a value of the weight into which the weight has been converged by said adaptive control of the weight to be given to the received signal by said adaptive processing portion.

6. The radio-frequency identification tag communication device according to claim 1, wherein said transmitter antenna and said receiver antenna commonly use a plurality of antenna elements.

7. The radio-frequency identification tag communication device according to claim 2, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion operable to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion operable to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

8. The radio-frequency identification tag communication device according to claim 1, wherein said directivity control portion is configured to control the weight to be given to said transmission signal, so as to maximize a density of transmission power in a direction determined by the directivity of said transmitter antenna.

9. The radio-frequency identification tag communication device according to claim 2, wherein said adaptive weight control portion is configured to implement the adaptive control of the weight to be given to each of the received signals received by said plurality of antenna elements, so as to maximize a signal-to-noise ratio of a composite signal which is synthesized by combining together said received signals to which the weight has been given.

10. The radio-frequency identification tag communication device according to claim 1, wherein said transmitter antenna comprises a plurality of antenna elements, and said transmitter antenna and said receiver antenna have at least one common antenna element, said directivity control portion being configured to give a weight to the transmission signal to be transmitted from each of said at least one common antenna element, while said adaptive weight control portion being configured to give the weight to the received signal received by each of said at least one common antenna element.

11. The radio-frequency identification tag communication device according to claim 3, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

12. The radio-frequency identification tag communication device according to claim 4, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

13. The radio-frequency identification tag communication device according to claim 5, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

14. The radio-frequency identification tag communication device according to claim 6, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

15. The radio-frequency identification tag communication device according to claim 2, wherein said directivity control portion is configured to set again the directivity of said transmission antenna, on the basis of a value of the weight into which the weight has been converged by said adaptive control of the weight to be given to the received signal by said adaptive processing portion.

16. The radio-frequency identification tag communication device according to claim 15, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

17. The radio-frequency identification tag communication device according to claim 3, wherein said directivity control portion is configured to set again the directivity of said transmission antenna, on the basis of a value of the weight into which the weight has been converged by said adaptive control of the weight to be given to the received signal by said adaptive processing portion.

18. The radio-frequency identification tag communication device according to claim 17, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.

19. The radio-frequency identification tag communication device according to claim 4, wherein said directivity control portion is configured to set again the directivity of said transmission antenna, on the basis of a value of the weight into which the weight has been converged by said adaptive control of the weight to be given to the received signal by said adaptive processing portion.

20. The radio-frequency identification tag communication device according to claim 19, said directivity control portion comprises one of a phased-array control portion and a beam forming control portion configured to control the weight to be given to each of the transmission signals to be transmitted from said plurality of antenna elements, on the basis of the directivity of the transmitter antenna, and said adaptive weight control portion comprises an adaptive-array control portion configured to implement the adaptive control of the weight to be given to each of the received signals to be received by said plurality of antenna elements.