BACKSCATTERING TYPE RFID COMMUNICATION SYSTEM

• US 20110181397A1
• Filed: 04/05/2011
• Published: 07/28/2011
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: IDRO Company Limited
• Original Assignee: IDRO Company Limited
• Inventors: PARK, Jungsung, OH, Kwangjin, KANG, Yanggi
• Granted Patent: US 9,479,229 B2
• Time in Patent Office: Days
• US Class Current: 340/10.2
• 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 19/0728 the arrangement being an optical or sound-based communication interface
• CPC Class Codes: G06K 7/0004 Hybrid readers
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A backscattering type radio frequency identification (RFID) communication system, and more particularly, a backscattering type RFID communication system in which an RFID tag transmits a signal back to an RF reader by using energy of a carrier wave transmitted by the RFID reader. Provided is a backscattering type radio frequency identification (RFID) communication system RFID communications are performed efficiently without an error while interference between RFID readers does not occur even under an overcrowded reader environment. Interference of RF signals between the RFID readers does not occur, and RFID communications can be efficiently performed even under the overcrowded reader environment. Transmitting and receiving time steps of the RFID readers do not need to be synchronized with one another so that compatibility of the RFID readers can be improved.

Claims

1. A backscattering type radio frequency identification (RFID) communication system comprising:

a plurality of RFID readers, each of the plurality of RFID readers comprising;

a reader controller generating a query signal to be transmitted to an RFID tag;

a visible ray transmitting unit transmitting the query signal transmitted by the reader controller in a form of visible rays;

a reader transmitter transmitting a carrier wave in a form of RF by selecting one from among a plurality of frequency channels; and

a reader receiver receiving a response signal in a form of RF transmitted from the RFID tag and transmitting the response signal to the reader controller; and

a plurality of RFID tags, each of the plurality of RFID tags comprising;

a visible ray receiving unit receiving the query signal transmitted by the visible ray transmitting unit of the RFID reader and converting the query signal into an electrical signal;

a tag receiver receiving the carrier wave transmitted by the reader transmitter of the RFID reader;

a tag controller processing a command of the query signal received by the visible ray receiving unit and generating a response signal with respect to the query signal; and

a tag transmitter transmitting the response signal transmitted by the tag controller in a form of an RF carrier signal with respect to the carrier wave by using energy of the carrier wave received by the tag receiver.

2. The backscattering type RFID communication system of claim 1, wherein the reader transmitter of the RFID reader changes a frequency of the carrier wave into one frequency channel randomly selected from among the plurality of frequency channels at regular intervals.

3. The backscattering type RFID communication system of claim 1, wherein, after checking whether the same frequency channel as a frequency channel of the carrier wave to be transmitted is used by another RFID reader, the RFID reader transmits the carrier wave upon the frequency channel when the frequency channel is not used by another RFID reader.

4. The backscattering type RFID communication system of claim 2, wherein, after checking whether the same frequency channel as a frequency channel of the carrier wave to be transmitted is used by another RFID reader, the RFID reader transmits the carrier wave upon the frequency channel when the frequency channel is not used by another RFID reader.

5. The backscattering type RFID communication system of claim 3, wherein the tag transmitter of the RFID tag transmits the response signal at a frequency of the same frequency channel as the carrier wave received to a manner to be resonant to the carrier wave, a frequency of a frequency channel adjacent to the frequency channel of the carrier wave or a frequency of a boundary between the frequency channel of the carrier wave and a frequency channel adjacent to the frequency channel of the carrier wave.

6. The backscattering type RFID communication system of claim 4, wherein the tag transmitter of the RFID tag transmits the response signal at a frequency of the same frequency channel as the carrier wave received to a manner to be resonant to the carrier wave, a frequency of a frequency channel adjacent to the frequency channel of the carrier wave or a frequency of a boundary between the frequency channel of the carrier wave and a frequency channel adjacent to the frequency channel of the carrier wave.

7. The backscattering type RFID communication system of claim 1, wherein the visible ray transmitting unit of the RFID reader comprises an encoder encoding the query signal transmitted by the reader controller, a modulator modulating the encoded query signal, and an emission unit converting the modulated query signal into a visible ray signal.

8. The backscattering type RFID communication system of claim 2, wherein the visible ray transmitting unit of the RFID reader comprises an encoder encoding the query signal transmitted by the reader controller, a modulator modulating the encoded query signal, and an emission unit converting the modulated query signal into a visible ray signal.

9. The backscattering type RFID communication system of claim 7, wherein the modulator of the visible ray transmitting unit modulates a signal by using amplitude shift keying (ASK).

10. The backscattering type RFID communication system of claim 8, wherein the modulator of the visible ray transmitting unit modulates a signal by using ASK.

11. The backscattering type RFID communication system of claim 9, wherein the modulator of the visible ray transmitting unit modulates a signal by using on/off keying (OOK) with a modulation index of 100%.

12. The backscattering type RFID communication system of claim 1, wherein the visible ray receiving unit of the RFID tag comprises a light receiving unit receiving the query signal in a form of visible rays and converting the query signal into an electrical signal, a demodulator demodulating the query signal transmitted from the light receiving unit, and a decoder decoding the demodulated query signal and transmitting the query signal to the tag controller.

13. The backscattering type RFID communication system of claim 2, wherein the visible ray receiving unit of the RFID tag comprises a light receiving unit receiving the query signal in a form of visible rays and converting the query signal into an electrical signal, a demodulator demodulating the query signal transmitted from the light receiving unit, and a decoder decoding the demodulated query signal and transmitting the query signal to the tag controller.

14. The backscattering type RFID communication system of claim 1, wherein the tag transmitter of the RFID tag comprises an encoder encoding the response signal transmitted by the tag controller and a backscattering unit converting the response signal transmitted from the encoder into a carrier signal that is resonant to the carrier wave.

15. The backscattering type RFID communication system of claim 2, wherein the tag transmitter of the RFID tag comprises an encoder encoding the response signal transmitted by the tag controller and a backscattering unit converting the response signal transmitted from the encoder into a carrier signal that is resonant to the carrier wave.

16. The backscattering type RFID communication system of claim 1, wherein the reader receiver of the RFID reader generates a signal having a reverse phase to a phase of the carrier wave and having the same magnitude as a magnitude of the carrier wave flowing through the reader receiver and adds the signal to the reader receiver, thereby removing the carrier wave flowing through the reader receiver.

17. The backscattering type RFID communication system of claim 2, wherein the reader receiver of the RFID reader generates a signal having a reverse phase to a phase of the carrier wave and the same magnitude as a magnitude of the carrier wave flowing through the reader receiver and adds the signal to the reader receiver, thereby removing the carrier wave flowing through the reader receiver.