APPARATUS AND METHOD FOR TRANSMITTING TAG AND READER RECEIVING APPARATUS

• US 20150009014A1
• Filed: 04/15/2014
• Published: 01/08/2015
• Est. Priority Date: 07/02/2013
• Status: Abandoned Application

• Current Assignee: Electronics and Telecommunications Research Institute, Foundation For Research & Business, Seoul National University of Science & Technology
• Original Assignee: Electronics and Telecommunications Research Institute, Foundation For Research & Business, Seoul National University of Science & Technology
• Inventors: MO, Sang Hyun, BAE, Ji-Hoon, JUNG, Jae-young, YANG, Hoe-Sung, PARK, Chan-Won, PYO, Cheol Sig, PARK, Hyung Chul
• Application Number:
  US14/253,379
• Publication Number:
  US 20150009014A1
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G06K 7/10059 transponder driven
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications

Abstract

A tag transmitting apparatus of a passive RFID (radio frequency identification) system generates a pilot tone, a preamble, and an SFD (start frame delimiter) and transmits the pilot, the preamble, and the SFD, using one of a plurality of square waves.

Claims

1. A method of transmitting tag data in a passive RFID (radio frequency identification) system, the method comprising:

generating a pilot tone, a preamble, and an SFD (start frame delimiter);

generating a plurality of square waves; and

transmitting the pilot tone, the preamble, and the SFD using one of the square waves.

2. The method of claim 1, further comprising:

converting tag data inputted in series into a plurality of parallel data; and

transmitting the parallel data using the square waves.

3. The method of claim 2, wherein the square waves are orthogonal to each other.

4. The method of claim 1, wherein the preamble includes a 4 bit signal.

5. The method of claim 4, wherein the 4 bit signal is −

1, 1, 1, and −

1.

6. The method of claim 1, wherein the SFD includes a 4 bit signal.

7. The method of claim 6, wherein the 4 bit signal is −

1, 1, 1, and −

1.

8. The method of claim 1, wherein the pilot tone includes a bit signal composed of zeros, and is used for estimating transmission speed of a transmitted signal from the tag.

9. An apparatus for transmitting a tag which transmits tag data in a passive RFID (radio frequency identification) system, the apparatus comprising:

signal generators that each generate a pilot tone, a preamble, an SFD (start frame delimiter), and tag data;

a plurality of square wave generators that generate a plurality of square waves to use as subcarriers;

a plurality of calculators that calculate and output input data and a plurality of square waves, respectively;

a plurality of load modulators that perform load modulation on the signals of the square waves and then transmit the signals, respectively; and

a de-multiplexer that outputs the pilot tone, the preamble, and the SFD to one of the square wave generators, converts the tag data into a plurality of parallel data, and then outputs the parallel data to the square wave generators.

10. The apparatus of claim 9, wherein the square waves are orthogonal to each other.

11. The apparatus of claim 9, wherein the preamble and the SFD include a 4 bit signal.

12. The apparatus of claim 10, wherein the 4 bit signal is −

1, 1, 1, and −

1.

13. The apparatus of claim 9, wherein the pilot tone includes a bit signal composed of zeros, and is used for estimating transmission speed of the tag.

14. The apparatus of claim 10, wherein a selected one of the square wave generators generates a square wave having a lowest frequency in the square waves.

15. A reader receiving apparatus that receives a tag signal from a tag of a passive RFID (radio frequency identification) system, the apparatus comprising:

a frequency estimator that estimates transmission speed offset of a received signal, using cross-correlation between a received pilot tone signal and a reference pilot tone signal, and compensates for the transmission speed offset;

a preamble detector that detects whether there is a tag signal, using auto-correlation of a received preamble signal; and

an SFD (start frame delimiter) detector that detects a start point of time of a payload from the tag signal, using cross-correlation between a received SFD signal and a reference SFD signal.

16. The apparatus of claim 15, wherein the pilot tone signal is a signal obtained by performing an XOR (exclusive OR) operation on continuous 0 bit signals and a square wave.

17. The apparatus of claim 16, wherein the frequency estimator multiplies an I-signal of the pilot tone signal by one cycle signal of the square wave, multiplies a Q-signal of the pilot tone signal by a cycle signal delayed by ¼

of the square wave, estimates frequency offset from the sum of the signals, and estimates transmission speed offset from the frequency offset.

18. The apparatus of claim 15, wherein:

the preamble signal is obtained by performing an XOR operation on a 4 bit signal of −

1, 1, 1, −

1 and a square wave.

19. The apparatus of claim 15, wherein the SFD signal is a signal obtained by performing an XOR operation on a 4 bit signal of −

1, 1, 1, −

1 and a square wave.