METHODS AND SYSTEMS OF RECEIVING DATA PAYLOAD OF RFID TAGS

• US 20080297324A1
• Filed: 05/30/2007
• Published: 12/04/2008
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Tuttle, John R.
• Granted Patent: US 8,134,452 B2
• Time in Patent Office: Days
• US Class Current: 340/10.33
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

Methods and systems of receiving data payload of RFID tags. At least some of the illustrative embodiments are methods comprising selecting (by each of a plurality of radio frequency identification (RFID) tags) a time window within which to transmit (the selecting to create respective time windows), sending a start signal from a RFID reader to the plurality of RFID tags (the start signal indicative of the start of a first time window), and transmitting a signal by each of the plurality of RFID tags in the respective time windows.

Claims

1. A method comprising:

selecting, by each of a plurality of radio frequency identification (RFID) tags, a time window within which to transmit, the selecting to create respective time windows;

sending a start signal from a RFID reader to the plurality of RFID tags, the start signal indicative of the start of a first time window; and

transmitting a signal, by each of the plurality of RFID tags, in the respective time windows.

2. The method according to claim 1 wherein selecting further comprises, for each of the plurality of RFID tags:

generating a random number; and

selecting a time window based on the random number.

3. The method according to claim 2 wherein selecting the time window further comprises selecting the time window directly indicated by the random number.

4. The method according to claim 1 further comprising receiving, by the RFID reader, signals in at least some of the time windows.

5. The method according to claim 4 further comprising:

determining whether two RFID tags transmitted within a time window; and

if so

repeating the selecting and transmitting.

6. The method according to claim 5 wherein determining further comprises receiving a signal in a time window where error detection bits indicate invalid data.

7. The method according to claim 5 wherein determining further comprises receiving a signal in a time window where error correction bits received are insufficient to correct data errors.

8. The method according to claim 5 wherein repeating further comprises transmitting at a center frequency different than a center frequency used in the initial transmitting.

9. The method according to claim 1 further comprising broadcasting a wake signal from the RFID reader to the RFID tags.

10. The method according to claim 7 further comprising, prior to selecting the time windows, sending a signal by the RFID reader to set an interaction mode.

11. The method according to claim 7 wherein broadcasting further comprises broadcasting a continuous wave electromagnetic signal to provide power to the plurality of RFID tags.

12. The method according to claim 7 further comprising sending a start signal as a cycling of the continuous wave electromagnetic signal.

13. The method according to claim 1 further comprising sending a width signal by a RFID reader to the RFID tags, the width signal indicative of a time width of each time window.

14. A radio frequency identification (RFID) tag comprising:

a tag antenna; and

a RFID circuit coupled to the tag antenna;

wherein the RFID circuit is configured to transmit a message to a RFID reader, transmission of the message beginning at a particular time selected at random by the RFID tag.

15. The RFID tag according to claim 14 wherein the RFID circuit, responsive to a signal from the RFID reader, is configured to generate a random number, the random number used to identify the particular time.

16. The RFID tag according to claim 14 further comprising:

a memory within the RFID circuit, the memory storing data;

wherein the RFID circuit is configured to transmit at least a portion of the data at the particular time selected.

17. The RFID tag according to claim 16 wherein the memory stores one or more selected from the group consisting of:

an electronic product code;

user defined data; and

a kill password.

18. The RFID tag according to claim 14 wherein the RFID circuit is configured to receive signal from the RFID reader indicative of the start time, and the particular time selected is a particular time after receipt of the signal.

19. The RFID tag according to claim 14 wherein operating power for the RFID circuit is derived from one or more selected from the group consisting of:

an internal battery; and

power received from the RFID reader circuit.

20. The RFID tag according to claim 14 wherein the RFID tag transmits by backscattering electromagnetic signals.

21. A system comprising:

a reading antenna; and

a radio frequency identification (RFID) reader coupled to the reading antenna;

wherein the RFID reader is configured to simultaneously activate a plurality of RFID tags, and the RFID reader is configured to receive responses from all of the plurality of RFID tags without further communication to the plurality of RFID tags from the RFID reader.

22. The system according to claim 21 wherein when the RFID reader activates the plurality of RFID tags, the RFID reader sends a timing signal indicative of a first period of time in which a response can be received.

23. The system according to claim 21 wherein when the RFID reader activates the plurality of RFID tags, the RFID reader broadcasts a continuous wave electromagnetic signal.

24. The system according to claim 21 wherein when the RFID reader receives responses, the RFID reader broadcasts a continuous wave electromagnetic signal and receives responses as backscattered electromagnetic waves.

25. The system according to claim 21 wherein the system is further configured to determine whether any of the responses from the plurality of RFID tags are ambiguous, and if any of the responses are ambiguous, the RFID reader is further configured to again simultaneously activate the plurality of RFID tags.

26. The system according to claim 25 further comprising an electronic system coupled to the RFID reader, and wherein the electronic system determines whether unambiguous responses were received from each of the plurality of RFID tags.

27. The system according to claim 25 wherein when the system determines whether unambiguous responses were received, the system determines whether cyclic redundancy check (CRC) codes for each response match data of each response.