Method, system, and apparatus for communications in a RFID system

• US 20060061474A1
• Filed: 11/14/2005
• Published: 03/23/2006
• Est. Priority Date: 02/12/2001
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Powell, Kevin J., Shanks, Wayne E., Arneson, Michael R.
• Granted Patent: US 7,928,843 B2
• Time in Patent Office: Days
• US Class Current: 340/572.100
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• CPC Class Codes: G06K 19/0713 the arrangement including a power charge pump
• 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 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• 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 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags
• CPC Class Codes: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A method, system, and apparatus for interrogating a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader. The reader and tags engage in communication according to communications algorithms, where data symbols are exchanged between the reader and tags. Furthermore, a reader implicitly controls the operating state of every tag in the tag population by transmitting a single data symbol. Bit patterns may be collected from the tags by the reader, using a variety of interrogation techniques. In a general interrogation, the reader exchanges symbols with the tag population to interrogate the entire tag population. In a specific interrogation, a reader exchanges symbols with the tag population to target a particular tag identification number. Tags may also be placed in a superposition state by the reader, where they respond whenever a received data symbol matches the next bit of their identification number.

Claims

1. A method in a radio frequency identification (RFID) tag for communicating with a reader, wherein the tag stores sensor data as a first bit pattern and stores an identification number as a second bit pattern, comprising:

(a) receiving a symbol from the reader;

(b) transmitting a first bit of the first bit pattern to the reader;

(c) receiving a next symbol from the reader; and

(d) if the previously transmitted bit is not a last bit of the first bit pattern, transmitting a next bit of the first bit pattern and returning to step (c).

2. The method of claim 1, further comprising:

(e) transmitting a first bit of the second bit pattern to the reader;

(f) receiving a next symbol from the reader; and

(g) if the previously transmitted bit is not a last bit of the second bit pattern, transmitting a next bit of the second bit pattern and returning to step (f).

3. The method of claim 1, further comprising:

(e) receiving information from a sensor; and

(f) storing the information as the second bit pattern.

4. A method in a radio frequency identification (RFID) reader for interrogating a plurality of tags, wherein each tag stores sensor data as a bit pattern, comprising:

(a) communicating with the plurality of tags according to an interrogation protocol, including;

(i) transmitting interrogation signals to the plurality of tags, and

(ii) receiving sensor data bit patterns stored in the tags in response to the interrogation signal; and

(b) storing the received sensor data bit patterns.

5. The method of claim 4, wherein said communicating further comprises:

performing a binary traversal of the population of tags.

6. The method of claim 5, wherein the sensor data bit patterns are received from the tags in an order based on the sensor data bit patterns.

7. A method of reading radio frequency identification (RFID) tags associated with items classified according to a packaging hierarchy, wherein the RFID tags each have a identification number assigned thereto, comprising:

(a) determining a level in the packaging hierarchy for items desired to be read;

(b) determining a bit pattern corresponding to the determined level; and

(c) communicating with tags according to an interrogation protocol to read tags that have the determined bit pattern in a predetermined location of their identification number.

8. The method of claim 7, wherein step (c) comprises:

transitioning tags that do not have the determined bit pattern in the predetermined location of their identification number to a mute state.

9. The method of claim 7, wherein the interrogation protocol is a binary protocol.

10. The method of claim 7, wherein the level can be an item level, a box level, a carton level, a tote level, or a pallet level.

11. A radio frequency identification (RFID) tag, comprising:

a substrate;

an antenna on the substrate;

a storage that stores an identification number, wherein the identification number includes a bit pattern portion that identifies a level in a packaging hierarchy for the tag;

a receiver coupled to the antenna, wherein the receiver receives a carrier signal received by the antenna from a reader; and

a modulator coupled to the antenna, wherein the modulator is configured to backscatter modulate the carrier signal with bits of the bit pattern portion.

12. The tag of claim 11, wherein the bit pattern represents an item level, a box level, a carton level, a tote level, or a pallet level in the packaging hierarchy.

13. A method in a radio frequency identification (RFID) tag for communicating with a reader, comprising:

storing an identification number, wherein the identification number includes a bit pattern portion that identifies a level in a packaging hierarchy for the tag;

receiving a carrier signal from a reader; and

backscatter modulating the carrier signal with bits of the bit pattern portion to identify the level in the packaging hierarchy for the tag to the reader.

14. The method of claim 13, wherein said backscatter modulating comprises:

identifying the level in the packaging hierarchy for the tag as an item level, a box level, a carton level, a tote level, or a pallet level.

15. A method in a reader for communicating information with radio frequency identification (RFID) tags, comprising:

(a) receiving a bit pattern representing information;

(b) transmitting the bit pattern to at least one tag, wherein the tag stores the information; and

(c) communicating with the at least one tag according to an interrogation protocol to read the bit pattern from the tag.

16. The method of claim 15, wherein the interrogation protocol is a binary protocol.

17. A radio frequency identification (RFID) tag, comprising:

a substrate;

an antenna on the substrate, wherein the antenna receives a modulated carrier signal from a reader;

a receiver coupled to the antenna, wherein the receiver recovers a bit pattern from the received modulated carrier signal; and

a storage that stores an identification number for the tag and stores the bit pattern.

18. The tag of claim 17, further comprising:

a modulator coupled to the antenna, wherein the modulator is configured to backscatter modulate a carrier signal transmitted by a second reader with bits of the stored bit pattern to provide the bit pattern to the second reader.

19. The tag of claim 18, wherein the first reader and the second reader are the same reader.

20. The tag of claim 17, wherein the storage includes volatile storage that stores the bit pattern.

21. The tag of claim 17, wherein the storage includes non-volatile storage that stores the bit pattern.

22. A method in a radio frequency identification (RFID) tag for communicating with a reader, comprising:

storing an identification number;

receiving a modulated carrier signal from a reader;

recovering a bit pattern from the received modulated carrier signal; and

storing the bit pattern.

23. The tag of claim 22, further comprising:

backscatter modulating a carrier signal transmitted by a second reader with bits of the stored bit pattern to provide the bit pattern to the second reader.