Multiple Item Radio Frequency Tag Identification Protocol

• US 20070176751A1
• Filed: 01/02/2007
• Published: 08/02/2007
• Est. Priority Date: 09/09/1994
• Status: Abandoned Application

• Current Assignee: Arvind Krishna, Christian Cesar, Dilip Kandlur, Harley Heinrich, Kenneth Goldman, Kevin Mcauliffe, Sharon Greene, Shun Chan, Thomas Colino
• Original Assignee: Arvind Krishna, Christian Cesar, Dilip Kandlur, Harley Heinrich, Kenneth Goldman, Kevin Mcauliffe, Sharon Greene, Shun Chan, Thomas Colino
• Inventors: Heinrich, Harley, Cesar, Christian, Goldman, Kenneth, Greene, Sharon, Krishna, Arvind, Kandlur, Dilip, Colino, Thomas, Chan, Shun, McAuliffe, Kevin
• Application Number:
  US11/619,131
• Publication Number:
  US 20070176751A1
• Time in Patent Office: Days
• US Class Current: 340/10.320
• CPC Class Codes: G05B 19/0421 Multiprocessor system
• CPC Class Codes: G05B 2219/2231 Master slave
• CPC Class Codes: G05B 2219/25277 Tristate
• 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 7/10108 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: G07C 9/28 the pass enabling tracking or indicating presence
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 2201/20 Binding and programming of remote control devices

Abstract

An exemplary embodiment uses a novel adaptation of a tree splitting algorithm applied to Radio Frequency (RE) tagging technology to identify many tags in the RF field of a base station. The embodiment uses the tree splitting algorithm to identify a single tag in a field of a plurality of radio frequency tags. Once the single tag is identified, the identified tag is placed in a Data_Exchange state where the base station can access data from the tag memory by using information that identifies the tag.

Claims

1. A radio frequency tag for communicating with a base station, comprising:

a. an antenna and tag radio frequency circuit for sending and receiving radio frequency signals to and from the base station;

b. a tag memory for storing tag data;

c. a tag logic circuit connected to the tag radio frequency circuit and the tag memory, the tag logic circuit having a tag state register that indicates the tag is in a state that is one of the states including READY, ID, and Data Exchange, the tag logic further having a state counter and a random number generator; and

d. a tag algorithm, run by the tag logic, that places the tag in the READY state by setting the state register to READY when the tag is powered and places the tag in the ID state by setting the state register to ID when the base station sends the tag an identification command.

2. A tag, as in claim 1, where the identification command is a Group_select command and the tag transmits a command response back to the base station while the tag is in the ID state.

3. A tag, as in claim 2, where the command response is tag identification information.

4. A tag, as in claim 3, where the tag receives a Fail command from the base station that causes the tag algorithm to increase a state counter value in the state counter if:

a. the state counter has a value not equal to a predetermined value, or

b. the state counter has a value equal to the predetermined value and the random number generator has a given value, whereby the tag stops transmitting the tag identification information while the state counter value is not equal to the predetermined value and the tag algorithm causes the random number generator to generate a new random value.

5. A tag, as in claim 4, where the tag receives a Resend command from the base station that causes the tag algorithm to decrease the state counter value.

6. A tag, as in claim 5, where the tag starts sending the tag identification information when the state counter value is equal to a predetermined value.

7. A tag, as in claim 6, where the base station sends the tag a READ command and the tag algorithm places the tag in the Data_Exchange state whereby the base station can sent one or more application commands to the tag by identifying the tag with the identification information sent to the base station.

8. A tag, as in claim 5, where the Fail command causes the tag algorithm to decrease the state counter value and the Resend command causes the tag algorithm to increase the state counter value.

9. A tag, as in claim 5, where the predetermined value is zero and the given value is zero.

10. A tag, as in claim 5, where the algorithm increases the state counter by one for each Fail command sent and decrements the state counter by one for each Resend command sent whereby the base station has read the identification information from every tag in a field of tags when the number of Fail and Resend commands are equal.

11. A tag, as in claim 5, where the tag algorithm resets the value in the state counter to the predetermined value when the tag receives a Group_select command from the base station.

12. A tag, as in claim 1, where the tag algorithm places the tag in the READY state by resetting the state register to READY when the tag receives a Group_unselect command from the base station.

13. A tag, as in claim 1, where the tag is placed in the Data_Exchange state by setting the state register to Data_Exchange when the tag receives a READ command from the base station whereby the tag sends back an acknowledgement.

14. A system for reading information from a plurality of radio frequency tags that are in the field of a radio frequency signal sent by a reader, comprising:

i. a tag, further comprising;

a. an antenna and tag radio frequency circuit for sending and receiving radio frequency signals to and from the reader;

b. a tag memory for storing tag data;

c. a tag logic circuit connected to the tag radio frequency circuit and the tag memory, the tag logic circuit having a tag state register that indicates the tag is in a state that is one of the states including READY, ID, and Data Exchange, the tag logic further having a state counter and a random number generator; and

d. a tag algorithm, run by the tag logic;

ii. a reader that is able to transmit information commands to the field of tags, the information commands including a Group_select, a Fail, and a Resend command,

a. the Group_select command causing the tag algorithm to place one or more selected tags in the ID state by causing each selected tag algorithm to set its respective state register to ID and reset its respective state counter to a predetermined value,

b. the Fail command being generated by the reader when more than one tag sends tag identification information to the reader simultaneously, the Fail command causing the algorithm of each selected tag to increment its respective state counter if;

1) the state counter has a value not equal to a predetermined value, or

2) the state counter has a value equal to the predetermined value and the random number generator has a given value,

c. the Resend command sent by the reader when tag identification information is sent back to the reader in response to a READ command by a single tag in the field, the Resend command causing the state counter of all the tags in the field to decrement,

whereby the reader can identify an individual tag in the field of tags, and cause the identified tag to go into a Data_Exchange state where the reader can access information from the tag memory.

15. A method, for reading a radio frequency identification tag in a radio frequency field of a plurality of tags comprising the steps of:

a. sending a group_select command from a reader that places one or more selected tags in the field in a ID state;

b. sending identification information from all the selected tags to the reader;

c. sending a fail command from the reader if more than one tag sends identification information simultaneously;

d. increasing a state counter value in the state counter of one or more selected tags if;

1) the state counter has a value not equal to a predetermined value, or

2) the state counter has a value equal to the predetermined value and the random number generator has a given value, the tag stopping transmission of the tag identification information while the state counter value is not equal to the predetermined value and the tag algorithm causing the random number generator to generate a new random value;

e. sending identification information a next time from all the selected tags to the reader, the selected tags having a state counter value equal to the predetermined value;

f. repeating steps c-e until a sole tag is sending identification information to the reader;

g. issuing a READ command to the sole tag using the identification information of the sole tag; and

h. placing the sole tag in a Data_exchange state where the reader can access data from the sole tag memory by using application commands.

16. A system for selecting a subset of slaves that satisfy a selection criterion, and causing the selected subset of slaves to participate in an identification and isolation process whereby slaves of the selected subset are successively identified and isolated from further participation in such identification and isolation process, said system comprising:

(a) a master unit for communicating a command containing a selection criterion to a plurality of slaves;

(b) each slave of said plurality of slaves being in one of three or more different possible conditions during the identification and isolation process;

(c) a memory in said each slave containing at least one information value for use in evaluation of a selection criterion;

(d) a receiving unit in said each slave for receiving the command containing the selection criterion from the master unit; and

(e) a processing unit in said each slave that processes the command containing the selection criterion from the master unit;

(f) the processing units of the slaves having a mode of operation such that a subgroup of slaves that have an information value that satisfies the selection criterion are moved from a first condition to a second condition for participation in an identification and isolation process; and

(g) the processing units of the subgroup of slaves in the second condition having a mode of operation whereby individual slaves of said subgroup can progress to a third condition during the identification and isolation process, with slaves that have progressed to the third condition, and have been identified, being isolated from further participation in the identification and isolation process that continues so as to identify and isolate other of the slaves in the second condition.

17. A method for selecting a subset of slaves that satisfy at least one selection criterion during a selection process, and then identifying slaves of the selected subset, and causing identified slaves of the selected subset of slaves to be isolated from further participation in the identification process, said method comprising;

(a) storing at least one information value in each of a plurality of slaves for use in evaluating at least one selection criterion;

(b) representing at least one selection criterion in at least one selection criterion command;

(c) communhicating the at least one selection criterion command to the plurality of slaves;

(d) processing the at least one selection criterion command at each of said plurality of slave and deeming certain of the slaves based on storage of the at least one information value to be selected as a result of the selection process;

(e) carrying out an identification process with respect to the certain slaves deemed selected as a result of the selection process; and

(f) causing slaves that are identified during the identification process of clause (e) to be isolated trom responding farther in the course of the identification process of clause (e).