Adjusting communication parameters while inventorying RFID tags

• US 7,830,262 B1
• Filed: 06/04/2008
• Issued: 11/09/2010
• Est. Priority Date: 04/25/2006
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Thomas, Michael H., Esterberg, Aanand, Ord, David, Diorio, Christopher J., Sundstrom, Kurt E.
• Primary Examiner(s): Mehmood; Jennifer
• Application Number:
  US12/133,180
• Time in Patent Office: 888 Days
• Field of Search: 3405721-5729, 340 101- 106, 375/350
• US Class Current: 340/572.4
• 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 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator

Abstract

RFID reader systems, readers, components, software and methods are provided for inventorying RFID tags. In some embodiments, a population of RFID tags begins being inventoried using a first set of communication parameters, and then continues using a second set of communication parameters. This way, some RFID tags can be inventoried faster, without missing tags that require a longer time to read.

Claims

1. An operational processing block for a Radio Frequency Identification (RFID) reader to inventory a population of RFID tags, comprising:

a component for;

causing to be established a first set of values for communication parameters;

causing to be transmitted first inventorying commands for inventorying the RFID tags, and receiving, responsive to the first inventorying commands, first replies that are backscattered from a first subgroup of RFID tags in the population, at least one of the first inventorying commands and the first replies using communication parameters having the first set of values;

then causing to be established a second set of values for the communication parameters, different from the first set of values; and

causing to be transmitted second inventorying commands that are suitable for continuing inventorying those of the RFID tags in the population that are not in the first subgroup, but not suitable for continuing inventorying at least one of those that is in the first subgroup, and receiving, responsive to the second inventorying commands, second replies that are backscattered from a second subgroup of RFID tags in the population that does not include the first subgroup, at least one of the second inventorying commands and the second replies using communication parameters having the second set of values,

in which at least one tag of the first subgroup and at least one tag of the second subgroup are powered from both the first and the second inventorying commands, and remain continuously powered during a transition between the first and the second inventorying commands.

2. The operational processing block of claim 1, in which

a receive filter is adjusted to accommodate receiving the first replies, and

the receive filter is then further adjusted to accommodate the second replies.

3. The operational processing block of claim 2, in which

the first replies are received at a first tag data rate, and

the second replies are received at a second tag data rate different from the first tag data rate.

4. The operational processing block of claim 2, in which the first commands are transmitted at frequencies consistent with those called for in the Gen2 Spec v.1.1.0,

one of the communication parameters is a Miller Parameter MP defined consistently with how the Miller parameter M is defined in the Gen2 Spec v.1.1.0. the Miller Parameter MP capable of assuming a value of one of 1, 2, 4, and 8, and

the receive filter includes a Band Pass Filter that optimizes a Signal to Noise Ratio best for the value of MP=4, less well for a value of MP=8, even less or not at all for a value of MP=2 or MP=1.

5. The operational processing block of claim 1, in which

one of the communication parameters is a Miller parameter MP defined consistently with how the Miller parameter is defined in the Gen2 Spec v.1.1.0.

6. The operational processing block of claim 1, in which

one of the communication parameters is a backscatter link frequency.

7. The operational processing block of claim 1, in which

the first inventorying commands are encoded in terms of at least a first symbol for data-0 and a second symbol for data-1, and

one of the communication parameters indicates a duration of one of the first and the second symbols.

8. The operational processing block of claim 1, in which the first inventorying commands are encoded in terms of at least a first symbol for data-0 and a second symbol for data-1, and

one of the communication parameters indicates a ratio of durations between the first and the second symbols.

9. The operational processing block of claim 1, in which

one of the communication parameters includes a pilot tone indication that indicates whether or not one of the first replies should be preceded by a pilot tone, and

one of the first replies is preceded by a pilot tone in accordance with the pilot tone indication.

10. The operational processing block of claim 1, in which

the first inventorying commands and the second inventorying commands are transmitted in a single frequency channel, without having transmitted in another frequency channel between when the first inventorying commands and the second inventorying commands were caused to be transmitted.

11. The operational processing block of claim 1, in which

the first inventorying commands and the second inventorying commands are transmitted out of a single antenna, without having transmitted out of another antenna between when the first inventorying commands and the second inventorying commands were caused to be transmitted.

12. The operational processing block of claim 1, in which

the second inventorying commands are suitable for continuing inventorying those of the RFID tags in the population that are not in the first subgroup, but not suitable for continuing inventorying any of those that are in the first subgroup.

13. The operational processing block of claim 1, in which

the first inventorying commands are transmitted while a current session has been established, the current session selected from one of available sessions S0, S1, S2 and S3 defined consistently with respective sessions SO, S 1, S2 and S3 that are defined in the Gen2 Spec v. 1.1.0

a certain RFID tag of the first subgroup includes a current session flag for the current session, the session flag being capable of one of two states A and B which is flipped responsive to the certain RFID tag becoming inventoried by the first inventorying commands, and

the second inventorying commands are caused to be transmitted without having caused the current session flag to be further changed during a subsequent transition between the first inventorying commands and the second inventorying commands being transmitted.

14. The operational processing block of claim 1, in which the component is further

for:

then causing to be established a third set of values for the communication parameters, different from the first and from the second sets of values; and

causing to be transmitted third inventorying commands that are suitable for continuing inventorying those RFID tags in the population that are not in the first subgroup or in the second subgroup, but not at least one of those that is in the first subgroup and at least one of those that is in the second subgroup, the third inventorying commands using communication parameters having the third set of values,

in which at least one tag of the first subgroup, at least one tag of the second subgroup, and at least one tag of the third subgroup are powered from the first and the second and the third inventorying commands, and remain continuously powered during transitions between the first and the second inventorying commands, and the second and the third inventorying commands.

15. The operational processing block of claim 14, in which the component is further for:

receiving, responsive to the third inventorying commands, third replies that are backscattered from a third subgroup of RFID tags in the population that does not include the first subgroup or the second subgroup, the third replies using communication parameters having the third set of values.

16. The operational processing block of claim 14, in which

no replies are received from the RFID tags responsive to the third inventorying commands.

17. The operational processing block of claim 16, in which the component is further for:

then causing to be established a fourth set of values for the communication parameters, different from the first and from the second and from the third sets of values; and

causing to be transmitted fourth inventorying commands that are suitable for continuing inventorying those RFID tags in the population that are not in the first subgroup or in the second subgroup, but not those that are in the first subgroup or in the second subgroup, the fourth inventorying commands using communication parameters having the fourth set of values.

18. The operational processing block of claim 1, in which the component is further for:

causing to be established a zeroth set of values for the communication parameters, different from the first and from the second sets of values; and

causing to be transmitted zeroth inventorying commands that are suitable for inventorying the RFID tags in the population, and receiving, responsive to the zeroth inventorying commands, zeroth replies that are backscattered from some RFID tags in the population, at least one of the zeroth inventorying commands and the zeroth replies using communication parameters having the zeroth set of values,

in which the zeroth replies are received prior to causing the first inventorying commands to be transmitted, and

the zeroth replies are received from some tags in the population that belong in the first subgroup and some in the second subgroup.

19. The operational processing block of claim 1, in which

a Received Signal Strength Indicator (RSSI) is determined from the first replies, and

the second set of values is caused to be established if the RSSI is below a threshold.

20. The operational processing block of claim 1, in which

an error metric is determined about the first replies, and

the second set of values is caused to be established if the error metric exceeds a threshold.

21. The operational processing block of claim 1, in which

the second set of values is caused to be established before detecting that there are no more first replies.

22. The operational processing block of claim 1, in which

the second set of values is caused to be established responsive to detecting no more first replies.

23. The operational processing block of claim 1, in which

an estimate is obtained for the number of the RFID tags in the population, and

the second set of values is caused to be established responsive to determining that the first replies do not account for the entire population estimate.

24. The operational processing block of claim 23, in which

the estimate is obtained as an input from a user.

25. A method for a Radio Frequency Identification (RFID) reader system component to cause inventorying of a population of RFID tags, comprising:

causing to be established a first set of values for communication parameters;

causing to be transmitted first inventorying commands for inventorying the RFID tags, and receiving, responsive to the first inventorying commands, first replies that are backscattered from a first subgroup of RFID tags in the population, at least one of the first inventorying commands and the first replies using communication parameters having

the first set of values;

then causing to be established a second set of values for the communication parameters, different from the first set of values; and

causing to be transmitted second inventorying commands that are suitable for continuing inventorying those of the RFID tags in the population that are not in the first subgroup, but not suitable for continuing inventorying at least one of those that is in the first subgroup, and receiving, responsive to the second inventorying commands, second replies that are backscattered from a second subgroup of RFID tags in the population that does not include the first subgroup, at least one of the second inventorying commands and the second replies using communication parameters having the second set of values,

in which at least one tag of the first subgroup and at least one tag of the second subgroup are powered from both the first and the second inventorying commands, and remain continuously powered during a transition between the first and the second inventorying commands.

26. The method of claim 25, further comprising:

then causing to be established a third set of values for the communication parameters, different from the first and from the second sets of values; and

causing to be transmitted third inventorying commands that are suitable for continuing inventorying those RFID tags in the population that are not in the first subgroup or in the second subgroup, but not at least one of those that is in the first subgroup and at least one of those that is in the second subgroup, the third inventorying commands using communication parameters having the third set of values,

in which at least one tag of the first subgroup, at least one tag of the second subgroup, and at least one tag of the third subgroup are powered from the first and the second and the third inventorying commands, and remain continuously powered during transitions between the first and the second inventorying commands, and the second and the third inventorying commands.

27. The method of claim 26, further comprising:

receiving, responsive to the third inventorying commands, third replies that are backscattered from a third subgroup of RFID tags in the population that does not include the first subgroup or the second subgroup, the third replies using communication parameters having the third set of values.

28. The method of claim 26, in which

no replies are received from the RFID tags responsive to the third inventorying commands.

29. The method of claim 28, further comprising:

then causing to be established a fourth set of values for the communication parameters, different from the first and from the second and from the third sets of values; and

causing to be transmitted fourth inventorying commands that are suitable for continuing inventorying those RFID tags in the population that are not in the first subgroup or in the second subgroup, but not those that are in the first subgroup or in the second subgroup, the fourth inventorying commands using communication parameters having the fourth set of values.

30. The method of claim 25, further comprising:

causing to be established a zeroth set of values for the communication parameters, different from the first and from the second sets of values; and

causing to be transmitted zeroth inventorying commands that are suitable for inventorying the RFID tags in the population, and receiving, responsive to the zeroth inventorying commands, zeroth replies that are backscattered from some RFID tags in the population, at least one of the zeroth inventorying commands and the zeroth replies using communication parameters having the zeroth set of values,

in which the zeroth replies are received prior to causing the first inventorying commands to be transmitted, and

the zeroth replies are received from some tags in the population that belong in the first subgroup and some in the second subgroup.

31. An article comprising:

a storage medium, the storage medium having instructions stored thereon, in which when the instructions are executed by at least a Radio Frequency Identification (RFID) reader system component, the instructions result in actions for inventorying a population of RFID tags, the actions comprising;

causing to be established a first set of values for communication parameters;

causing to be transmitted first inventorying commands for inventorying the RFID tags, and receiving, responsive to the first inventorying commands, first replies that are backscattered from a first subgroup of RFID tags in the population, at least one of the first inventorying commands and the first replies using communication parameters having the first set of values;

then causing to be established a second set of values for the communication parameters, different from the first set of values; and

causing to be transmitted second inventorying commands that are suitable for continuing inventorying those of the RFID tags in the population that are not in the first subgroup, but not suitable for continuing inventorying at least one of those that is in the first subgroup, and receiving, responsive to the second inventorying commands, second replies that are backscattered from a second subgroup of RFID tags in the population that does not include the first subgroup, at least one of the second inventorying commands and the second replies using communication parameters having the second set of values,

in which at least one tag of the first subgroup and at least one tag of the second subgroup are powered from both the first and the second inventorying commands, and remain continuously powered during a transition between the first and the second inventorying commands.