Communication methods, systems, apparatus, and devices involving RF tag registration

• US 20060071757A1
• Filed: 09/24/2004
• Published: 04/06/2006
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Skorpik, James R., Burghard, Brion J.
• Granted Patent: US 7,362,212 B2
• Time in Patent Office: Days
• US Class Current: 340/10.200
• 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 7/10029 the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot

Abstract

One technique of the present invention includes a number of Radio Frequency (RF) tags that each have a different identifier. Information is broadcast to the tags from an RF tag interrogator. This information corresponds to a maximum quantity of tag response time slots that are available. This maximum quantity may be less than the total number of tags. The tags each select one of the time slots as a function of the information and a random number provided by each respective tag. The different identifiers are transmitted to the interrogator from at least a subset of the RF tags.

Claims

1. A method, comprising:

operating several RF tags within communication range of an RF tag interrogator, the RF tags each including a respective random number generator and a respective one of a several different identification numbers, the different identification numbers each being unique relative to one another, one or more of the RF tags reporting the respective one of the different identification numbers to the interrogator, said reporting including the one or more of the RF tags each;

seeding the respective random number generator with the respective one of the different identification numbers to generate a first random number;

determining a first time period to transmit the respective one of the different identification numbers as a function of the first random number;

failing to properly transmit the respective one of the different identification numbers to the interrogator during the first time period;

seeding the respective random number generator with the first random number to provide a second random number; and

determining a second time period to transmit the respective one of the unique identification numbers to the interrogator as a function of the second random number.

2. The method of claim 1, which includes seeding the respective random number generator with the second random number after said determining the second time period.

3. The method of claim 1, wherein the respective random number generator is a pseudorandom type.

4. The method of claim 1, wherein:

the several RF tags belong to an RF tag set;

the several different identification numbers belong to a corresponding identifier set, the identifier set being effective to unique identify up to a maximum tag quantity in the RF tag set; and

the several RF tags number at least one order of magnitude less than the maximum tag quantity.

5. The method of claim 1, wherein:

said seeding the respective random number generator with the respective one of the different identification numbers is performed in response to a first tag identifier report command broadcast by the interrogator; and

said seeding the respective random number generator with the first random number is performed in response to a second tag identifier report command broadcast by the interrogator.

6. The method of claim 5, which includes broadcasting a suppression command with the interrogator to suppress response of a subset of the RF tags to the second tag identifier report command.

7. The method of claim 1, wherein:

said failing to properly transmit includes the one or more of the RF tags each detecting the transmission of one or more other of the RF tags before transmitting the respective one of the different identification numbers during the first time; and

performing said seeding the respective random number generator with the first random number in response to said detecting.

8. The method of claim 1, wherein said failing to properly transmit is caused by a communication collision during the first time.

9. A method, comprising:

operating several RF tags each including a respective one of a number of different identifiers, the different identifiers being unique relative to one another;

broadcasting a first tag report command with an RF tag interrogator to a subset of the RF tags, the subset being the RF tags within communication range of the interrogator, the first command including a parameter corresponding to a maximum quantity of tag response time slots, the subset including more of the RF tags than the maximum quantity of tag response time slots;

for each of the RF tags belonging to the subset, selecting a respective one of the time slots as a function of the parameter and a random number, and transmitting the respective one of the different identifiers to the interrogator during the respective one of the time slots;

with the interrogator, detecting a communication collision for at least one of the time slots and storing one or more of the different identifiers transmitted from the subset during one or more other of the time slots; and

in response to a second tag report command sent by the interrogator;

transmitting the respective one of the different identifiers to the interrogator from at least one of the RF tags that caused the collision.

10. The method of claim 9, wherein the function of the parameter and the random number further is performed in accordance with a maximum quantity of uniquely identifiable tags, the subset of the RF tags numbering at least one order of magnitude less than the maximum quantity.

11. The method of claim 9, which includes for each of the RF tags belonging to the subset:

generating the random number with a random number generator, and

seeding the random number generator with the respective one of the different identifiers in response to the first command.

12. The method of claim 9, which includes broadcasting a suppression command with the interrogator after said broadcasting the first command and before said transmitting, the suppression command suppressing a response to the second command by each of the RF tags belonging to the subset for which the interrogator stored the respective one of the different identifiers.

13. The method of claim 9, which includes:

performing the first command and the second command with the interrogator at a first location;

moving the interrogator from the first location to a second location;

interrogating a different subset of the RF tags with the interrogator after said moving, the different subset including a number of RF tags not included in the subset; and

transmitting the respective one of the different identifiers for each of the number of RF tags of the different subset in response to said interrogating.

14. A method, comprising:

operating a number of RF tags included in an RF tag set, the RF tags each including a respective one of a set of different identifiers, the set of different identifiers being effective to unique identify up to a maximum tag quantity in the RF tag set;

broadcasting information to a subset of the RF tags from an RF tag interrogator, the subset being the RF tags within communication range of the interrogator, the information corresponding to a maximum quantity of tag response time slots, the maximum quantity being at least one order of magnitude less than the maximum tag quantity;

each respective one of the RF tags of the subset selecting one of the time slots as a function of the information and a random number provided with the respective one of the RF tags of the subset; and

transmitting the different identifiers from at least a portion of the subset to the interrogator.

15. The method of claim 14, wherein the maximum quantity is at least two orders of magnitude less than the maximum tag quantity, and the subset of the RF tags numbers at least two orders of magnitude less than the maximum tag quantity, and further comprising:

performing said broadcasting of the information with the interrogator at a first location;

moving the interrogator from the first location to a second location;

interrogating a different subset of the RF tags with the interrogator after said moving, the different subset including one or more of the RF tags not included in the subset; and

transmitting the respective one of the different identifiers for each of the one or more of the RF tags of the different subset in response to said interrogating.

16. The method of claim 14, which includes in response to said broadcasting each respective tag of the subset generating the random number with a respective random number generator seeded with the respective one of the different identifiers.

17. The method of claim 16, wherein said broadcasting the information is in the form of a command, and further comprising:

broadcasting a further command with the interrogator to suppress a response to a subsequent command by a plurality of the RF tags of the subset for which the interrogator has stored the respective one of the different identifiers; and

broadcasting the subsequent command with the interrogator to which one or more of the RF tags of the subset responds, the plurality of the RF tags of the subset being nonresponsive to the subsequent command based on the further command.

18. The method of claim 17, which includes for each of the one or more of the RF tags of the subset, generating another random number by seeding the respective random number generator with the random number in response to the subsequent command.

19. A method, comprising:

operating several RF tags each including a respective one of a number of different identifiers, the different identifiers being unique relative to one another;

broadcasting a command with an RF tag interrogator to a subset of the RF tags, the subset being the RF tags within communication range of the interrogator, the subset numbering two or more of the RF tags and numbering more of the RF tags than a maximum quantity of time slots available for each of the RF tags to respond to the command;

responding to the command with each of the RF tags of the subset;

providing a respective random number, selecting one of the time slots as a function of the respective random number, and transmitting the respective one of the different identifiers during the one of the time slots;

with the interrogator, detecting a communication collision causing failure of proper transmission to the interrogator of the respective one of the different identifiers by one or more of the RF tags of the subset and storing the respective one of the different identifiers transmitted without the failure for each of a remainder of the RF tags in the subset;

broadcasting a further command to the subset;

responding to the further command with the one or more of the RF tags causing the failure; and

suppressing response to the further command by the remainder of the RF tags of the subset.

20. The method of claim 19, which includes:

performing said broadcasting of the command and said broadcasting of the further command, with the interrogator at a first location;

moving the interrogator from the first location to a second location;

interrogating a different subset of the RF tags with the interrogator after said moving, the different subset including at least one of the RF tags not included in the subset; and

transmitting the respective one of the different identifiers for each of the at least one of the RF tags of the different subset in response to said interrogating the different subset.

21. The method of claim 19, which includes in response to the command, generating the respective random number with a random number generator seeded with the respective one of the different identifiers for each of the RF tags of the subset.

22. The method of claim 19, wherein said suppressing includes broadcasting a suppression command between after said broadcasting the command and before said broadcasting the further command, further comprising:

broadcasting a further suppression command to suppress a response to at least one subsequent command by the RF tags of the subset having the respective one of the different identifiers previously stored with the interrogator; and

broadcasting the subsequent command to the subset, the RF tags of the subset suppressed by the further suppression command being nonresponsive to the subsequent command and the remainder of the RF tags of the subset being responsive to the subsequent command.

23. A method, comprising:

operating a number of RF tags included in an RF tag set, the RF tags each including a respective one of a corresponding set of different identifiers, the set of different identifiers being effective to uniquely identify a maximum tag quantity;

performing an interrogation with an RF tag interrogator to determine the respective one of the different identifiers of each of the RF tags in a subset, the subset numbering two or more of the RF tags and being at least one order of magnitude less than the maximum tag quantity; and

respective tags of the subset each responding by;

waiting for a time period determined as a function of at least a randomly determined number and a delay period;

detecting if a different tag of the subset is transmitting;

if transmission by the different tag of the subset is detected, waiting for another time period determined as a function of at least another random number and the delay period; and

transmitting the respective one of the unique identifiers to the interrogator if the transmission by the different tag is not detected.

24. The method of claim 23, which includes the respective tags each:

seeding a random number generator with a respective one of the different identifiers to generate the randomly determined number; and

seeding the random number generator with the randomly determined number to generate the second randomly determined number.

25. The method of claim 23, which includes performing multiple interrogation passes in a first period of time to register all of the RF tags of the subset.

26. The method of claim 25, wherein the delay period is shorter than a longer delay period, the longer delay period corresponding to that required to register all of the RF tags of the subset in a single pass in a second period of time, the second period of time being longer than the first period of time.

27. The method of claim 23, which includes empirically adjusting the delay period to reduce time for the interrogator to verify that the respective one of the different identifiers for all the RF tags of the subset have been reported.

28. A system, comprising:

RF communication circuitry operable to perform RF tag interrogation; and

an RF interrogator processing subsystem coupled to the interrogation circuitry, the processing subsystem being operable to register a number of the deployed RF tags within a communication range of the circuitry by performing a registration procedure, the registration procedure including a tag report command to cause each of the deployed RF tags to transmit a unique identifier, the tag identifier report command including one parameter corresponding to a maximum quantity of RF tag response time slots available and a different parameter corresponding to randomization of a selection of a respective one of the time slots by each of the deployed RF tags, the registration procedure being effective to determine if a communication collision occurred during one or more of the time slots in response to the tag report command and to store the unique identifier transmitted by each of the deployed RF tags during one or more other of the time slots for which the communication collision did not occur, the registration procedure further being effective to suppress response of one or more of the tags to a subsequent tag report command, the unique identifier for the one or more of the tags being previously recognized by the processing subsystem in response to the tag report command.

29. The system of claim 28, wherein the RF circuitry and the RF interrogator processing subsystem are included in a portable RF interrogator.

30. The system of claim 29, further comprising the deployed RF tags, the deployed RF tags each including:

RF tag communication circuitry; and

an RF tag processing subsystem coupled to the RF tag communication circuitry, the RF tag processing subsystem including a random number generator, the RF tag processing subsystem being effective to select the respective one of the time slots as a function of the parameter included in the information and a random number generated with the random number generator being seeded in accordance with the different parameter.

31. The system of claim 29, further comprising the deployed RF tags, the deployed RF tags each including:

RF tag communication circuitry; and

an RF tag processing subsystem coupled to the RF tag communication circuitry, the RF tag processing subsystem including a random number generator and a unique identification number, the RF tag processing subsystem including in accordance with logic responsive to a first tag report command transmitted by the interrogator to;

seed the random number generator with a first seed corresponding to the unique identifier to generate a first random number, determine a first time as a function of the first random number to attempt transmission of the unique identification number, seed the random number generator with a second seed corresponding to the first random number to generate a second random number if the transmission at the first time fails to be properly performed, and determine a second time as a function of the second random number to attempt the transmission of the unique identification number.

32. The system of claim 31, wherein the random number generator is of a pseudorandom type.

33. A system, comprising:

RF tag communication circuitry; and

an RF tag processing subsystem coupled to the circuitry, the processing subsystem including a random number generator, the random number generator being seeded in accordance with information received through the RF tag communication circuitry, the processing subsystem being effective to determine a time slot to transmit an identifier through the RF tag communication circuitry, the identifier being unique relative to a quantity of deployed RF tags, the time slot being determined as a function of a random number provided by the random number generator and a parameter included in the information, the parameter corresponding to a maximum quantity of transmission time slots to respond to a broadcast command, the maximum quantity of the time slots being less than the quantity of deployed RF tags by at least one order of magnitude.

34. The system of claim 33, wherein the random number generator is of a pseudorandom type.

35. The system of claim 33, wherein the RF tag communication circuitry and the RF tag processing subsystem are included in an active RF tag, the RF tag including one or more sensors.

36. The system of claim 35, further comprising several other RF tags deployed in a region.

37. The system of claim 35, further comprising means for interrogating the active RF tag, the interrogating means including means for broadcasting the information including the parameter.

38. The system of claim 33, wherein the logic is further responsive to a different parameter included in the information, the different parameter including a first form to seed the random number generator with the identifier and a second form to seed the random number generator with the random number previously generated with the random number generator.

39. A system, comprising:

RF tag communication circuitry; and

an RF tag processing subsystem coupled to the circuitry, the processing subsystem including a random number generator and a unique identification number, the processing subsystem including logic responsive to one or more commands received through the communication circuitry to;

seed the random number generator with a first seed corresponding to the unique identification number to generate a first random number, determine a first time as a function of the first random number to attempt transmission of the unique identification number, seed the random number generator with a second seed corresponding to the first random number to generate a second random number if the transmission at the first time fails to be properly performed, and determine a second time as a function of the second random number to attempt the transmission of the unique identification number.

40. The system of claim 39, wherein the random number generator is of a pseudorandom type.

41. The system of claim 39, wherein the RF tag communication circuitry and the RF tag processing subsystem are included in an active RF tag.

42. The system of claim 41, further comprising several other RF tags deployed in a region.

43. The system of claim 41, further comprising an RF interrogator operable to broadcast a first tag report command belonging to the one or more commands, the first tag report command including information to direct the RF tag to seed the random number generator with the first seed, to determine if the transmission at the first time fails to be properly performed, and to broadcast a second tag report command to direct the RF tag to seed the random number generator with the second seed if failure of the transmission at the first time is detected.

44. The system of claim 43, wherein the logic is further responsive to a suppression command from the interrogator to suppress response to the second tag report command if the transmission at the first time of the unique identification number to be interrogator is successfully completed.

45. The system of claim 41, wherein the logic is operable to detect transmission by a different active RF tag before performing the transmission at the first time and to determine the transmission at the first time fails to be properly performed if the different active RF tag is detected.

46. The system of claim 41, further comprising means for broadcasting the one or more commands with at least one of the commands including a parameter, the parameter corresponding to a maximum number of available RF tag response time slots, the logic being operable to randomly select one of the time slots, the one of the time slots corresponding to the first time.