Location virtualization in an RFID system

• US 7,667,575 B2
• Filed: 07/29/2005
• Issued: 02/23/2010
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Quake Global, Inc.
• Original Assignee: Reva Systems Corp. (Quake Global, Inc.)
• Inventors: Spreadborough, Peter, Fischer, Jeffrey H., Husak, David J., Krishna, Pattabhiraman
• Primary Examiner(s): Zimmerman; Brian A
• Assistant Examiner(s): Nguyen; Nam V
• Application Number:
  US11/194,144
• Publication Number:
  US 20060170565A1
• Time in Patent Office: 1,670 Days
• Field of Search: 340/10.2, 340/10.31, 340/572.1, 340/825.69, 370/314, 708/250, 708/255, 707/1, 707/3
• US Class Current: 340/10.2
• CPC Class Codes: G01S 5/02525 Gathering the radio frequency fingerprints
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G06K 17/0029 the arrangement being specially adapted for wireless interrogation of grouped or bundled articles tagged with wireless record carriers
• 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 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

A system and method of determining locations of one or more RFID tags within an RFID environment. The system includes a plurality of RFID readers, each operative to transmit and receive RF signals for scanning a tag disposed within an RF coverage region associated with the reader, and for receiving tag data in response to the scanning of the tag. A plurality of sub-locations is determined within the environment, each corresponding to at least a portion of at least one of a plurality of RF coverage regions associated with the readers. The sub-locations are mapped to a plurality of predefined locations within the environment. A reader scans a tag, and receives tag scan data from the tag in response to the scanning of the tag. The tag scan data includes a tag identifier associated with the scanned tag. The tag scan data is mapped to the sub-locations based on the RF coverage region associated with the reader. The location of the scanned tag is then determined with reference to the predefined locations within the environment, based on the tag identifier included in the tag scan data, the mapping of the tag scan data to the sub-locations, and the mapping of the sub-locations to the predefined locations.

Claims

1. A computer implemented method of operating a radio frequency identification (RFID) system within an environment, said RFID system including a plurality of RF interrogators for transmitting RF interrogation signals to at least one RFID tag, and a plurality of RF receivers for receiving RF signals containing RFID tag data from at least one RFID tag, each of said plurality of RF interrogators and said plurality of RF receivers having an RF coverage zone associated therewith, each RF coverage zone corresponding to a region within said environment, said method comprising:

in a first determining step, determining, by a processor, a plurality of sub-regions within said environment, each sub-region corresponding to at least a portion of at least one RF coverage zone associated with at least one RF receiver or at least one RF interrogator;

in a first mapping step, mapping, by said processor, said plurality of sub-regions to a plurality of predefined regions within said environment;

storing, by said processor in a data storage, information defining the mapping of said plurality of sub-regions to said plurality of predefined regions within said environment;

in a receiving step, receiving, at one of said plurality of RF receivers, RFID tag data from one of said at least one RFID tag;

in a second mapping step, mapping, by said processor, the received RFID tag data to at least one of said plurality of sub-regions based at least upon the RF coverage zone associated with the respective RF receiver that received said RFID tag data from the respective RFID tag, or the RF coverage zone associated with the respective RF interrogator that transmitted the RF interrogation signal to the respective RFID tag;

in a second determining step, determining, by said processor using the mapping of said RFID tag data to said at least one of said plurality of sub-regions and the stored information defining the mapping of said plurality of sub-regions to said plurality of predefined regions, an RFID tag location of the respective RFID tag with reference to said plurality of predefined regions within said environment;

repeating said receiving step, said second mapping step, and said second determining step;

in a third determining step, determining a plurality of RFID tag locations of said one of said at least one RFID tag within the environment;

in a fourth determining step, determining a first plurality of likelihood estimates of said one of said at least one RFID tag being located at the plurality of RFID tag locations, respectively;

in a fifth determining step, determining a first maximum of the first plurality of likelihood estimates;

in a sixth determining step, determining a single RFID tag location of said one of said at least one RFID tag based upon said first maximum likelihood determination;

in an seventh determining step, determining a second plurality of likelihood estimates of said one of said at least one RFID tag being located at the plurality of sub-regions, respectively; and

in a eighth determining step, determining a second maximum of the second plurality of likelihood estimates, and determining the single RFID tag location of said one of said at least one RFID tag based at least in part upon said second maximum likelihood determination,

wherein said seventh determining step further includes;

determining at least one region of overlap of said plurality of RF coverage zones associated with said plurality of RF receivers or RF interrogators, respectively;

identifying at least one set of RF receivers or RF interrogators having RF coverage zones corresponding to said at least one region of overlap of said plurality of RF coverage zones;

identifying at least one of the plurality of sub-regions within said environment corresponding to said at least one region of overlap of said plurality of RF coverage zones;

determining the second plurality of likelihood estimates of said one of said at least one RFID tag being located at the plurality of sub-regions, respectively, based upon said at least one identified set of RF receivers or RF interrogators and said at least one identified sub-region; and

determining a probability band P disposed around each RF receiver or RF interrogator, said probability band P being expressed as

P(<

T,R,t>

|T at x),

wherein “

T”

is an identifier of said one of said at least one RFID tag, “

R”

is an identifier of the respective RF receiver or RF interrogator, “

t”

corresponds to a timestamp indicative of a most recent time point of RFID tag data reception or RFID tag interrogation, “

x”

represents a respective one of the plurality of sub-regions, and said probability band P expressed as “

P(<

p>

|T at x)”

corresponds to the likelihood of said RFID tag having the first identifier T being observed when said RFID tag T is located at said sub-region x.

2. The method of claim 1 wherein said first mapping step comprises mapping the plurality of sub-regions within said environment to at least one physical location within said environment.

3. The method of claim 1 wherein said first mapping step includes mapping the plurality of sub-regions to a selected one of a plurality of sets of predefined regions within said environment, said selected set of predefined regions being associated with at least one software application, and wherein said method further includes the steps of generating RFID tag location data corresponding to said at least one RFID tag location determined in said second determining step, providing said RFID tag location data to at least one computer running said at least one software application, receiving said RFID tag location data as input by said at least one software application, and processing said RFID tag location data by said at least one software application with reference to said selected set of predefined regions associated therewith.

4. The method of claim 3 wherein said RFID tag location data includes one or more of an identifier of said at least one RFID tag location, an identifier of said one of said at least one RFID tag, an identifier of said one of said at least one RF receiver, and a timestamp indicative of a most recent time point when said RFID tag data was received at said one of said at least one RF receiver.

5. The method of claim 1 including the step of determining at least one likelihood estimate of said one of said at least one RFID tag being located at said at least one RFID tag location.

6. The method of claim 1 including the step of determining at least one likelihood estimate of said one of said at least one RFID tag being located at said at least one of the plurality of sub-regions within said environment.

7. The method of claim 1 including a third determining step, said third determining step including determining at least one likelihood estimate of said RFID tag data from said one of said at least one RFID tag being received at the respective RF receiver, or at least one likelihood estimate of the RF interrogation signal transmitted by the respective RF interrogator being received at said one of said at least one RFID tag.

8. The method of claim 1 including the step of generating an ordered sequence of the first plurality of likelihood estimates, and including a ninth determining step, said ninth determining step including determining the plurality of RFID tag locations of said one of said at least one RFID tag based upon said ordered sequence of likelihood estimates.

9. The method of claim 1 wherein said eighth determining step includes determining the second maximum of the second plurality of likelihood estimates by comparing each of the second plurality of likelihood estimates to a predetermined threshold value.

10. The method of claim 1 wherein said seventh determining step includes expressing said probability band P as

P(<

T,R,t>

|T at x)≧

PROB_THRESH,

wherein “

PROB_THRESH”

is a specified threshold value.

11. The method of claim 1 wherein said seventh determining step includes determining said probability band P disposed around each RF receiver or RF interrogator, wherein said probability band P corresponds to the RF coverage zone of the respective RF receiver or RF interrogator.

12. The method of claim 1 wherein the receiving step includes receiving, at said one of said at least one RF receiver, RFID tag data from a plurality of RFID tags, wherein said method includes the step of generating information <

T,R,t>

for each of said plurality of RFID tags, wherein said method includes a tenth determining step, said tenth determining step including determining whether identical information <

T,R,t>

is generated for at least two of the plurality of RFID tags, wherein said method includes the step of, in the event identical information <

T,R,t>

is generated for at least two of the plurality of RFID tags, designating RFID tag data from at least one of said at least two RFID tags as redundant RFID tag data, and wherein said method includes a first filtering step, said first filtering step including filtering out said redundant RFID tag data before performing said second mapping step.

13. The method of claim 12 wherein said first filtering step is performed during at least one specified time interval.

14. The method of claim 13 including a second filtering step, said second filtering step including filtering out old RFID tag data having at least one corresponding timestamp t indicating that said old RFID tag data was received at the respective RF receiver before a predetermined time point.

15. The method of claim 14 wherein said second filtering step includes filtering out old RFID tag data having at least one corresponding timestamp t indicating that said old RFID tag data was received at the respective RF receiver before a predetermined time point based upon a multiple of said specified time interval for filtering out the redundant RFID tag data.

16. The method of claim 1 wherein said first determining step includes determining said plurality of sub-regions within said environment, each sub-region corresponding to at least a portion of at least one RF coverage zone associated with at least one RF receiver or at least one RF interrogator, and wherein each RF receiver or RF interrogator corresponds to a respective logical RF receiver or RF interrogator having an associated operating profile.

17. The method of claim 16 wherein said operating profile includes information selected from the group consisting of a sensitivity level, an operating mode, an RFID air protocol, and a direction of at least one antenna associated with the RF receiver or RF interrogator corresponding to the respective logical RF receiver or RF interrogator.

18. The method of claim 16 wherein said first determining step includes determining the plurality of sub-regions within said environment, wherein each sub-region corresponds to at least a portion of at least one of a plurality of RF coverage zones, and wherein the RF coverage zone associated with the RF receiver or RF interrogator corresponding to the respective logical RF receiver or RF interrogator is based at least in part upon the operating profile of the respective logical RF receiver or RF interrogator.

19. The method of claim 1 wherein said first mapping step includes mapping the plurality of sub-regions to the plurality of predefined regions, wherein each of the plurality of predefined regions within said environment has at least one associated boundary, and wherein at least one of the sub-regions mapped in the first mapping step extends across at least one boundary associated with at least one of the plurality of predefined regions.

20. The method of claim 19 including a third determining step, said third determining step including, in the event the received RFID tag data is mapped in said first mapping step to said at least one sub-region extending across said at least one boundary associated with said at least one of the plurality of predefined regions, determining said at least one RFID tag location of said one of said at least one RFID tag as being within the predefined region having said associated boundary.

21. The method of claim 19 including a third determining step, said third determining step including, in the event the received RFID tag data is mapped in said first mapping step to said at least one sub-region extending across said at least one boundary associated with said at least one of the plurality of predefined regions, determining said at least one RFID tag location of said one of said at least one RFID tag as being outside the predefined region having said associated boundary.

22. The method of claim 1 including a third determining step, said third determining step including determining a traversal rate associated with said one of said at least one RFID tag, said traversal rate corresponding to a rate of traversal of said RFID tag across at least one of the plurality of predefined regions within said environment, and wherein said first determining step includes determining a resolution of at least one of the plurality of sub-regions based upon the traversal rate associated with said RFID tag.

23. The method of claim 1 including a third determining step, said third determining step including determining a traversal rate associated with said one of said at least one RFID tag, said traversal rate corresponding to a rate of traversal of said RFID tag across at least one of the plurality of predefined regions within said environment, and including a fourth determining step, said fourth determining step including determining at least one specified time interval for receiving said RFID tag data from said RFID tag, at said one of said at least one RF receiver, based upon at least one of the traversal rate associated with said RFID tag and the RF coverage zone associated with said one of said at least one RF receiver.

24. The method of claim 23 wherein said receiving step includes receiving, at said one of said at least one RF receiver, said RFID tag data from said one of said at least one RFID tag during said at least one specified time interval.

25. The method of claim 23 including the step of filtering out old RFID tag data that was received at said one of said at least one RF receiver before a predetermined time point.

26. The method of claim 25 including the step of generating said predetermined time point based upon a multiple of the specified time interval for receiving said RFID tag data.

27. The method of claim 1 including a third determining step, said third determining step including determining a traversal rate associated with said one of said at least one RFID tag, said traversal rate corresponding to a rate of traversal of said RFID tag across at least one of the plurality of predefined regions within said environment, wherein said method further includes a fourth determining step, said fourth determining step including determining a specified time interval for interrogating said at least one RFID tag based upon the traversal rate associated with said RFID tag, and wherein said method further includes the step of transmitting at least one RF interrogation signal during the specified time interval by at least one RF interrogator.

28. The method of claim 1 including the steps of assigning a priority to said at least one RFID tag with reference to at least one of said plurality of predefined regions within said environment, and processing the RFID tag data received from said one of said at least one RFID tag based upon the priority of said one of said at least one RFID tag with reference to said at least one predefined region.

29. The method of claim 1 wherein said at least one RF receiver or at least one RF interrogator comprises a plurality of RF receivers or RF interrogators, wherein said first determining step includes determining the plurality of sub-regions, each sub-region corresponding to at least a portion of at least one of the plurality of RF coverage zones, and wherein each RF coverage zone is associated with at least one of the plurality of RF receivers or RF interrogators.

30. The method of claim 29 including the step of generating co-interrogation information indicative of at least two of said plurality of RF receivers or RF interrogators having overlapping RF coverage zones that correspond to at least one of the plurality of sub-regions.

31. The method of claim 30 including the step of representing said co-interrogation information in a matrix format.

32. The method of claim 29 including the step of generating sub-region resolution information indicative of at least one of the plurality of sub-regions being disposed within at least one RF coverage zone of at least one of the plurality of RF receivers or RF interrogators.

33. The method of claim 32 including the step of representing said sub-region resolution information in a matrix format.

34. The method of claim 1 wherein at least one RFID tag is located at a fixed location within said environment, and wherein said method further includes the step of receiving, at said at least one RF receiver, RFID tag data from said at least one RFID tag located at the fixed location, and determining the RF coverage zone associated with said at least one RF receiver or at least one RF interrogator with reference to the fixed location of said at least one RFID tag within said environment.

35. The method of claim 1 including the step of modeling said at least one RF receiver or at least one RF interrogator within said environment, and determining the RF coverage zone associated with said at least one RF receiver or at least one RF interrogator based upon the modeling of said at least one RF receiver or at least one RF interrogator within said environment.

36. The method of claim 1 further including the step of transmitting at least one RF interrogation signal for interrogating said at least one RFID tag by said at least one RF interrogator, and wherein said at least one RF interrogator has an associated RF coverage zone within which said RF interrogation signal can be received by said at least one RFID tag.

37. The method of claim 36 wherein at least one RFID tag is located at a fixed location within said environment, wherein said transmitting step includes transmitting said at least one RF interrogation signal for interrogating said at least one RFID tag located at the fixed location, and wherein said method further includes the step of determining the RF coverage zone associated with said at least one RF interrogator with reference to the fixed location of said at least one RFID tag.

38. The method of claim 36 wherein at least one RFID tag is located at a fixed location within said environment, wherein said at least one RF interrogator has an associated interrogation range, wherein said transmitting step includes transmitting said at least one RF interrogation signal for interrogating said at least one RFID tag located at the fixed location, and wherein said method further includes the step of determining the interrogation range associated with said at least one RF interrogator with reference to the fixed location of said at least one RFID tag.

39. The method of claim 1 wherein said at least one RF receiver comprises a plurality of RF receivers, and wherein said receiving step includes receiving, at each of the plurality of RF receivers, said RFID tag data from said one of said at least one RFID tag.

40. The method of claim 39 wherein said receiving step includes receiving, at each of the plurality of RF receivers at a respective time point, said RFID tag data from said one of said at least one RFID tag, wherein said method includes a third determining step, said third determining step including determining at least one time difference between the respective time points at which the RF receivers receive said RFID tag data, and wherein said second determining step includes determining said at least one RFID tag location of said one of said at least one RFID tag within the environment based at least in part upon said at least one time difference between the respective time points at which the RF receivers receive said RFID tag data.

41. The method of claim 39 wherein said receiving step includes receiving, at each of the plurality of RF receivers at a respective time point, said RFID tag data from at least one RFID tag, wherein said method includes a third determining step, said third determining step including determining at least one time difference between the respective time points at which the RF receivers receive said RFID tag data, and wherein said method includes a fourth determining step, said fourth determining step including determining at least one trajectory of said at least one RFID tag within the environment based upon said at least one time difference between the respective time points at which the RF receivers receive said RFID tag data.

42. The method of claim 39 wherein said second mapping step includes mapping the RFID tag data received at each of the plurality of RF receivers to said at least one of the sub-regions within the environment, wherein said second determining step includes determining a plurality of RFID tag locations of said one of said at least one RFID tag with reference to the predefined regions within the environment based upon the mapping of the RFID tag data received at each of the plurality of RF receivers to said at least one of the sub-regions and the mapping of the sub-regions to the predefined locations, and wherein said method further includes the step of correlating the plurality of RFID tag locations to generate at least one confidence estimate of the RFID tag location determinations.

43. The method of claim 1 wherein said at least one RFID tag includes a plurality of RFID tags, wherein said receiving step includes receiving, at said one of said at least one RF receiver, RFID tag data from each of the plurality of RFID tags, and wherein said second determining step includes determining at least one RFID tag location of each of the plurality of RFID tags.

44. The method of claim 43 wherein said receiving step includes receiving, at said one of said at least one RF receiver within at least one specified time interval, RFID tag data from each of the plurality of RFID tags, and wherein said method further includes the step of, in the event each of said at least one RFID tag location of each of the plurality of RFID tags corresponds to a respective one of the plurality of predefined regions, associating the plurality of RFID tags with at least one predefined element within said environment.

45. The method of claim 44 wherein said associating step includes logically associating the plurality of RFID tags with said at least one predefined element within the environment.

46. The method of claim 44 wherein said associating step includes associating locations of the plurality of RFID tags with a location of said at least one predefined element within the environment.

47. The method of claim 44 wherein said at least one predefined element comprises a plurality of predefined elements within said environment, and wherein said associating step includes hierarchically associating the plurality of RFID tags with said plurality of predefined elements within the environment.

48. The method of claim 44 including said step of associating the plurality of RFID tags with said at least one predefined element within said environment, wherein said at least one predefined element comprises at least one physical element selected from the group consisting of a container, a carrier, a conveyor, a vehicle, an individual, a machine, an article, a material, and a document.

49. The method of claim 44 including said step of associating the plurality of RFID tags with said at least one predefined element within said environment, wherein said at least one predefined element comprises at least one virtual element selected from the group consisting of a virtual container, a virtual carrier, a virtual conveyor, a virtual vehicle, a virtual individual, a virtual machine, a virtual article, a virtual material, and a virtual document.

50. The method of claim 1 including the steps of obtaining a representation of a physical space in which said at least one RF receiver or at least one RF interrogator are to be deployed, and specifying said plurality of predefined regions within said representation of said physical space.

51. The method of claim 50 wherein said first mapping step includes specifying said plurality of sub-regions within said representation of said physical space so that at least a portion of at least one of said plurality of predefined regions is within at least one of said specified plurality of sub-regions.

52. The method of claim 51 including the step of compiling, by said processor into at least one data file, information derived from said specifying of said plurality of predefined regions and said specifying of said plurality of sub-regions within said representation of said physical space, for use in controlling said at least one RF receiver or at least one RF interrogator.

53. A radio frequency identification (RFID) system, said RFID system being deployed in an environment, comprising:

a plurality of RF interrogators and a plurality of RF receivers, each of said plurality of RF interrogators being operative to transmit RF interrogation signals to at least one RFID tag, and each of said plurality of RF receivers being operative to receive RF signals containing RFID tag data from at least one RFID tag,

wherein each of said plurality of RF receivers and said plurality of RF interrogators has an RF coverage zone associated therewith, each RF coverage zone corresponding to a region within said environment;

at least one data storage; and

at least one controller communicably coupled to said plurality of RF interrogators, said plurality of RF receivers, and said at least one data storage, said at least one controller including at least one processor and at least one memory, said at least one controller being operative;

to determine a plurality of sub-regions within said environment, each sub-region corresponding to at least a portion of at least one RF coverage zone associated with at least one RF receiver or at least one RF interrogator;

to map said plurality of sub-regions to a plurality of predefined regions within said environment;

to store, in said at least one data storage, information defining the mapping of said plurality of sub-regions to said plurality of predefined regions within said environment;

to receive RFID tag data from one of said plurality of RF receivers;

to map the received RFID tag data to at least one of said plurality of sub-regions based at least upon the RF coverage zone associated with the respective RF receiver that received said RFID tag data from the respective RFID tag, or the RF coverage zone associated with the respective RF interrogator that transmitted the RF interrogation signal to the respective RFID tag; and

to determine, using the mapping of said RFID tag data to said at least one of said plurality of sub-regions and the stored information defining the mapping of said plurality of sub-regions to said plurality of predefined regions, an RFID tag location of the respective RFID tag with reference to said plurality of predefined regions within said environment;

to determine a plurality of RFID tag locations of said at least one RFID tag within the environment;

to determine a first plurality of likelihood estimates of said at least one RFID tag being located at the plurality of RFID tag locations, respectively;

to determine a first maximum of the first plurality of likelihood estimates;

to determine a single RFID tag location of said at least one RFID tag based upon said first maximum likelihood determination;

to determine a second plurality of likelihood estimates of said at least one RFID tag being located at the plurality of sub-regions, respectively;

to determine a second maximum of the second plurality of likelihood estimates;

to determine the single RFID tag location of said at least one RFID tag based at least in part upon said second maximum likelihood determination;

to determine at least one region of overlap of said plurality of RF coverage zones associated with said plurality of RF receivers or RF interrogators, respectively;

to identify at least one set of RF receivers or RF interrogators having RF coverage zones corresponding to said at least one region of overlap of said plurality of RF coverage zones,

to identify at least one of the plurality of sub-regions within said environment corresponding to said at least one region of overlap of said plurality of RF coverage zones;

to determine the second plurality of likelihood estimates of said at least one RFID tag being located at the plurality of sub-regions, respectively, based upon said at least one identified set of RF receivers or RF interrogators and said at least one identified sub-region; and

to determine a probability band P disposed around each RF receiver or RF interrogator, said probability band P being expressed as

P(<

T,R,t>

|T at x),

wherein “

T”

is an identifier of one of said at least one RFID tag, “

R”

is an identifier of the respective RF receiver or RF interrogator, “

t”

corresponds to a timestamp indicative of a most recent time point of RFID tag data reception or RFID tag interrogation, “

x”

represents a respective one of the plurality of sub-regions, and said probability band P expressed as “

P(<

p>

|T at x)”

corresponds to the likelihood of said RFID tag data from said RFID tag having the first identifier T being observed when said RFID tag T is located at said sub-region x.

54. The system of claim 53 wherein said at least one controller is operative to map the plurality of sub-regions to a selected one of a plurality of sets of predefined regions within said environment, said selected set of predefined regions being associated with at least one software application, and wherein said system further includes at least one computer operative to execute said at least one software application, said at least one computer being communicably coupled to said at least one controller, said at least one controller being operative to generate RFID tag location data corresponding to said at least one RFID tag location, and to provide said RFID tag location data to said at least one computer executing said at least one software application, said at least one software application being configured to receive said RFID tag location data as input, and to process said RFID tag location data with reference to said selected set of predefined regions associated therewith.

55. The system of claim 54 wherein said RFID tag location data includes one or more of an identifier of one of said at least one RFID tag location, an identifier of one of said at least one RFID tag, an identifier of one of said at least one RF receiver, and a timestamp indicative of a most recent time point when said RFID tag data was received at said one of said at least one RF receiver.

56. The system of claim 53 wherein said at least one controller is operative to determine at least one likelihood estimate of said at least one RFID tag being located at said at least one RFID tag location.

57. The system of claim 53 wherein said at least one controller is operative to determine at least one likelihood estimate of said at least one RFID tag being located at said at least one of the plurality of sub-regions within said environment.

58. The system of claim 53 wherein said at least one controller is operative to determine at least one likelihood estimate of said RFID tag data from said at least one RFID tag being received at the respective RF receiver, or at least one likelihood estimate of the RF interrogation signal transmitted by the respective RF interrogator being received at said one of said at least one RFID tag.

59. The system of claim 53 wherein said at least one controller is operative to generate an ordered sequence of the first plurality of likelihood estimates, and to determine the plurality of RFID tag locations of said at least one RFID tag based upon said ordered sequence of likelihood estimates.

60. The system of claim 53 wherein said at least one controller is operative to determine the second maximum of the second plurality of likelihood estimates by comparing each of the second plurality of likelihood estimates to a predetermined threshold value.

61. The system of claim 53 wherein said at least one controller is operative to determine the probability band P disposed around each RF receiver or RF interrogator, and wherein said probability band P is expressed as

P(<

T,R,t>

|T at x)≧

PROB_THRESH,

wherein “

PROB_THRESH”

is a specified threshold value.

62. The system of claim 53 wherein said at least one controller is operative to determine the probability band P disposed around each RF receiver or RF interrogator, and wherein said probability band P disposed around the respective RF receiver or RF interrogator corresponds to the RF coverage zone of the respective RF receiver or RF interrogator.

63. The system of claim 53 wherein said at least one RF receiver is operative to receive RFID tag data from a plurality of RFID tags disposed within said at least one region corresponding to said at least one RF coverage zone associated with said at least one RF receiver or at least one RF interrogator, and wherein said at least one controller is operative to generate information <

T,R,t>

for each of said plurality of RFID tags, to determine whether identical information <

T,R,t>

is generated for at least two of the plurality of RFID tags, to designate RFID tag data from at least one of said at least two RFID tags as redundant RFID tag data in the event identical information <

T,R,t>

is generated for at least two of the plurality of RFID tags, and to filter out said redundant RFID tag data.

64. The system of claim 63 wherein said at least one controller is operative to filter out said redundant RFID tag data during at least one specified time interval.

65. The system of claim 64 wherein said at least one controller is operative to filter out old RFID tag data having at least one corresponding timestamp t indicating that said old RFID tag data was received at the respective RF receiver before a predetermined time point.

66. The system of claim 65 wherein said predetermined time point is based upon a multiple of the specified time interval for filtering out the redundant RFID tag data.

67. The system of claim 53 wherein said at least one RF receiver or at least one RF interrogator corresponds to a respective logical RF receiver or RF interrogator, the respective logical RF receiver or RF interrogator having an associated operating profile.

68. The system of claim 67 wherein said operating profile associated with the respective logical RF receiver or RF interrogator includes information selected from the group consisting of a sensitivity level, an operating mode, an RFID air protocol, and a direction of at least one antenna associated with the RF receiver or RF interrogator corresponding to the respective logical RF receiver or RF interrogator.

69. The system of claim 67 wherein said RF coverage zone associated with said at least one RF receiver or at least one RF interrogator corresponding to the respective logical RF receiver or RF interrogator is based at least in part upon the operating profile of the respective logical RF receiver or RF interrogator.

70. The system of claim 53 wherein each of the plurality of predefined regions within said environment has at least one associated boundary, wherein said at least one controller is operative to map the plurality of sub-regions to the plurality of predefined regions, and wherein at least one of the mapped sub-regions extends across at least one boundary associated with at least one of the plurality of predefined regions.

71. The system of claim 70 wherein said at least one controller is operative, in the event the received RFID tag data is mapped to said at least one sub-region extending across said at least one boundary associated with said at least one of the plurality of predefined regions, to determine said at least one RFID tag location of said at least one RFID tag as being within the predefined region having said associated boundary.

72. The system of claim 70 wherein said at least one controller is operative, in the event the received RFID tag data is mapped to said at least one sub-region extending across said at least one boundary associated with said at least one of the plurality of predefined regions, to determine said at least one RFID tag location of said at least one RFID tag as being outside the predefined region having said associated boundary.

73. The system of claim 53 wherein said at least one controller is operative to determine at least one traversal rate associated with at least one RFID tag, said traversal rate corresponding to a rate of traversal of said at least one RFID tag across at least one of the plurality of predefined regions within said environment, and wherein said at least one controller is operative to determine a resolution of at least one of the plurality of sub-regions based upon the traversal rate associated with said at least one RFID tag.

74. The system of claim 53 wherein said at least one controller is operative to determine at least one traversal rate associated with at least one RFID tag, said traversal rate corresponding to a rate of traversal of said RFID tag across at least one of the plurality of predefined regions within said environment, and wherein said at least one controller is operative to determine a specified time interval for receiving said RFID tag data from said at least one RFID tag at said at least one RF receiver based upon at least one of the traversal rate associated with said at least one RFID tag and the RF coverage zone associated with said at least one RF receiver or at least one interrogator.

75. The system of claim 74 wherein said at least one controller is operative to filter out old RFID tag data that was received at said at least one RF receiver before a predetermined time point.

76. The system of claim 75 wherein said predetermined time point is based upon a multiple of said specified time interval for receiving said RFID tag data from said at least one RFID tag at said at least one RF receiver.

77. The system of claim 53 wherein said at least one controller is operative to determine at least one traversal rate associated with at least one RFID tag, said traversal rate corresponding to a rate of traversal of said RFID tag across at least one of the plurality of predefined regions within said environment, wherein said at least one RF interrogator is operative to transmit at least one RF interrogation signal for interrogating at least one RFID tag, wherein said at least one controller is operative to determine a specified time interval for interrogating said at least one RFID tag by said at least one RF interrogator based upon the traversal rate associated with said at least one RFID tag, and wherein said at least one RF interrogator is operative to transmit said at least one RF interrogation signal during the specified time interval.

78. The system of claim 53 wherein said at least one controller is operative to assign a priority to said at least one RFID tag with reference to at least one of said plurality of predefined regions within said environment, and to process the RFID tag data received from said at least one RFID tag based upon the priority of said at least one RFID tag with reference to said at least one predefined region.

79. The system of claim 53 wherein said at least one RF receiver or at least one RF interrogator comprises a plurality of RF receivers or RF interrogators, each of the plurality of RF receivers or RF interrogators having an associated RF coverage zone, and wherein said at least one controller is operative to determine said plurality of sub-regions, wherein each sub-region corresponds to at least a portion of at least one of the RF coverage zones associated with the plurality of RF receivers or RF interrogators.

80. The system of claim 79 wherein said at least one controller is operative to generate co-interrogation information indicative of at least two of said plurality of RF receivers or RF interrogators having overlapping RF coverage zones that correspond to at least one of the plurality of sub-regions.

81. The system of claim 79 wherein said at least one controller is operative to generate sub-region resolution information indicative of at least one of the plurality of sub-regions being disposed within at least one RF coverage zone of at least one of the plurality of RF receivers or RF interrogators.

82. The system of claim 53 wherein at least one RFID tag is located at a fixed location within said environment, wherein said at least one RF receiver is operative to receive RFID tag data from said at least one RFID tag located at the fixed location, and wherein said at least one controller is operative to determine the RF coverage zone associated with said at least one RF receiver with reference to the fixed location of said at least one RFID tag within said environment.

83. The system of claim 53 wherein said at least one controller is operative to model said at least one RF receiver or at least one RF interrogator within said environment, and to determine the RF coverage zone associated with said at least one RF receiver or at least one RF interrogator based upon the modeling of said at least one RF receiver or at least one interrogator within said environment.

84. The system of claim 53 wherein at least one RFID tag is located at a fixed location within said environment, wherein said at least one RF interrogator is operative to transmit at least one RF interrogation signal for interrogating said at least one RFID tag located at said fixed location, wherein said at least one RF receiver is operative to receive RFID tag data from said at least one RFID tag located at said fixed location in response to being interrogated by said at least one RF interrogator, and wherein said at least one controller is operative to determine the RF coverage zone associated with said at least one RF interrogator with reference to the fixed location of said at least one RFID tag.

85. The system of claim 53 wherein at least one RFID tag is located at a fixed location within said environment, wherein said at least one RF interrogator has an associated interrogation range, wherein said at least one RF interrogator is operative to transmit at least one RF interrogation signal for interrogating said at least one RFID tag located at the fixed location, and wherein said at least one controller is operative to determine the interrogation range associated with said at least one RF interrogator with reference to the fixed location of said at least one RFID tag.

86. The system of claim 53 wherein said at least one RF receiver comprises a plurality of RF receivers, wherein each of said plurality of RF receivers is operative to receive, at a respective time point, RFID tag data from said at least one RFID tag, and wherein said at least one controller is operative to determine at least one time difference between the respective time points at which the RF receivers receive said RFID tag data, and to determine said at least one RFID tag location of said at least one RFID tag within the environment based at least in part upon said at least one time difference between the respective time points at which the RF receivers receive said RFID tag data.

87. The system of claim 53 wherein said at least one RF receiver comprises a plurality of RF receivers, wherein each of said plurality of RF receivers is operative to receive, at a respective time point, RFID tag data from at least one RFID tag, and wherein said at least one controller is operative to determine at least one time difference between the respective time points at which the RF receivers receive said RFID tag data, and to determine at least one trajectory of said at least one RFID tag within the environment based upon said at least one time difference between the respective time points at which the RF receivers receive said RFID tag data.

88. The system of claim 53 wherein said at least one RF receiver comprises a plurality of RF receivers, wherein said at least one controller is operative to map the RFID tag data received at each of the plurality of RF receivers to said at least one of the sub-regions within the environment, to determine a plurality of RFID tag locations of said at least one RFID tag with reference to the predefined regions within the environment based upon the mapping of the RFID tag data received at each of the plurality of RF receivers to said at least one of the sub-regions and the mapping of the sub-regions to the predefined regions, and to correlate the plurality of RFID tag locations for generating at least one confidence estimate of the RFID tag location determinations.

89. The system of claim 53 wherein said at least one RFID tag includes a plurality of RFID tags, wherein said at least one RF receiver is operative to receive RFID tag data from each of the plurality of RFID tags, and wherein said at least one controller is operative to determine at least one RFID tag location of each of the plurality of RFID tags.

90. The system of claim 89 wherein said at least one RF receiver is operative to receive, within a specified time interval, said RFID tag data from each of the plurality of RFID tags, and wherein said at least one controller is operative to, in the event each of said at least one RFID tag location of each of the plurality of RFID tags corresponds to a respective one of the plurality of predefined regions, to associate the plurality of RFID tags with at least one predefined element within said environment.

91. The system of claim 90 wherein said at least one predefined element is selected from the group consisting of a container, a carrier, a conveyor, a vehicle, an individual, a machine, an article, a material, and a document.

92. The system of claim 53 wherein said at least one controller is operative to obtain a representation of a physical space in which said at least one RF receiver or at least one RF interrogator, and said at least one controller are to be deployed, and to specify said plurality of predefined regions within said representation of said physical space.

93. The system of claim 92 wherein said at least one controller is operative to specify said plurality of sub-regions within said representation of said physical space so that at least a portion of said plurality of predefined regions is within at least one of said specified plurality of sub-regions.

94. The system of claim 93 wherein said at least one controller is operative to compile information derived from said specifying of said plurality of predefined regions and said specifying of said plurality of sub-regions within said representation of said physical space into at least one data file, for use in controlling said at least one RF receiver or at least one RF interrogator.