Detecting a Departure of an RFID Tag from an Area
First Claim
1. A method of determining whether a radio frequency identifier (RFID) tag has been removed from an area comprising:
- responsive to detecting an RFID tag in a first area, making an entry within a tag read cache associated with the first area, wherein the entry within the tag read cache comprises an identifier corresponding to the RFID tag and a timestamp indicating when the RFID tag was detected in the first area;
calculating a difference between a current time and the timestamp from the entry within the tag read cache; and
indicating that the RFID tag is no longer in the first area if the difference exceeds a departure threshold.
1 Assignment
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Accused Products
Abstract
A method of determining whether a radio frequency identifier (RFID) tag has been removed from an area can include, responsive to detecting an RFID tag in a first area, making an entry within a tag read cache associated with the first area. The entry within the tag read cache can include an identifier corresponding to the RFID tag and a timestamp indicating when the RFID tag was detected in the first area. A difference between a current time and the timestamp from the entry within the tag read cache can be calculated. An indication that the RFID tag is no longer in the first area can be provided if the difference exceeds a departure threshold.
28 Citations
20 Claims
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1. A method of determining whether a radio frequency identifier (RFID) tag has been removed from an area comprising:
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responsive to detecting an RFID tag in a first area, making an entry within a tag read cache associated with the first area, wherein the entry within the tag read cache comprises an identifier corresponding to the RFID tag and a timestamp indicating when the RFID tag was detected in the first area; calculating a difference between a current time and the timestamp from the entry within the tag read cache; and indicating that the RFID tag is no longer in the first area if the difference exceeds a departure threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining whether a radio frequency identifier (RFID) tag has been moved from an area, the method comprising:
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for each of a plurality of detected RFID tags, making a location cache entry comprising a location identifier specifying an area in which the RFID tag was detected; making a tag read cache entry in a tag read cache corresponding to the location cache entry, wherein the tag read cache entry comprises a tag identifier corresponding to the RFID tag and a timestamp indicating when the RFID tag was read in the area; identifying tag read cache entries having an age that exceeds a departure threshold as determined by a comparison of the timestamp specified by the tag read cache entries with a current time; and for each identified tag read cache entry, providing a notification that the RFID tag associated with that tag read cache entry is no longer in the area specified by the location cache entry which corresponds to the identified tag read cache entry. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A computer program product comprising:
a computer-usable medium having a computer-readable program that determines whether a radio frequency identifier (RFID) tag has been removed from an area, said computer program product including; computer-usable program code that, responsive to detecting an RFID tag in a first area, makes an entry within a tag read cache associated with the first area, wherein the entry within the tag read cache comprises an identifier corresponding to the RFID tag and a timestamp indicating when the RFID tag was detected in the first area; computer-usable program code that calculates a difference between a current time and the timestamp from the entry within the tag read cache; and computer-usable program code that indicates that the RFID tag is no longer in the first area if the difference exceeds a departure threshold. - View Dependent Claims (15, 16, 17, 18, 19, 20)
Specification