RFID tag parameter estimation using read difficulty factor
First Claim
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1. A method for a Radio Frequency Identification (RFID) system, comprising:
- inventorying an RFID tag to obtain an item identifier (II) indicating an item to which the tag is attached;
determining at least one read metric, wherein the at least one read metric is determined from at least one of a tag response and a reader state;
retrieving, based on the II, a read difficulty factor (RDF), wherein the RDF indicates how the item modifies a readability of the tag and was stored prior to the inventorying; and
estimating a parameter based on the at least one read metric and the RDF, wherein the parameter is at least one of a tag velocity, a tag motion direction, and a tag distance from a reader antenna, and estimating the parameter includes updating the at least one read metric based on the RDF.
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Abstract
A Radio Frequency Identification (RFID) system uses read difficulty factors (RDFs) to improve tag-parameter estimation. During inventory, a reader can obtain a tag'"'"'s item identifier (II), determine a read metric such as a received signal strength indicator (RSSI), retrieve an RDF associated with the II, and adjust the RSSI using the RDF to more accurately estimate a tag parameter such as distance from the reader antenna. The system can then use the estimated distance to categorize the tag.
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Citations
17 Claims
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1. A method for a Radio Frequency Identification (RFID) system, comprising:
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inventorying an RFID tag to obtain an item identifier (II) indicating an item to which the tag is attached; determining at least one read metric, wherein the at least one read metric is determined from at least one of a tag response and a reader state; retrieving, based on the II, a read difficulty factor (RDF), wherein the RDF indicates how the item modifies a readability of the tag and was stored prior to the inventorying; and estimating a parameter based on the at least one read metric and the RDF, wherein the parameter is at least one of a tag velocity, a tag motion direction, and a tag distance from a reader antenna, and estimating the parameter includes updating the at least one read metric based on the RDF. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A Radio Frequency Identification (RFID) system, comprising:
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a communication module configured to communicate wirelessly with an RFID tag; a memory; and a processing block configured to; inventory the RFID tag to obtain an item identifier (II) indicating an item to which the tag is attached; determine at least one read metric, wherein the at least one read metric is determined from at least one of a tag response and a reader state; retrieve, based on the II, a read difficulty factor (RDF), wherein the RDF indicates how the item modifies a readability of the tag and was stored prior to the inventorying; and estimate a parameter based on the at least one read metric and the RDF, wherein the parameter is at least one of a tag velocity, a tag motion direction, and a tag distance from a reader antenna, and wherein the processing block is configured to employ the parameter in determining an item category using a read-category algorithm. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An Radio Frequency Identification (RFID) reader, comprising:
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a communication module configured to communicate wirelessly with an RFID tag; a memory; and a processing block configured to; inventory the RFID tag to obtain an item identifier (II) indicating an item to which the tag is attached; determine at least one read metric, wherein the at least one read metric is determined from at least one of a tag response and a reader state; retrieve, based on the II, a read difficulty factor (RDF), wherein the RDF indicates how the item modifies a readability of the tag and was stored prior to the inventorying; estimate a parameter based on the at least one read metric and the RDF, wherein the parameter is tag distance from the reader antenna; and determine a category for the tag by applying a threshold to the estimated parameter. - View Dependent Claims (16, 17)
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Specification