Algorithm for RFID security
First Claim
1. A method, comprising:
- selectively interrogating radio frequency identification tags in an interrogation corridor such that only those tags having a selected value in a specified memory location respond to the interrogation;
simultaneously receiving a response from all of the radio frequency identification tags having the selected value in the specified memory location;
detecting at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if only a valid partial response is received; and
indicating an alarm upon receiving only the valid partial response from at least one of the radio frequency identification tags having the selected value.
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Accused Products
Abstract
Techniques for detecting radio-frequency identification (RFID) tags are disclosed. For example, an exit control system is described that detects unauthorized removal of articles from a protected facility. A series of antennas are setup to produce interrogation corridors located near the exit of the protected area. RFID tags are attached to the articles to be protected. Each tag includes information that uniquely identifies the article to which it is affixed and status information as to whether the articles removal from the facility is authorized. The RF reader outputs RF signals through the antennas to create electromagnetic fields within the interrogation corridors. The reader outputs RF power from a single port to the multiple antennas via a splitter/combiner. In this way, a single RF reader with only one transmitter/receiver port simultaneously interrogates multiple antennas. A variety of techniques are described by which the reader can detect the removal of an unauthorized article.
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Citations
38 Claims
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1. A method, comprising:
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selectively interrogating radio frequency identification tags in an interrogation corridor such that only those tags having a selected value in a specified memory location respond to the interrogation; simultaneously receiving a response from all of the radio frequency identification tags having the selected value in the specified memory location; detecting at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if only a valid partial response is received; and indicating an alarm upon receiving only the valid partial response from at least one of the radio frequency identification tags having the selected value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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measuring a noise floor in an interrogation corridor when no radio frequency identification tags are present; selectively interrogating radio frequency identification tags in the interrogation corridor such that only those tags having a selected value in a specified memory location respond to the interrogation; receiving a signal representative of a possible response from one or more of the radio frequency identification tags having the selected value in the specified memory location; comparing the received signal with the noise floor to validate that the received possible response was produced by a checked-in radio frequency identification tag; and detecting at least one of the radio frequency identification tags having the selected value in the specified memory location in the interrogation corridor when the signal was produced by a checked-in radio frequency identification tag and at least a valid partial response is received. - View Dependent Claims (14, 15, 16, 17)
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18. A method, comprising:
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interrogating radio frequency identification tags in an interrogation corridor to identify presence of those tags having a selected value in a specified memory location; simultaneously receiving a response from all of the radio frequency identification tags in the interrogation corridor; detecting a collision in at least one bit of the specified memory location; and detecting at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if a collision is detected. - View Dependent Claims (19, 20, 21, 22)
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23. A computer-readable medium comprising instructions to cause a processor to:
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selectively interrogate radio frequency identification tags in an interrogation corridor such that only those tags having a selected value in a specified memory location respond to the interrogation; simultaneously receive a response from all of the radio frequency identification tags having the selected value in the specified memory location; detect at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if only a valid partial response is received; and indicating an alarm upon receiving only the valid partial response from at least one of the radio frequency identification tags having the selected value. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A method comprising:
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receiving only a partial response from a radio frequency identification tag in an interrogation corridor; and generating an alarm upon receiving only the partial response to indicate that an unauthorized article is present within the interrogation corridor. - View Dependent Claims (31, 32)
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33. A system comprising:
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a plurality of radio frequency (RF) antennas set up to provide art interrogation corridor, wherein the RF antennas interrogate radio frequency identification tags in the interrogation corridor; and a RF reader coupled to the plurality of antennas, wherein the RF reader simultaneously receives a response from all of the radio frequency identification tags in the interrogation corridor, detects whether a collision occurs in at least one bit of a specified memory location, and detects at least one radio frequency identification tag having a selected value in the specified memory location in the interrogation corridor upon detecting a collision. - View Dependent Claims (34, 35, 36, 37, 38)
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Specification