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; and
detecting at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if at least a partial response is received.
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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
34 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; and
detecting at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if at least a partial response is received. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 17)
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- 10. The method of claim 10 wherein the step of detecting at least one radio frequency identification tag comprises analyzing the received response and determining whether a valid start-of-frame (SOF) field was received.
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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; and
detect at least one radio frequency identification tag having the selected value in the specified memory location in the interrogation corridor if at least a partial response is received. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. A method comprising:
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detecting a collision between communications from radio frequency identification tags in an interrogation corridor; and
generating an alarm upon detecting the collision to indicate that an unauthorized article is present within the interrogation corridor.
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32. A method comprising:
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receiving a partial response from a radio frequency identification tag in an interrogation corridor; and
generating an alarm upon receiving the partial response to indicate that an unauthorized article is present within the interrogation corridor. - View Dependent Claims (33, 34)
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Specification