Method, system, and apparatus for communicating with a RFID tag population
First Claim
1. A radio frequency identification (RFID) tag device, comprising:
- an antenna that receives an electromagnetic carrier signal;
a receiver coupled to the antenna, wherein the receiver is configured to recover a symbol on the carrier signal; and
a modulator coupled to the antenna, wherein the modulator is configured to receive a response value, and is configured to backscatter modulate the carrier signal with a single frequency during a plurality of time periods based on the response value.
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Accused Products
Abstract
A method, system, and apparatus for communicating with a radio frequency identification (RFID) tag population that includes one or more tags are described. The tags are interrogated by a reader which may be located in a network of readers. The reader interrogates the tags by transmitting data symbols to the tags. Tags respond to the reader with backscatter symbols. Bit patterns, such as identification numbers stored in the tags, are collected from the plurality of tags without collisions. Collisions are avoided because the backscatter symbols transmitted by the tags use different characteristics to represent different data bits. For example, a first backscatter symbol frequency is used by the tag to represent a “0” bit, and a second backscatter symbol frequency is used by the tag to represent a “1” bit.
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Citations
21 Claims
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1. A radio frequency identification (RFID) tag device, comprising:
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an antenna that receives an electromagnetic carrier signal; a receiver coupled to the antenna, wherein the receiver is configured to recover a symbol on the carrier signal; and a modulator coupled to the antenna, wherein the modulator is configured to receive a response value, and is configured to backscatter modulate the carrier signal with a single frequency during a plurality of time periods based on the response value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A reader that communicates with a radio frequency identification (RFID) tag device, comprising:
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a transmitter that transmits a radio frequency carrier signal; a receiver that receives the carrier signal that is backscatter modulated with a single frequency during a plurality of time periods by a tag device; and a logic module that determines a data value of the backscatter modulated carrier signal by determining a characteristic of the single frequency during each of the plurality of time periods. - View Dependent Claims (14, 15)
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16. A method for communicating in a radio frequency identification (RFID) tag, comprising:
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receiving an electromagnetic carrier signal modulated with a symbol; demodulating the carrier signal to recover the symbol; determining a response value for a response to the recovered symbol; and backscatter modulating the carrier signal with a single frequency during a plurality of time periods in a manner based on the response value. - View Dependent Claims (17, 18)
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19. A method in a reader to communicate with a radio frequency identification (RFID) tag device, comprising:
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transmitting a radio frequency carrier signal; receiving the carrier signal, wherein the received carrier is backscatter modulated with a single frequency during a plurality of time periods by a tag device; and determining a data value of the backscatter modulated carrier signal by determining a characteristic of the single frequency during each of the plurality of time periods. - View Dependent Claims (20, 21)
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Specification