Method for simultaneously detecting a plurality of RFID tags using multiuser detection
First Claim
1. A method for distinguishing responses received by an RFID detector from a plurality of simultaneously queried RFID tags, the method comprising:
- querying the plurality of RFID tags;
receiving an aggregated RF response from the plurality of RFID tags; and
applying multiuser detection including jointly demodulating a plurality of colliding RFID tag responses included in the aggregated RF response according to at least one estimated parameter so as to distinguish each of the RFID tag responses included in the aggregated RF response.
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Abstract
A method and apparatus are disclosed that apply multiuser detection (MUD) analysis to an aggregated RF response from a plurality of simultaneously queried RFID tags, so as to distinguish the individual tag responses. The claimed method thereby significantly reduces RFID detection latency when multiple tags are simultaneously queried. Some embodiments transmit carrier waves at more than one frequency, such as a plurality of equally-spaced frequencies, so as to enhance the MUD analysis by incorporating a multi-frequency dimension. Other embodiments incorporate additional spatial dimensions by deploying multiple RF detection antennae at separated locations. The number of colliding tag responses must be estimated before MUD analysis can be applied. In some embodiments other signal parameters must be estimated, such as signal bias and an impulse function for each responding tag that characterizes alterations of the RF signal while in transit due to propagation distance, passage through intervening objects, and reflections.
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Citations
26 Claims
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1. A method for distinguishing responses received by an RFID detector from a plurality of simultaneously queried RFID tags, the method comprising:
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querying the plurality of RFID tags; receiving an aggregated RF response from the plurality of RFID tags; and applying multiuser detection including jointly demodulating a plurality of colliding RFID tag responses included in the aggregated RF response according to at least one estimated parameter so as to distinguish each of the RFID tag responses included in the aggregated RF response. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for distinguishing responses received from a plurality of simultaneously queried RFID tags, the apparatus comprising:
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an RF transmitter configured to transmit a querying RF signal to the plurality of RFID tags; an RF receiver configured to receive an aggregated RF response from the plurality of RFID tags; and a processor configured to apply multiuser detection including jointly demodulating a plurality of colliding RFID tag responses included in the aggregated RF response according to at least one estimated parameter, so as to distinguish each of the RFID tag responses included in the aggregated RF response. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification