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Communication and distance measurement in an addressed wide band RFID system

  • US 8,193,913 B2
  • Filed: 09/12/2005
  • Issued: 06/05/2012
  • Est. Priority Date: 09/13/2004
  • Status: Active Grant
First Claim
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1. In a radio frequency identification system of elements including at least one reader and a plurality of tags, including a first tag and a second tag, a method for communicating between the at least one reader and the tags, the method comprising:

  • addressing a wide-band-message signal by including in said signal a first-tag identifier of the first tag, thereby producing an addressed wide-band-message signal with a destination being the first tag along with other tag identifiers for respective other tags forming a first set of addressed tags;

    transmitting said addressed wide-band-message signal by the reader;

    determining a probability of collision for the addressed wide-band-message signal transmitted relative to a threshold and not conducting transmission of an additional addressed wide-band-message signal responsive to the probability of collision being below the threshold;

    transmitting the additional addressed wide-band-message signal addressed for a second set of addressed tags responsive to the probability of collision exceeding the threshold, the second set of addressed tags being a smaller set of tags than the first set of addressed tags;

    waiting to receive by the first tag said addressed wide-band-message signal; and

    upon receiving said addressed wide-band message signal and recognizing said identifier, responding to said addressed wide-band-message signal by transmitting by the first tag an addressed wide-band response signal.

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