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Method and apparatus for an arbitration scheme for radio frequency identification devices

  • US 7,639,638 B2
  • Filed: 05/02/2006
  • Issued: 12/29/2009
  • Est. Priority Date: 02/19/1998
  • Status: Expired due to Fees
First Claim
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1. A method comprising:

  • sending a first command from an interrogator to a plurality of wireless identification devices to select a first subset of the plurality of wireless identification devices in accordance with an arbitration scheme, the first subset associated with a first branch of a search tree corresponding to a tree search scheme, the first command requesting each of the plurality of wireless identification devices of the first subset to respond approximately simultaneously;

    sending a second command from the interrogator to the plurality of wireless identification devices to select a second subset of the plurality of wireless identification devices in accordance with the arbitration scheme, the second subset associated with a second branch of the search tree, the second command requesting each of the plurality of wireless identification devices of the second subset to respond in an independently selected one of a plurality of time slots in accordance with an Aloha scheme;

    detecting a collision between at least two wireless identification devices of the plurality of wireless identification devices; and

    skipping at least one level of the search tree in response to detecting the collision.

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