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Wireless node location mechanism responsive to observed propagation characteristics of wireless network infrastructure signals

  • US 7,205,938 B2
  • Filed: 03/05/2004
  • Issued: 04/17/2007
  • Est. Priority Date: 03/05/2004
  • Status: Active Grant
First Claim
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1. A method facilitating the location of a wireless node in an RF environment, the RF environment including a plurality of radio transceivers placed in known locations, comprising:

  • detecting, at the known locations of the plurality of radio transceivers, the strength of RF signals transmitted by the plurality of radio transceivers;

    receiving a request to locate a wireless node;

    selecting radio transceivers that detect RF signals transmitted by the wireless node;

    then, for pairs of the selected radio transceivers;

    determining a distance between a first and second radio transceiver, wherein the first and second radio transceivers detected RF signals from each other in the detecting step;

    determining an observed path loss between the first and second radio transceivers; and

    computing a path loss exponent based on the determined distance and the observed path loss; and

    then, for each selected radio transceiver, computing an average path loss exponent based on all path loss exponents associated with a respective radio transceiver; and

    estimating the location of the wireless node based on respective estimated distances between the selected radio transceivers and the wireless node, wherein the respective estimated distances are determined according to a path loss model using the average path loss exponents corresponding to a given radio transceiver and the strength of the RF signal transmitted by the wireless node and detected by the given radio transceiver.

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