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Estimation of speed and direction of travel in a WLAN positioning system using multiple position estimations

  • US 7,551,929 B2
  • Filed: 05/08/2006
  • Issued: 06/23/2009
  • Est. Priority Date: 05/08/2006
  • Status: Active Grant
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1. A method for facilitating the determination of a speed of travel of the Wi-Fi enabled device within a location-based services system having a reference database of Wi-Fi access points in a target area, each Wi-Fi access point in the target area positioned at a corresponding geographical location, the method comprising:

  • the Wi-Fi enabled device receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device during a window of time;

    accessing the reference database to retrieve the corresponding geographical locations of the identified Wi-Fi access points;

    using the geographical locations of the identified Wi-Fi access points to estimate a plurality of positions of the Wi-Fi enabled device occurring during the window of time;

    associating a time value with each of the estimated positions, each time value and position estimate forming one position/time pair of a plurality of pairs, the plurality having a first position occurring at a first time and a second position occurring at a second time;

    calculating a lower speed bound based on a difference between the first position and time and second position and time;

    calculating a plurality of speeds based on differences between consecutive pairs of the plurality of position/time pairs;

    selecting as an upper speed bound the median speed from the plurality of speeds; and

    calculating a speed of travel of the Wi-Fi enabled device based on the median speed of the plurality of speeds and the first speed.

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