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Robust downlink frame synchronization schemes in CDMA wireless networks for geo-location

  • US 8,331,955 B2
  • Filed: 12/28/2010
  • Issued: 12/11/2012
  • Est. Priority Date: 12/28/2010
  • Status: Active Grant
First Claim
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1. A method for use by a wireless location system (WLS) associated with a CDMA-based wireless communications network (WCN), comprising:

  • receiving, at a first location measuring unit (LMU), a CDMA downlink signal broadcast by a sector of a base station;

    determining, by the first LMU, sector timing information for the sector in response to synchronizing with the downlink signal, wherein the determination of sector timing information comprises,determining slot timing information from a received downlink primary synchronization channel;

    determining frame timing information and a scrambling code group for the sector from a received secondary synchronization channel;

    determining a scrambling code for the sector from the scrambling code group for the sector and a downlink common pilot channel for the sector; and

    determining a frame number and a sector identifier for the sector;

    sending the sector timing information from the first LMU to a second LMU;

    receiving, at the first and second LMUs, uplink signals from a mobile device communicating with the sector of the base station;

    determining, at the first and second LMUs, time of arrival information for the uplink signals received at the first and second LMUs using the sector timing information; and

    determining a geographic location of the mobile device using the time of arrival information.

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