METHOD FOR THE ACCELERATED ACQUISITION OF SATELLITE SIGNALS

• US 20070194985A1
• Filed: 12/28/2006
• Published: 08/23/2007
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: IDPA Holdings Incorporated (InterDigital, Inc.)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Monnerat, Michel
• Granted Patent: US 7,403,155 B2
• Time in Patent Office: Days
• US Class Current: 342/357.31
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data

Abstract

The present invention proposes to use optimally a location method based on a WIFI type short-range telecommunication system and a satellite location system. The short-range telecommunication system is used to locate the terminal accurately within the building in which it is situated. The method uses a cartographic representation of the buildings in order to deduce from the position of the terminal a set of satellites that could be received by the terminal. The satellites are then acquired to synchronize the terminal to the satellite system. That synchronization is then used when the terminal leaves the building to acquire as quickly as possible the set of satellites of the satellite navigation constellation.

Claims

1. A method of accelerated acquisition of positioning satellite signals from a satellite location system for a mobile terminal moving from the interior to the exterior of a building, the mobile terminal coupling a transceiver capable of exchanging signals of a local range telecommunication system to a transceiver capable of exchanging positioning satellite signals of the satellite location system,

which method includes the following steps:

a step of determination of the approximate position of the terminal by measuring a parameter of a signal coming from at least one access point of the local range telecommunication system immediately the terminal searching for location information detects such an access point,

a step of determination of the orientations of the various satellites of the satellite location system capable of being perceived from the determined position of the terminal,

a step of determination of the probability of acquisition of signals coming from the various satellites, as a function of the azimuth and the elevation of each of said satellites perceived and a radio wave attenuation coefficient for the determined position of the terminal known to a system of graphical representation of buildings and of representation of their internal architecture, the latter system being adapted to associate with each position in a building a distribution of probability of acquisition of a satellite signal coming from a given direction,

a step of searching for satellite signals coming from said satellites for which the probability of reception exceeds a certain threshold,

a step of synchronization of the terminal to the satellite signal or signals acquired.

2. A method according to claim 1, wherein, before the step of determination of the probability of acquisition of signals coming from the various satellites, there is a step of transmission by the cartographic representation system to the terminal of a local map representing the building and its interior architecture in which said terminal is situated.

3. A hybrid location system for accelerated acquisition of positioning satellite signals for a mobile terminal moving from the interior toward the exterior of a building, the hybrid location system including:

a local range telecommunication system,

a satellite location system,

the mobile terminal coupling a transceiver capable of exchanging local telecommunication signals to a transceiver capable of exchanging positioning satellite signals,

which system further includes;

a system of cartographic representation of buildings and of representation of their interior architecture adapted to associate with each position in a building a distribution of probability of acquisition of a satellite signal coming from a given direction,

means for determining the position of the terminal by measurement of a parameter of a signal coming from at least one access point of the local range telecommunication system immediately the terminal searching for location information detects such an access point,

means for determining the probability of acquisition of signals coming from the various satellites as a function of the azimuth and the elevation of the various satellites of the satellite location system capable of being perceived from the determined position of the terminal and as a function of a radio wave attenuation coefficient for the determined position of the terminal known to the cartographic representation system,

means for searching for satellite signals coming from said satellites for which the probability of reception exceeds a certain threshold,

means for synchronization of the terminal to the satellite signal or signals acquired.

4. A system according to claim 3, wherein the system of cartographic representation of buildings and of representation of their interior architecture is integrated into a location server using an Assisted-GPS or Assisted-GNSS location technique.