METHOD OF OPTIMIZATION OF PROCESSING OF LOCATION DATA IN THE PRESENCE OF A PLURALITY OF SATELLITE POSITIONING CONSTELLATIONS

• US 20070236387A1
• Filed: 12/28/2006
• Published: 10/11/2007
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Monnerat, Michel
• Granted Patent: US 7,646,338 B2
• Time in Patent Office: Days
• US Class Current: 342/356
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS

Abstract

The present invention concerns a method of optimization of processing of signals from satellite positioning systems in the case where at least two satellite systems cohabit and are utilized to obtain the position of a receiver. One of the systems is given preference on the basis of a criterion of performance and the satellites of the other systems are eliminated that are situated at an azimuth/elevation angle difference less than a threshold relative to the satellites of the preferred system.

Claims

1. Method of management of positioning satellite signals (15a, 15b, 15c) coming from a first constellation of satellites (GPS, 26) and a second constellation of satellites (Galileo, 25) of a first and a second satellite location system for locating a mobile terminal (27) of a cellular communication network capable of exchanging satellite signals with the first and second satellite location systems (GPS, Assisted GPS, Galileo, Assisted Galileo), characterized in that said method comprises the following steps:

a step (16) of determination of an approximate pre-location of the terminal,

a step (17) of estimation of the position of the satellites of said first and second constellations,

a step of resolution of the list of satellites visible from the terminal as a function of the approximate pre-location of the terminal that has been determined and from the estimated position of the satellites,

a step (18) of calculation of the elevation and the azimuth of each satellite from the list of satellites visible from the terminal as a function of the approximate position of the terminal,

a step (21, 22, 23, 24) of sorting of the satellites from the list of visible satellites by;

giving preference to one of said satellite constellations on the basis of a performance criterion,

excluding (24) from the list of visible satellites all of the satellites belonging to the constellations other than the preferred constellation and the position whereof in azimuth and in elevation from the point of view of the terminal is confined within a predetermined angular range relative to one of the satellites of the preferred constellation.

2. Method according to claim 1, characterized in that the qualification [20] of the constellation as the preferred constellation is effected by the construction [19] of N groups of satellites belonging to the list of satellites visible from the terminal, where N corresponds to the number of satellite positioning constellations used in the calculation of the position of the user, a group of satellites being defined in that all the satellites of the same group belong to the same constellation, the constellation assuming the preferred quality with an index 1 being considered in that the physical characteristics of the signals coming from the latter are more favorable to positioning performance.

3. Method according to claim 2, characterized in that the step of sorting of the satellites (21, 22, 23, 24), for each satellite Sat_i of the constellation 2 to N, utilizes the following phases:

calculation (22) of the angular difference between the azimuth of the satellite Sat_i and the azimuth of all of the satellites of the constellation 1,

calculation (23) of the angular difference between the elevation of the satellite Sat_i and the elevation of all of the satellites of the constellation 1, elimination (24) of the satellite Sat_i from the list of satellites visible from the position of the terminal if the elevation and azimuth angular differences are less than a respective given value (A0, E0).

4. Method according to claim 1, characterized in that the step (16) of determination of an approximate pre-location of the terminal utilizes either the result of a triangulation within the cellular communication network to deduce the pre-location therefrom, or location information coming from the position of a base station of the cell in which the terminal is situated.

5. Method according to claim 1, characterized in that the step (16) of determination of an approximate pre-location of the terminal utilizes an earlier pre-location of the terminal.

6. Method according to claim 1, characterized in that it comprises a step of processing by the terminal of satellite signals from each satellite from the list of visible satellites, minus those that have been excluded.

7. System for management of positioning satellite signals (15a, 15b, 15c) coming from a first constellation of satellites (GPS, 26) and a second constellation of satellites (Galileo, 25) of a first and a second satellite location system for locating a mobile terminal (27) of a cellular communication network capable of exchanging satellite signals with the first and second satellite location systems (GPS, Assisted GPS, Galileo, Assisted Galileo), characterized in that said management system comprises:

means (28) for determination of an approximate pre-location of the terminal, means (29) for estimation of the position of the satellites of said first and second constellations,

means (30) for resolution of the list of satellites visible from the terminal as a function of the approximate pre-location of the terminal that has been determined and from the estimated position of the satellites,

means (31) for calculation of the elevation and the azimuth of each satellite from the list of satellites visible from the terminal as a function of the approximate pre-location of the terminal,

means (32) for sorting of the satellites from the list of visible satellites by;

giving preference to one of said satellite constellations on the basis of a performance criterion,

excluding from the list of visible satellites all of the satellites belonging to the constellations other than the preferred constellation and the position whereof in azimuth and in elevation from the point of view of the terminal is confined within a predetermined angular range relative to one of the satellites of the preferred constellation.

means (9, 10) for transmission to the terminal (27) of assistance data relating to the list of satellites visible from the terminal, minus the excluded satellites.

8. System according to claim 7, characterized in that the system comprises an assistance data server (34) that integrates said means (28) for determination of an approximate pre-location of the terminal, said means (29) for estimation of the position of the satellites of said first and second constellations, said means (30) for resolution of the list of satellites visible from the terminal as a function of the approximate pre-location of the terminal that has been determined and the estimated position of the satellites, said means (31) for calculation of the elevation and the azimuth of each satellite from the list of satellites visible from the terminal as a function of the approximate pre-location of the terminal, said means (32) for sorting the satellites from the list of visible satellites, and means (35) for transmission to the terminal of assistance data relating to the list of satellites visible from the terminal, minus the excluded satellites.