System and method for A-GPS positioning of a mobile device

• US 7,847,728 B2
• Filed: 04/08/2008
• Issued: 12/07/2010
• Est. Priority Date: 12/07/2007
• Status: Expired due to Fees

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Harper, Neil, Tran, Khiem, Thomson, Martin
• Primary Examiner(s): Tarcza, Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/099,694
• Publication Number:
  US 20090146876A1
• Time in Patent Office: 973 Days
• Field of Search: 342/357.09, 342/357.12, 342/357.42
• US Class Current: 342/357.42
• 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 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/28 Satellite selection

Abstract

A system and method for estimating the position of a mobile device using information from a constellation of satellites. A first set of satellites of the constellation may be selected and then a second set of satellites of the constellation may be selected as a function of signals received from the first set of satellites. Data may be transmitted to the mobile device based on signals received from the second set of satellites, and a location of the device estimated based on the data. One embodiment may select the second set as a function of an intersection of coverage areas of ones of the first set of satellites. Another embodiment may select the second set as a function of one or more satellites that are not occluded by the Earth from one or more of the first set of satellites.

Claims

1. A method for determining the location of a wireless device comprising the steps of:

(a) determining a first set of satellites for a region in which the wireless device is located;

(b) transmitting first assistance data to said device, said first assistance data including first information from said first set of satellites;

(c) attempting to measure first signals transmitted from one or more satellites in said first set;

(d) determining a second set of satellites as a function of said first signals received from said first set of satellites;

(e) transmitting second assistance data to said device, said second assistance data including second information from said second set of satellites;

(f) attempting to measure second signals transmitted from one or more satellites in said second set; and

(g) estimating a location of the device from said second signals.

2. The method of claim 1 further comprising iteratively repeating steps (d) through (f) until said second set of satellites is equal to or greater than a predetermined threshold.

3. The method of claim 2 further comprising the step of combining measurements of said second signals from one or more iterations to meet said predetermined threshold.

4. The method of claim 1 wherein there is no intersection between the first set and second set of satellites.

5. The method of claim 1 wherein attempting to measure second signals further comprises ensuring that said device does not attempt to measure one or more satellites in said first set having a measured first signal.

6. The method of claim 1 further comprising the step of suppressing transmissions of ones of said second assistance data if said second assistance data was previously provided to said device.

7. The method of claim 1 wherein said second set is selected as a function of coverage areas of said first signals from ones of said first set of satellites.

8. The method of claim 1 wherein said second set is selected as a function of one or more satellites that are not occluded by the Earth from said first signals from ones of said first set of satellites.

9. The method of claim 1 wherein the estimated location of the device is a function of signals provided by a cellular network.

10. The method of claim 1 wherein the satellites are part of a Global Navigation Satellite System (“

GNSS”

).

11. The method of claim 10 wherein the GNSS is selected from the group consisting of:

Global Positioning System (“

GPS”

), Galileo, GLONASS, and Quasi-Zenith Satellite System (“

QZSS”

).

12. The method of claim 1 wherein the wireless device is selected from the group consisting of:

cellular device, text messaging device, computer, portable computer, vehicle locating device, vehicle security device, communication device, and wireless transceiver.

13. The method of claim 1 wherein said region is selected from the group consisting of:

a serving area of a base station serving said wireless device, an approximate area of a communications network, a city, a municipality, a county, a state, a country, a continent, and the Earth.

14. The method of claim 1 wherein said location is estimated as a function of a pseudo-measurement.

15. The method of claim 1 wherein determining a second set of satellites further comprises including more or less satellites in said second set as a function of satellite elevation.