Method for finding the location of a mobile terminal in a cellular radio system

• US 20060068809A1
• Filed: 09/29/2004
• Published: 03/30/2006
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Riley, Wyatt T., Wengler, Michael
• Granted Patent: US 7,702,338 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system, method and device are provided which determine the position of a mobile station in connection with consulting signal delay transmission data from an almanac for the purpose of identifying the nearest set of base stations. Thereafter, the position of the mobile station is determined using multilateration.

Claims

1. A system for determining the position of a mobile station comprising:

an almanac including signal delay transmission data information for a mapped area from a set of base stations to selected locations on said mapped area;

a comparator operable to compare almanac data for selected sets of base stations with measured signal delay data collected by said mobile station, said comparator being further operable to assign a probability score to each selected set of base stations corresponding to said measured signal delay data;

a tower set selector operable to select a set of base stations most indicative of signals to said mobile station based on said probability score; and

multilateration equipment operable to obtain a position fix for said mobile station based upon the base stations selected by said tower set selector.

2. A system for determining the position of a mobile station as recited in claim 1 wherein said system provides radio-channel access through a technique selected from the group of radio-channel access schemes consisting of CDMA, TDMA, FDMA and SDMA or a combination thereof.

3. A system for determining the position of a mobile station as recited in claim 1 wherein each set of base stations comprises three base stations.

4. A system for determining the position of a mobile station as recited in claim 1 wherein each set of base stations comprises two base stations.

5. A system as recited in claim 1 wherein said almanac signal delay transmission data information is generated based upon the known locations of BTS sites.

6. A system as recited in claim 1 wherein said almanac signal delay transmission data information results from measurements made in connection with a survey of signal data over an area.

7. A system as recited in claim 1 wherein said comparator is a communications network computer.

8. A system as recited in claim 1 wherein said selected sets of base stations are chosen on the basis of base station pilot signal strength.

9. A system as recited in claim 1 wherein said probability score is defined in terms of a standard deviation from a mean in connection with a Gaussian distribution.

10. A system as recited in claim 1 which further includes a database for storage of said probability scores.

11. A system as recited in claim 1 wherein said mobile station is a mobile communications device selected from the group consisting of a mobile phone, a personal digital assistant with wireless communications capability, a portable computer with wireless communications capability and a pager.

12. A method of determining the position of a mobile station comprising:

collecting signal delay data from a location in the vicinity of said mobile station;

comparing said collected signal delay data with selected almanac signal delay data from an almanac, said almanac signal delay data representing signal delay information pertaining to predetermined sets of base station sites;

assigning a probability score to said selected almanac signal delay data based on statistical correlation between said collected data and said selected almanac signal delay data;

selecting a predetermined set of base stations with a probability score indicative of greatest correlation to said collected data;

locating the position of said mobile station according to a technique of multilateration using transmitting base station data from said base stations with said probability score indicative of the greatest correlation to said collected data.

13. A method of determining the position of a mobile station as recited in claim 12 wherein said almanac data is generated based upon the known locations of BTS sites.

14. A method of determining the position of a mobile station as recited in claim 13 wherein said almanac data results from measurements in connection with a survey of signal data over an area.

15. A method of determining the position of a mobile station as recited in claim 13 wherein each predetermined set of base station sites comprises three base station sites.

16. A method of determining the position of a mobile station as recited in claim 12 wherein said predetermined sets of base stations are chosen on the basis of base station pilot signal strength.

17. A method as recited in claim 12 wherein said mobile station is a mobile communications device selected from the group consisting of a mobile phone, a personal digital assistant with wireless communications capability, a portable computer with wireless communications capability and a pager.

18. A mobile station comprising:

a display;

an antenna;

a radio frequency section for providing a communications link to a communications network through said antenna; and

a processor programmed for making signal delay calculations in connection with data received from said communications network and for providing a readout on said display.

19. A mobile station as recited in claim 18 wherein said mobile station is a mobile communications device selected from the group consisting of a mobile phone, a personal digital assistant with wireless communications capability, a portable computer with wireless communications capability and a pager.