Method and apparatus to select an optimum site and/or sector to provide geo-location data

• US 20080293435A1
• Filed: 05/21/2007
• Published: 11/27/2008
• Est. Priority Date: 05/21/2007
• Status: Active Grant

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Carlson, John, Maher, George, Kalenahalli, Ananth
• Granted Patent: US 7,933,610 B2
• Time in Patent Office: Days
• US Class Current: 455/456.2
• CPC Class Codes: G01S 5/0269 Inferred or constrained positioning, e.g. employing knowledge of the physical or electromagnetic environment, state of motion or other contextual information to infer or constrain a position
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system and method selects secondary base stations to task that provide geo-location information used to geo-locate a mobile station. A network overlay location system may be co-located at base station sites of a wireless communications network. The location measurement units of the network overlay system provide location information of the mobile station, which may be determined via one or more geo-location techniques, for example: time of arrival (TOA), time difference of arrival (TDOA), uplink time difference of arrival (UTDOA), angle of arrival (AOA), signal power, radio fingerprinting etc. Selecting secondary base stations to task using various selection criteria may provide optimum results when geo-locating a mobile station.

Claims

1. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:

receiving a location request;

determining a serving sector of a serving site;

determining a reference position within the geographical area of the serving sector;

selecting at least one secondary site to provide location information of the mobile station, the secondary site being selected based on its location with respect to the reference position;

obtaining the location information from at least one measurement unit located within the at least one secondary site; and

estimating the location of the mobile station based on the obtained location information.

2. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:

selecting a reference position within a communication coverage area of a of a first site;

selecting at least one secondary site according to a function of the reference position;

selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and

tasking the at least one secondary sector to obtain location information of the mobile station.

3. The method of claim 2, wherein the reference position is the location of the first site.

4. The method of claim 2, wherein the reference position is determined according to a function of the heading position of the mobile station'"'"'s serving sector, and is located within the geographical area of the serving sector of the first site.

5. The method of claim 2, wherein the reference position is determined to be a predetermined distance from the first site and in a serving sector of the first site, the predetermined distance based on a percentage of an average inter-site distance between two or more sites.

6. The method of claim 5, wherein the percentage of the average inter-site distance is approximately twenty percent.

7. The method of claim 2, wherein said method further comprises:

determining a distance range to available secondary sites from the reference position; and

omitting those secondary sites whose distance from the reference position exceeds a distance threshold.

8. The method of claim 2, wherein said method further comprises:

determining the bearing angle from available secondary sites to the reference position; and

omitting those secondary sites that do not include the reference position in any sectorized antenna beams.

9. The method of claim 2, wherein said method further comprises:

determining which secondary site is closest to the reference position; and

flagging that site so it is no longer considered an available candidate site.

10. The method of claim 2, wherein said method further comprises:

calculating a cost function to determine which secondary site has the minimum total cost, and flagging that site as longer considered an available candidate site,

wherein the cost function is;

COST=W(D<sub>MS—

BS</sub>^F)+|B_L−

B<sub>MS—

BS|;</sub>

where W is a weighting factor that controls the relative cost between distance and bearing costs, D<sub>MS—

BS</sub> is the distance from the mobile station reference position to the base station in kilometers, F is an exponent representing the distance cost penalty for a distance inside a cutoff radius measured from the MS reference position, B_L is a look direction bearing angle, and B<sub>MS—

BS</sub> is a bearing angle measured from the mobile station to the base station.

11. The method of claim 2, wherein said method further comprises:

calculating a cost function to determine which secondary site has the minimum total cost, and flagging that site as longer considered an available candidate site,

wherein the cost function is;

COST=(W*D<sub>MS—

Bs</sub>+C)+|B_L−

B<sub>MS—

BS</sub>|;

where W is a weighting factor that controls the relative cost between distance and bearin angle costs, D<sub>MS—

BS</sub> is the distance from the mobile station reference position to the base station in kilometers, C is a constant term equal to the distance cost evaluated at the distance cutoff radius, B_L is a look direction bearing angle, and B<sub>MS—

BS</sub> is a bearing angle measured from the mobile station to the base station.

12. The method of claim 2, wherein said method further comprises:

calculating the estimated mobile station position using an AOA algorithm.

13. The method of claim 2, wherein said method further comprises:

calculating the estimated mobile station position using a UTDOA algorithm.

14. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:

selecting a reference position within a communication coverage area of a first site;

selecting at least one secondary site according to a function of the reference position;

selecting at least one sector of the at least one selected secondary site to task based on the reference position; and

tasking the at least one sector to obtain location information of the mobile station.

15. A mobile station geo-location system having a plurality of base station sites co-located with location measurement units (LMUs), the system comprising:

a first site designated as a serving site in communication with the mobile station;

at least one secondary site selected to provide location information of the mobile station, the at least one secondary site selected from a group of at least two secondary sites, and where the at least one selected secondary site produces at least one preferred parameter that the least one non-selected secondary site can not produce.

16. The system of claim 15, wherein the preferred parameter is a shorter distance between the first site and the at least on secondary site.

17. The system of claim 15, wherein the preferred parameter is a shorter distance between a reference position, located within the communication coverage area of the first site, and the at least one secondary site.

18. The system of claim 15, wherein the preferred parameter is a predetermined distance range radius and the at least one selected site is inside the distance range radius and the at least one non-selected site is outside the distance range radius.

19. A method of geo-locating a MS in a geographic area serviced by a plurality of BS sites co-located with location measurement units (LMUs), and at least one geo-location control system (GCS) with a record of the mobile station'"'"'s current serving BS site and respective current serving sector, the improvement comprising determining a reference position location of the mobile station within the current serving sector and based on the reference position, tasking a secondary base station site and/or sector of the secondary base station to provide location information of the mobile station.

20. A method of geo-locating a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:

determining the locations of secondary base station sites with respect to a serving base station site location;

selecting a mobile station reference position based on the type of location arrangement of the secondary sites;

selecting at least one secondary site according to a function of the reference position;

selecting at least one secondary sector of the at least one selected secondary site to task based on a function of the reference position; and

tasking the at least one secondary sector to obtain location information of the mobile station.

21. A method of selecting one or more secondary base station sites to geo-locate a mobile station in a geographic area serviced by a plurality of base station sites co-located with location measurement units (LMUs), the method comprising:

selecting a mobile station reference position based on the location of the serving base station site;

computing a distance range to one or more secondary sites;

omitting the secondary sites outside the distance range as potential secondary site candidates;

computing the bearing angle from at least one secondary site to the reference position;

determining which secondary sites do not have at least one sector beam that covers the reference position;

omitting the secondary sites that do not have at least one sector beam that covers the reference position as potential secondary site candidates; and

flagging the secondary site that is closest to the mobile station reference position as a selected secondary site.