Method and apparatus for locating a remote unit within a communication system

• US 6,160,511 A
• Filed: 09/30/1999
• Issued: 12/12/2000
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Pfeil, Jeff L., Tapia, Javier J.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US09/409,552
• Time in Patent Office: 439 Days
• Field of Search: 342/457, 455/456
• US Class Current: 342/457
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A base station (101) calculates a location of a remote unit (113) using a first location technique. The first location technique is a single-site estimation of a PN offset for the remote unit (PN_primary.sbsb.--_site). PN_primary.sbsb.--_site is then forwarded by the base station (101), along with its base station identification, to locating equipment (107). Equipment (107) then passes a second location request to the serving base station (101) and those base stations neighboring the serving base station (neighbor base stations). PN_primary.sbsb.--_site is sent with the second location request, along with an identity of the base station that made the first location estimate. The neighboring base stations then calculate a "search window" for each base station to search when locating the remote unit (113). The search range is based on the first location, and the identity of the base station that made the first location estimate.

Claims

1. A method for locating a remote unit within a communication system, the method comprising the steps of:

receiving at a base station, a location request to perform a location of the remote unit, wherein the location request comprises a first location of the remote unit; and

performing a location of the remote unit within a search window bounded by an upper and a lower time offset, wherein the step of performing is based on the location request, the first location of the remote unit, and a distance from the base station to a second base station, wherein the second base station performed the first location of the remote unit.

2. The method of claim 1 wherein the step of receiving, at the base station, the location request comprises the step of receiving, at the base station, a request to participate in a multi-site location of the remote unit.

3. The method of claim 1 wherein the step of receiving the request to participate in the multi-site location of the remote unit comprises the step of receiving a request to perform a multi-site Time Difference Of Arrival (TDOA) location of the remote unit.

4. The method of claim 1 further comprising the step of searching for the remote unit with a receiver utilizing the search window, wherein the search window is based on the first location of the remote unit, and the distance (PN_primary.sbsb.--_site) from the base station to the second base station.

5. The method of claim 4 wherein the step of searching for the remote unit comprises the step of searching for the remote unit with the receiver utilizing a search window, wherein the search window is based on the first location of the remote unit, and the distance from the base station to the second base station, a bore site azimuth (.o slashed.)of the second base station, a sector size (β

) of the second base station, and a sector within the second base station'"'"'s coverage area.

6. The method of claim 5 wherein the step of searching for the remote unit with the receiver utilizing a search window comprises the step of searching for the remote unit using a search window having a maximum (PN_final) and minimum (PN_initial) search window wherein

7. The method of claim 3 wherein the step of searching for the remote unit with the receiver utilizing a search window comprises the step of searching for the remote unit using a search window having a maximum (PN_initial) and minimum (PN_initial) search window wherein

8. The method of claim 4 wherein the step of searching for the remote unit with the receiver utilizing a search window comprises the step of searching for the remote unit using a search window having a maximum (PN_initial) and minimum (PN_initial) search window wherein

9. A method for locating a remote unit within a communication system, the method comprising the steps of:

receiving at a base station, a location request to perform a location of the remote unit, wherein the location request comprises a first location of the remote unit;

instructing a receiver to search for the remote unit within a window bounded by an upper (PN_initial) and a lower (PN_final) PN offset, wherein PN_initial and PN_final are based on the first location of the remote unit (PN_primary.sbsb.--_site) and a distance that the base station is from a second base station, wherein the second base station performed the first location of the remote unit; and

performing a location of the remote unit based on the location request, the first location of the remote unit, and a distance from the base station to a second base station.

10. The method of claim 9 wherein the step of receiving, at the base station, the location request comprises the step of receiving, at the base station, a request to participate in a multi-site location of the remote unit.

11. The method of claim 10 wherein the step of receiving the request to participate in the multi-site location of the remote unit comprises the step of receiving a request to perform a multi-site Time Difference Of Arrival (TDOA) location of the remote unit.

12. The method of claim 9 wherein the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final comprises the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final wherein PN_initial and PN_final are further based on a bore site azimuth of the second base station (.o slashed.), a sector size (β

) of the second base station, and a sector within the second base station'"'"'s coverage area.

13. The method of claim 12 wherein the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final comprises the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final wherein

14. The method of claim 9 wherein the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final comprises the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final wherein

15. The method of claim 9 wherein the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final comprises the step of instructing the receiver to search for the remote unit within the window bounded by PN_initial and PN_final wherein

16. A base station for locating a remote unit within a communication system, the base station comprises a logic unit having a location request and a first location as an input and outputting a search window for utilization by a receiver, wherein the search window is based on the location request, the first location of the remote unit, and a distance from the base station to a second base station, wherein the second base station performed the first location of the remote unit.

17. The base station of claim 16 wherein the search window is bounded by PN_initial and PN_final wherein PN_initial and PN_final are based on a bore site azimuth of the second base station (.o slashed.), a sector size (β

) of the second base station, and a sector within the second base station'"'"'s coverage area.

18. The base station of claim 17 wherein

19. The base station of claim 17 wherein

20. The base station of claim 17 wherein