Position determination using multiple base station signals

• US 5,907,809 A
• Filed: 09/20/1996
• Issued: 05/25/1999
• Est. Priority Date: 01/11/1994
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Molnar, Barbara, Molnar, Karl, Ramesh, Rajaram, Hassan, Amer Aref
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US08/710,761
• Time in Patent Office: 977 Days
• Field of Search: 455/405, 455/414, 455/422, 455/436, 455/440, 455/445, 455/456, 455/457, 342/357
• US Class Current: 455/456.2
• CPC Class Codes: G01S 3/146 by comparing linear polarisation components
• CPC Class Codes: G01S 3/28 using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: H04B 7/18545 Arrangements for managing station mobility, i.e. for station registration or localisation
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service
• CPC Class Codes: H04L 1/0069 Puncturing patterns
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2001/0098 Unequal error protection
• CPC Class Codes: H04L 25/03331 Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04W 16/28 : using beam steering
• CPC Class Codes: H04W 64/00 : Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Exemplary embodiments of the present invention describe terminal position location methods and systems. Relative powers of nearby spot beams which are generated by array antennas are determined. For example, powers from six neighboring spot beams relative to a center spot beam within which a mobile station is currently operating, can be measured relative to the power of the center spot beam. Using information from these measurements, the mobile stations position can be determined using, for example, an exponential model of the spot beam pattern.

Claims

1. A method for locating a terminal in a radiocommunication system using an array to illuminate areas with spot beams, comprising the steps of:

(a) measuring, at a first base station, a received power associated with each of a plurality of said spot beams;

(b) determining relative powers associated with said received power by comparing said relative powers with a reference power; and

(c) calculating a first bearing of said terminal relating to said first base station using said relative powers and a model of spot beam shape;

(d) repeating steps (a)-(c) for signals received by a second base station from said terminal to determine a second bearing of said terminal relative to said second base station; and

(e) locating said terminal by using said first and second bearings to triangulate said terminal'"'"'s position.

2. The method of claim 1, wherein said model is an exponential model.

3. The method of claim 1, wherein said first and second base stations are unsynchronized.

4. The method of claim 1, wherein said first and second base stations are synchronized.

5. The method of claim 4, further comprising the step of:

using time of arrival information associated with signals measured in step (a) to improve a position indication obtained from step (e).

6. The method of claim 1, further comprising the steps of:

(f) transmitting a locator signal including a first field having a known value with good correlation properties and a second field having a value indicating a time of transmission of said locator signal to said terminal;

(g) correlating, at said terminal, said locator signal with said known value to identify a time of receipt associated with a peak correlation value;

(h) determining a propagation delay using said value in said second field and said time of receipt; and

(i) locating said terminal using said propagation delay in addition to using said first and second bearings in step (e).

7. The method of claim 6, wherein said step of transmitting occurs during setup of a connection between said terminal and a radiocommunication system.

8. The method of claim 6, wherein said step of transmitting occurs during a wakeup period of said terminal while said terminal listens for paging messages.

9. A radiocominunication system including a mobile station and at least two base stations comprising:

a first antenna array associated with a first one of said at least two base stations for providing spot beam radiocommunication coverage of a first area using a first plurality of spot beams;

a second antenna array associated with a second one of said at least two base stations for providing spot beam radiocommunication coverage of a second area using a second plurality of spot beams, said second area at least partially overlapping said first area;

means for measuring, at said first base station, a received power from said mobile station associated with each of said first plurality of said spot beams;

means for measuring, at said second base station, a received power from said mobile station associated with each of said second plurality of said spot beams;

means for determining, based on said measurements at said first base station, a first bearing of said mobile station relative to said first base station;

means for determining, based on said measurements at said second base station, a second bearing of said mobile station relative to said second base station; and

means for locating said mobile station using said first and second bearings;

wherein said means for determining said first bearing uses a model of beam shape in addition to said measurements at said first base station.

10. The radiocommunication system of claim 9, wherein said model of beam shape is an exponential model.

11. The radiocommunication system of claim 9, wherein said first and second base station are unsynchronized.

12. The radiocommunication system of claim 9, wherein said first and second base station are synchronized.

13. The radiocommunication system of claim 12, wherein said means for locating also uses time of arrival information to locate said mobile station.