Estimating the location of a mobile unit based on the elimination of improbable locations

• US 6,944,465 B2
• Filed: 11/18/2002
• Issued: 09/13/2005
• Est. Priority Date: 09/22/1998
• Status: Expired due to Term

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: Polaris Wireless Incorporated
• Inventors: Martin, Robert Lewis, Spain, David Stevenson, Perez-Breva, Luis
• Primary Examiner(s): Trinh, Sonny
• Assistant Examiner(s): PHAN, HUY Q
• Application Number:
  US10/299,398
• Publication Number:
  US 20030064735A1
• Time in Patent Office: 1,030 Days
• Field of Search: 4554561-4566, 455/229, 455/421, 340/984, 340/941, 34235701-35712, 342/404.2, 342/456.3, 342/422.1
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/02529 not involving signal parameters, i.e. only involving identifiers
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for determining the location of a mobile unit (mobile unit) in a wireless communication system is disclosed. The illustrative embodiment provides a computationally-efficient technique for reducing the number of possible positions that have to be analyzed. In particular, the illustrative embodiment eliminates possible positions for the mobile unit from consideration by considering which signals the mobile unit can—and cannot—receive and the knowledge of where those signals can and cannot be received.

Claims

1. A method for estimating the location of a mobile unit from a plurality of possible positions, said method comprising:

receiving an indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter.

2. The method of claim 1 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is inferred because said mobile unit failed to indicate that said mobile unit did receive said first signal.

3. The method of claim 1 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is explicit.

4. The method of claim 1 further comprising:

receiving an indication from said mobile unit that said mobile unit does not receive a second signal from a second transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did not receive said second signal from said second transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter or said second signal from said second transmitter.

5. The method of claim 1 further comprising:

receiving an indication from said mobile unit that said mobile unit did receive a second signal from a second transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did receive said second signal from said second transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter but did receive said second signal from said second transmitter.

9. The method of claim 4 further comprising:

receiving an indication from said mobile unit that said mobile unit does not receive a second signal from a second transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did not receive said second signal from said second transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter or said second signal from said second transmitter.

10. The method of claim 4 further comprising:

receiving an indication from said mobile unit that said mobile unit did receive a second signal from a second transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did receive said second signal from said second transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter but did receive said second signal from said second transmitter.

6. A method for estimating the location of a mobile unit, said method comprising:

receiving the cell ID of the cell site servicing said mobile unit;

generating a plurality of possible positions in which said mobile unit might be based on said cell ID;

receiving an indication from said mobile unit that said mobile unit did not receive a first signal from a first transmitter;

eliminating some of said plurality of possible positions from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions not eliminated from consideration based on the fact that said mobile unit did not receive said first signal from said first transmitter.

7. The method of claim 6 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is inferred because said mobile unit failed to indicate that said mobile unit did receive said first signal.

8. The method of claim 6 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is explicit.

11. A method comprising:

receiving an indication from a mobile unit of a plurality of signals that said mobile unit can receive and a plurality of signals that said mobile unit cannot receive;

generating a plurality of possible positions based on said plurality of signals that said mobile unit can receive and on said plurality of signals that said mobile unit cannot receive; and

choosing as an estimate of said position of said mobile unit one of said plurality of possible positions by comparing the fingerprint associated with each of said plurality of possible positions against a fingerprint received from said mobile unit.

12. The method of claim 11 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is inferred because said mobile unit failed to indicate that said mobile unit did receive said first signal.

13. The method of claim 11 wherein said indication from said mobile unit that said mobile unit does not receive a first signal from a first transmitter is explicit.

14. A method for estimating a location of a mobile unit, said method comprising:

directing said mobile unit to report a signal strength value for the strongest of a first plurality of signals;

receiving a signal strength value from said mobile unit for a second plurality of signals, wherein said second plurality of signals is a non-empty subset of said first plurality of signals; and

eliminating from consideration as said location of said mobile unit any location at which any of said second plurality of signals is known to be less strong than any of said first plurality of signals not reported.

15. The method of claim 14 wherein a range of uncertainty is considered when determining when any of said second plurality of signals is compared with any of said first plurality of signals.