Estimating the location of a wireless terminal based on calibrated signal-strength measurements

• US 8,068,802 B2
• Filed: 09/08/2010
• Issued: 11/29/2011
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: Polaris Wireless Incorporated
• Inventors: Spain, David Stevenson Jr., Feuerstein, Martin, Bhattacharya, Tarun Kumar
• Primary Examiner(s): Dao; Minh D
• Application Number:
  US12/877,774
• Publication Number:
  US 20100329144A1
• Time in Patent Office: 447 Days
• Field of Search: 455/231, 455/67.11, 455/67.13, 455/115.1, 455/456, 455/67.14, 455/115.3, 455/456.1, 455/63.1
• US Class Current: 455/231
• CPC Class Codes: G01S 5/02527 Detecting or resolving anomalies in the radio frequency fingerprints of the radio-map
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A process and machine for estimating the location of a wireless terminal is disclosed. The illustrative embodiment of the present invention is based on the observation that the signal strength of a signal from a transmitter is different at some locations, and, therefore, the location of a wireless terminal can be estimated by comparing the signal strength it currently observes against a map or database that correlates locations to signal strengths. In accordance with a first example, if a particular radio station is known to be received well at a first location and poorly at a second location, and a given wireless terminal at an unknown location is receiving the radio station poorly, it is more likely that the wireless terminal is at the second location than it is at the first location.

Claims

1. A process comprising:

receiving a first reported signal-strength measurement, R(1,n), from a wireless terminal; and

generating a first calibrated signal-strength measurement, S(1,n), based on;

(i) the first reported signal-strength measurement, R(1,n), and (ii) an identifying characteristic, C, of the wireless terminal;

wherein the first reported signal strength is for a first signal received by the wireless terminal; and

wherein the identifying characteristic, C, identifies the wireless terminal in comparison to another wireless terminal capable of receiving the first signal.

2. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal is the unique identity of the wireless terminal.

3. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal is the subscriber identity associated with the wireless terminal.

4. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal is the model of the wireless terminal.

5. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal comprises a feature of the radio-frequency circuitry of the wireless terminal.

6. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal is at least one component of the wireless terminal.

7. The process of claim 1 wherein the identifying characteristic, C, of the wireless terminal is the make of the wireless terminal.

8. The process of claim 1 further comprising receiving the identifying characteristic, C, of the wireless terminal from the wireless terminal.

9. The process of claim 1 further comprising estimating the location of the wireless terminal based on the first calibrated signal-strength measurement, S(1,n).

10. A machine comprising:

a receiver for receiving a first reported signal-strength measurement, R(1,n), from a wireless terminal; and

a processor for generating a first calibrated signal-strength measurement, S(1,n), based on;

(i) the first reported signal-strength measurement, R(1,n), and (ii) an identifying characteristic, C, of the wireless terminal;

wherein the first reported signal strength is for a first signal received by the wireless terminal; and

wherein the identifying characteristic, C, identifies the wireless terminal in comparison to another wireless terminal capable of receiving the first signal.

11. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal is the unique identity of the wireless terminal.

12. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal is the subscriber identity associated with the wireless terminal.

13. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal is the model of the wireless terminal.

14. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal comprises a feature of the radio-frequency circuitry of the wireless terminal.

15. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal is at least one component of the wireless terminal.

16. The machine of claim 10 wherein the identifying characteristic, C, of the wireless terminal is the make of the wireless terminal.

17. The machine of claim 10 wherein the receiver is also for receiving the identifying characteristic, C, of the wireless terminal from the wireless terminal.

18. The machine of claim 10 wherein the processor is also for estimating the location of the wireless terminal based on the first calibrated signal-strength measurement, S(1,n).

19. A process comprising:

generating a first calibrated signal-strength measurement, S(1,n), based on (i) a first reported signal-strength measurement, R(1,n), as made by a wireless terminal and (ii) an identifying characteristic, C, of the wireless terminal; and

estimating the location of the wireless terminal based on the first calibrated signal-strength measurement, S(1,n);

wherein the first reported signal strength is for a first signal received by the wireless terminal; and

wherein the identifying characteristic, C, identifies the wireless terminal in comparison to another wireless terminal capable of receiving the first signal.

20. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is the unique identity of the wireless terminal.

21. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is the subscriber identity associated with the wireless terminal.

22. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is the model of the wireless terminal.

23. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal comprises a feature of the radio-frequency circuitry of the wireless terminal.

24. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is at least one component of the wireless terminal.

25. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is the make of the wireless terminal.

26. The process of claim 19 wherein the identifying characteristic, C, of the wireless terminal is provided by the wireless terminal.

27. A machine comprising:

a receiver for receiving a first reported signal-strength measurement, R(1,n), as made by a wireless terminal; and

a processor for;

generating a first calibrated signal-strength measurement, S(1,n), based on (i) the first reported signal-strength measurement, R(1,n), and (ii) a identifying characteristic, C, of the wireless terminal; and

estimating the location of the wireless terminal based on the first calibrated signal-strength measurement, S(1,n);

wherein the first reported signal strength is for a first signal received by the wireless terminal; and

wherein the identifying characteristic, C, identifies the wireless terminal in comparison to another wireless terminal capable of receiving the first signal.

28. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal is the unique identity of the wireless terminal.

29. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal is the subscriber identity associated with the wireless terminal.

30. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal is the model of the wireless terminal.

31. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal comprises a feature of the radio-frequency circuitry of the wireless terminal.

32. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal is at least one component of the wireless terminal.

33. The machine of claim 27 wherein the identifying characteristic, C, of the wireless terminal is the make of the wireless terminal.

34. The machine of claim 27 wherein the receiver is also for receiving the identifying characteristic, C, of the wireless terminal as reported by the wireless terminal.