Enhanced determination of position-dependent signal characteristics of a wireless transmitter

• US 6,366,241 B2
• Filed: 03/22/2001
• Issued: 04/02/2002
• Est. Priority Date: 06/26/2000
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Pack, Kenneth D., Maloney, John E.
• Primary Examiner(s): Phan, Dao
• Application Number:
  US09/815,408
• Publication Number:
  US 20020011952A1
• Time in Patent Office: 376 Days
• Field of Search: 342/442, 342/444, 342/445, 342/450, 342/457
• US Class Current: 342/442
• CPC Class Codes: G01S 3/48 the waves arriving at the antennas being continuous or intermittent and the phase difference of signals derived therefrom being measured

Abstract

A method and system for determining with enhanced accuracy a line of bearing and related signal characteristics of a mobile wireless transceiver in a cellular-telephone communications system is presented. Three or more conventionally configured antenna elements are used to provide a high resolution line of bearing estimate through disambiguation of positional parameters associated with inter-element signal characteristics derived from signal products. The high resolution line of bearing estimate can then be used to determine the location of the transmitter.

Claims

1. A method for measuring position-dependent characteristics of mobile radio signals from a mobile transmitter, the method comprising the steps of

receiving the transmitted signals at an antenna configuration having multiple phase-synchronized receiving elements;

performing disambiguation processing for the extraction of position dependent characteristics of the signals; and

evaluating the characteristic parameters indicative of the transmitter'"'"'s position.

2. The method of claim 1, wherein said antenna configuration has three or more elements.

3. The method of claim 2, wherein said antenna elements comprise at least one pair of elements whose inter-element separation is a large quantity of half wavelengths of the signals.

4. The method of claim 2, wherein said antenna elements comprise at least two pairs of elements whose inter-element separations differ by a small quantity of half wavelengths of the signals.

5. The method of claim 1, wherein said disambiguation processing includes the extraction of signal characteristics having reduced ambiguity for resolving the selection of the accurate positional interpretation of extracted ambiguous characteristics.

6. The method of claim 1, wherein said disambiguation processing includes formation of differences of inter-element signal phase differences.

7. The method of claim 1, wherein said disambiguation processing includes formation of higher-order signal products.

8. The method of claim 1, wherein said evaluated characteristic parameters indicative of the transmitter'"'"'s position include angle of arrival.

9. The method of claim 1, wherein said evaluated characteristic parameters directly quantify the transmitter'"'"'s position.

10. An apparatus for measuring position-dependent characteristics of mobile radio communications signals from a mobile transmitter, comprising:

an antenna configuration having multiple elements for receiving the transmitted signals;

phase-synchronized elemental signal receivers for extracting the signals to be processed;

a signal processing unit that performs disambiguation processing for the extraction of position-dependent characteristics of the signals; and

a processing unit that evaluates the characteristic parameters indicative of the transmitter'"'"'s position.

11. An apparatus as in claim 10, wherein said antenna configuration has three or more elements.

12. An apparatus as in claim 11, wherein said antenna elements comprise at least one pair of elements whose inter-element separation is a large quantity of half wavelengths of the signals.

13. An apparatus as in claim 11, wherein said antenna elements comprise at least two pairs of elements whose inter-element separations differ by a small quantity of half wavelengths of the signals.

14. An apparatus as in claim 10, wherein said disambiguation processing includes the extraction of signal characteristics having reduced ambiguity for resolving the selection of the accurate positional interpretation of extracted ambiguous characteristics.

15. An apparatus as in claim 10, wherein said disambiguation processing includes formation of differences of inter-element signal phase differences.

16. An apparatus as in claim 10, wherein said disambiguation processing includes formation of higher-order signal products.

17. An apparatus as in claim 10, wherein said evaluated characteristic parameters indicative of the transmitter'"'"'s position include angle of arrival.

18. An apparatus as in claim 10, wherein said evaluated characteristic parameters directly quantify the transmitter'"'"'s position.

19. A method for measuring the angle of arrival (AOA) of a radio signal from a mobile transmitter, the method comprising:

detecting the radio signal at an antenna configuration having multiple antenna elements separated from each other by a known distance, wherein the distance between elements is larger than one-half of the received signal'"'"'s wavelength, whereby multiple angles of arrival can generate the same relative phase response;

determining an unambiguous phase difference representing the difference in phase of the signal as detected at the respective antenna elements; and

using the unambiguous phase difference to determine the angle of arrival of the received signal.

20. The method of claim 19, wherein the unambiguous phase difference is determined by disambiguation processing.

21. The method of claim 20, wherein said disambiguation processing includes correcting or reducing phase ambiguity in the received signal.

22. The method of claim 21, wherein said disambiguation processing includes formation of differences of inter-element signal phase differences.

23. The method of claim 21, wherein said disambiguation processing includes formation of higher-order signal products.

24. The method of claim 19, wherein the multiple receiving elements are phase-synchronized.

25. The method of claim 19, wherein said antenna elements comprise at least one pair of elements whose inter-element separation is a large quantity of half wavelengths of the received signal.

26. The method of claim 19, wherein said antenna elements comprise at least two pairs of elements whose inter-element separations differ by a small quantity of half wavelengths of the received signal.

27. The method of claim 19, wherein said antenna configuration has three or more elements.