Enhanced time-difference localization system

• US 6,119,013 A
• Filed: 02/16/1999
• Issued: 09/12/2000
• Est. Priority Date: 05/17/1996
• Status: Expired due to Term

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: KSI Inc. (Liberty Broadband Corp.)
• Inventors: Maloney, John E., Stevenson, James O., Hinkle, Charles J. Jr.
• Primary Examiner(s): LE, THANH C
• Application Number:
  US09/250,391
• Time in Patent Office: 574 Days
• Field of Search: 455/422, 455/456, 455/455, 455/457, 455/458, 455/560, 455/561, 455/FOR 101, 701/207, 342/457, 342/453
• US Class Current: 455/456.2
• CPC Class Codes: G01S 2205/006 for emergency situations
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system and method for locating a mobile transceiver relative to plural fixed sensor stations. The system includes plural sensor stations that receive a signal transmitted by the mobile transceiver. A probable position of the mobile transceiver is determined based on a time of arrival of the signal and an angle of arrival of the signal received at the plural sensor stations.

Claims

1. An apparatus for locating a mobile radio communications transceiver in an operating environment served by a wireless communications system, comprising:

two sensor stations of known location that receive a radio signal from the mobile transceiver, each sensor station having an inter-site synchronization mechanism for common time standard maintenance, and each sensor station further having a corresponding signal characterization processing unit that determines, from the radio signal, time of signal arrival information;

a source of collateral information related to a location of the mobile transceiver, wherein the collateral information comprises angle of arrival information determined from the radio signal;

a processing unit that determines time difference of signal arrival information based on the time of signal arrival information determined by each said signal characterization processing unit; and

a processing unit that determines a probable position of the mobile transceiver based on the time difference of signal arrival information and the collateral information.

2. A method for locating a mobile radio communications transceiver in a wireless communications system that includes two sensor stations of known location, comprising:

receiving, at the two sensor stations, a radio signal from the mobile transceiver;

determining time of signal arrival information based on said radio signal received at the two sensor stations;

determining time difference of signal arrival information based on said time of signal arrival information;

determining collateral information related to a location of the mobile transceiver, wherein the collateral information comprises angle of arrival information that is determined based on said radio signal received at the two sensor stations; and

determining a probable position of the mobile transceiver based on said time difference of signal arrival information and the collateral information.

3. A system for locating a mobile transceiver relative to plural fixed sensor stations, comprising:

(A) a mobile transceiver for transmitting a radio signal;

(B) plural fixed sensor stations, each of said sensor stations for receiving said transmitted signal and each comprising;

(i) means for determining an angle of arrival of said transmitted signal; and

(ii) means for determining a time of arrival of said transmitted signal; and

(C) determination means for determining a probable position of the mobile transceiver based on said angle of arrival and said time of arrival.

4. A system for locating a source of a radio signal, comprising:

(A) an inter-site synchronization mechanism for common time standard maintenance;

(B) plural sensor stations, each sensor station receiving the radio signal, and each sensor station comprising;

(i) an angle of arrival detector for determining an angle of arrival of the radio signal;

(ii) a time of arrival detector for determining a time of arrival, at said sensor station, of an identifiable portion of the radio signal, said time of arrival being determined with respect to said inter-site synchronization mechanism; and

(iii) reporting means for reporting said angle of arrival and said time of arrival; and

(C) a location determining site for receiving said angle of arrival and said time of arrival from each of said plural sensor stations and for determining therefrom a probable position of the source of the radio signal.

5. The system of claim 4, wherein said location determining site determines said probable position by computing a set of locations corresponding to a time-difference-of-arrival of said radio signal at said plural sensor stations and intersecting said set of locations with one of said angles-of-arrival to determine said probable position of the source of the radio signal.

6. The system of claim 4, wherein said plural sensor stations comprises only two sensor stations.

7. A method for determining a location of a source of a radio signal, comprising the steps of:

(A) determining an angle of arrival and a first time of arrival of an identifiable portion of the radio signal at a first sensor station;

(B) determining a second time of arrival of said identifiable portion of the radio signal at a second sensor station, said first sensor station and said second sensor station each having an inter-site synchronization mechanism so said first time of arrival and said second time of arrival are coordinated in time;

(C) determining a locus of points along the surface of the earth based on a ratio of said first time of arrival and said second time of arrival; and

(D) determining, along said locus of points, a point at which an angle of arrival from said first sensor station matches said determined angle of arrival, said point being associated with the source of the radio signal.

8. The method of claim 7, wherein only two sensor stations are used to determine the point.

9. A system for locating a mobile transceiver, comprising:

(a) a mobile transceiver which transmits a signal;

(b) plural means for receiving said signal transmitted by said mobile transceiver, said plural means for receiving being geographically diverse from one another to provide locating coverage over a desired geographic territory; and

(c) means for decoding said signal received by said plural means for receiving, said means for decoding comprising;

(i) means for determining an angle at which said signal from said mobile transceiver arrives at each of said plural means for receiving;

(ii) means for determining a time of arrival of said signal from said mobile transceiver at each of said plural means for receiving,

whereby said means for decoding determines a probable position of said mobile transceiver based on an angle at which said signal arrived at one of said plural means for receiving and times of arrival of said signal determined at more than one of said plural means for receiving.

10. The system of claim 9, wherein said means for decoding determines a time-difference-of-arrival of said signal based on said times of arrival determined at more than one of said plural means for receiving, and wherein said means for decoding determines said probable position by computing a set of locations corresponding to said time-difference-of-arrival and intersecting said set of locations with said angle at which said signal arrived at said one of said plural means for receiving.

11. The system of claim 10, wherein said plural means for receiving comprises only two means for receiving.

12. The system of claim 10, wherein said means for decoding determines said probable position with respect to angles at which said signal arrived at more than one of said plural means for receiving.