Time of arrival estimation positioning systems

• US 6,469,665 B2
• Filed: 04/12/2001
• Issued: 10/22/2002
• Est. Priority Date: 04/25/2000
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (SoftBank Group Corp.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Porcino, Domenico G.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/833,848
• Publication Number:
  US 20010035841A1
• Time in Patent Office: 558 Days
• Field of Search: 342/387, 342/442, 342/457, 342/464, 455/456, 455/457
• US Class Current: 342/387
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A method of determining the location of a mobile radio station comprises estimating the time of arrival of a radio signal travelling between mobile and fixed radio stations and deriving the location from the times of arrival, the method of estimating the time of arrival comprising a first stage of estimation which yields a coarse estimate, the coarse estimate being used to confine the scope of a second stage of estimation which yields a more precise estimate.

Claims

1. A system for determining the location of a mobile radio station relative to radio base stations, comprising

a plurality of radio base stations, each equipped to transmit a signal;

and

a mobile radio station equipped to receive the signal transmitted by each radio base station and having means for estimating the time of arrival of each received signal and means for computing the location of the mobile radio station from the estimated time of arrival of each received signal, wherein the means for estimating the time of arrival comprises

a means for making a first estimate of time of arrival having a first resolution and

a means for making a second estimate of time of arrival having a second resolution, the first estimate of time of arrival contributing to defining the scope of the means for making the second estimate of time of arrival, and the second resolution being more refined than the first resolution.

4. A system as claimed in claim 1, characterised in that the means for making the first estimate of time of arrival comprises means (14) for multiplying a Fast Fourier Transform of a received signal by a Fast Fourier Transform of a replica of a transmitted signal and determining an Inverse Fast Fourier Transform of the resulting product.

5. A system as claimed in claim 1, characterised in that the means for making the second estimate of time of arrival comprises means (16) for performing the time domain correlation of a received signal with a replica of a transmitted signal.

18. The system of claim 1, wherein the first means uses a frequency domain calculation.

19. The system of claim 18, wherein the second means uses a time domain calculation.

21. The method of claim 18, wherein the second stage uses a time domain calculation.

2. Apparatus for estimating the time of arrival of a radio signal transmitted between a fixed radio station and a mobile radio station comprising

first means for making a first estimate of time of arrival, the first means having a first resolution, and

second means for making a second estimate of time of arrival, the second means having a second resolution;

the first estimate of time of arrival contributing to defining the scope of operation of the second means, and the second resolution being more refined than the first resolution,

wherein the first means uses a frequency domain calculation.

3. A system for determining the location of a mobile radio station relative to radio base stations, comprising a mobile radio station equipped to transmit a signal, a plurality of radio base stations, each equipped to receive the signal transmitted by the mobile radio station and having means for estimating the time of arrival of the received signal, and means for computing the location of the mobile radio station from the estimated time of arrival of the signal received at each radio base station;

wherein the means for estimating the time of arrival comprises the apparatus of claim 2.

10. Apparatus as claimed in claim 2, characterised in that the first means for making a first estimate of time of arrival comprises means for multiplying a Fast Fourier Transform of a received signal by a Fast Fourier Transform of a replica of a transmitted signal and determining an Inverse Fast Fourier Transform of the resulting product.

13. A system as claimed in claim 3, characterised in that the means for making the first estimate of time of arrival comprises means for multiplying a Fast Fourier Transform of a received signal by a Fast Fourier Transform of a replica of a transmitted signal and determining an Inverse Fast Fourier Transform of the resulting product.

17. The apparatus of claim 2, wherein the second means uses a time domain calculation.

6. A method of determining the location of a mobile radio station relative to radio base stations, comprising

transmitting a signal from a plurality of radio base stations;

receiving at a mobile radio station the signal transmitted by each radio base station;

estimating the time of arrival of each received signal; and

computing, from the time of arrival estimates, the location of the mobile radio station;

wherein the time of arrival estimation further comprises

making a first stage of estimation having a first resolution and which yields a first estimate of time of arrival; and

making a second stage of estimation having a second resolution and which yields a second estimate of time of arrival;

the first estimate of time of arrival contributing to defining the scope of the second stage of estimation, and the second resolution being more refined than the first resolution.

8. A method as claimed in claim 6, characterised in that the first stage of estimation comprises multiplying (14) a Fast Fourier Transform of a received signal by a Fast Fourier Transform of a replica of a transmitted signal and determining an Inverse Fast Fourier Transform of the resulting product.

9. A method as claimed in claim 6, characterised in that the second stage of estimation comprises performing a time domain correlation (16) of a received signal with a replica of a transmitted signal.

20. The method of claim 6, wherein the first stage uses a frequency domain calculation.

7. A method of determining the location of a mobile radio station relative to radio base stations, comprising

transmitting a signal from a mobile radio station;

receiving at a plurality of radio base stations the signal transmitted by the mobile radio station;

estimating the time of arrival of each received signal; and

computing, from the time of arrival estimates, the location of the mobile radio station;

wherein the time of arrival estimation further comprises

making a first stage of estimation having a first resolution and which yields a first estimate of time of arrival; and

making a second stage of estimation having a second resolution and which yields a second estimate of time of arrival;

the first estimate of time of arrival contributing to defining the scope of the second stage of estimation, and the second resolution being more refined than the first resolution, and

wherein the first stage uses a frequency domain calculation.

15. A method as claimed in claim 7, characterised in that the first stage of estimation comprises multiplying a Fast Fourier Transform of a received signal by a Fast Fourier Transform of a replica of a transmitted signal and determining an Inverse Fast Fourier Transform of the resulting product.

22. The method of claim 7, wherein the second stage uses a time domain calculation.

11. Apparatus for estimating the time of arrival of a radio signal transmitted between a fixed radio station and a mobile radio station comprising

first means for making a first estimate of time of arrival, the first means having a first resolution, and

second means for making a second estimate of time of arrival, the second means having a second resolution;

the first estimate of time of arrival contributing to defining the scope of operation of the second means, and the second resolution being more refined than the first resolution,

characterised in that the second means for making a second estimate of time of arrival comprises means for performing a time domain correlation of a received signal with a replica of a transmitted signal.

12. Apparatus sa claimed in claim 11, characterised in that the means for performing the time domain correlation comprises an NCO.

14. A system for determining the location of a mobile radio station relative to radio base stations, comprising

a mobile radio station equipped to transmit a signal,

a plurality of radio base stations, each equipped to receive the signal transmitted by the mobile radio station and comprising

means for estimating the time of arrival of the received signal, comprising

means for making a first estimate of time of arrival having a first resolution and

means for making a second estimate of time of arrival having a second resolution, the first estimate of time of arrival contributing to defining the scope of the means for making the second estimate of time of arrival, and the second resolution being more refined than the first resolution, and

means for computing the location of the mobile radio station from the estimated time of arrival of the signal received at each radio base station;

charactetised in that the means for making the second estimate of time of arrival comprises means for performing the time domain correlation of a received signal with a replica of a transmitted signal.

16. A method of determining the location of a mobile radio station relative to radio base stations, comprising

transmitting a signal from a mobile radio station;

receiving at a plurality of radio base stations the signal transmitted by the mobile radio station;

estimating the time of arrival of each received signal; and

computing, from the time of arrival, estimates of the location of the mobile radio station;

wherein the time of arrival estimation further comprises

making a first stage of estimation having a first resolution and which yields a first estimate of time of arrival; and

making a second stage of estimation having a second resolution and which yields a second estimate of time of arrival;

the first estimate of time of arrival contributing to defining the scope of the second stage of estimation, and the second resolution being more refined than the first resolution,

characterised in that the second stage of estimation comprises performing a time domain correlation of a received signal with a replica of a transmitted signal.