Method for Estimating the Distance of a Receiver from a Radio Transmitter, Relative Methods for Calculating the Position of a Mobile Terminal, Mobile Terminal and Localization Device

• US 20130310074A1
• Filed: 02/27/2012
• Published: 11/21/2013
• Est. Priority Date: 02/25/2011
• Status: Active Grant

• Current Assignee: Emergent Mobile LLC
• Original Assignee: Sisvel Technology S.r.l. (Fineur International S.A.)
• Inventors: Porzio Giusto, Pietro
• Granted Patent: US 9,319,840 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: H04W 4/023 using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
• 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 estimating the distance (d) of a receiver (102) from a radio transmitter (101) includes the steps of: receiving (602) radio signals (103, 701) irradiated by the transmitter (101), which include components from which at least three tones (1,2,3,4) are extracted, each having a different frequency; measuring (606) a first phase difference (Δφ₂₁) between first two tones (1, 2) of the at least three tones, whose frequencies (f₁, f₂) have a first spacing, and measuring a second phase difference (Δφ₄₃) between second two tones (3, 4) of the at least three tones, whose frequencies (f₃, f₄) have a second spacing, wherein one of the first spacing or second spacing is greater than the other; estimating (607, 611, 613) the distance (d) on the basis of the first phase difference (Δφ₂₁) and the second phase difference (Δφ₄₃).

Claims

1. A method for estimating the distance of a radio receiver from a radio transmitter comprising the steps of:

receiving radio signals irradiated by said transmitter, said radio signals comprising components from which at least three tones are extracted, each having a different frequency;

measuring a first phase difference between first two tones of said at least three tones, whose frequencies have a first spacing, and measuring a second phase difference between second two tones of said at least three tones, whose frequencies have a second spacing, wherein one of said first spacing or second spacing is greater than the other;

estimating said distance on the basis of said first phase difference and said second phase difference.

2. A method according to claim 1, wherein said distance is estimated by comparing a first estimate of said distance based on said first phase difference with at least a second estimate of said distance based on said second phase difference.

3. A method according to claim 1, wherein said radio signals correspond to an OFDM signal comprising a plurality of subcarriers from which a plurality of corresponding tones is extractable.

4. A method according to claim 3, wherein said subcarriers are equally spaced in frequency, and wherein the smaller one of said first spacing and second spacing is equal to the spacing between said plurality of subcarriers.

5. A method according to claim 1, wherein said two tones whose frequencies have said greater spacing are selected depending on an uncertainty associated with said phase difference measured between said two tones whose frequencies have said smaller spacing.

6. A method according to claim 1, further providing a correction of the estimate of said distance, which takes into account the difference between an estimated distance and the length of the direct propagation path of said radio signals, on the basis of the characteristics of the transfer function of the radio channel.

7. A mobile terminal comprising at least one antenna for receiving radio signals, means for extracting tones from said received radio signals, means for measuring phase differences between said tones, and means for implementing the method according to claim 1.

8. A method for calculating the position of a mobile terminal receiving radio signals from a plurality of base stations whose geographic positions are known, the method comprising the steps of:

receiving signals at said mobile terminal from at least three of said base stations;

estimating the relative distances between said mobile terminal and each one of said at least three base stations, by using the method for estimating the distance according to claim 1;

calculating the position of said mobile terminal by multilateration with respect to said at least three base stations.

9. A method according to claim 8, wherein said mobile terminal acts as said radio receiver and each one of said base stations acts as a radio transmitter.

10. A method according to claim 8, wherein when calculating said position a weight is associated with each one of said estimated relative distances, said weight being a function of at least one of the following parameters:

signal attenuation, signal distortion, delay of at least one subcarrier of the signal.

11. A mobile terminal comprising at least one antenna for receiving radio signals from at least three base stations, means for extracting tones from said received radio signals, means for measuring phase differences between said tones, further comprising means for implementing the method according to claim 8.

12. A method for calculating the position of a mobile terminal belonging to a radio mobile network comprising a plurality of base stations, the method comprising the steps of:

receiving radio signals transmitted by said mobile terminal to at least three of said base stations;

estimating the relative distances between said mobile terminal and each one of said at least three base stations by using the method for estimating the distance according to claim 1;

calculating the position of said mobile terminal by multilateration with respect to said at least three base stations.

13. A method according to claim 12, wherein said mobile terminal acts as said radio transmitter and each one of said base stations acts as a radio receiver.

14. A device for localizing mobile terminals, wherein said device is operationally connected to at least three base stations of a radio mobile network, further comprising means for implementing the method according to claim 12.