Determination of the time delay and/or power of a multicarrier signal

• US 20050243937A1
• Filed: 05/27/2003
• Published: 11/03/2005
• Est. Priority Date: 05/28/2002
• Status: Active Grant

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Callonnec, Denis, Helard, Maryline, Legouable, Rodolphe
• Granted Patent: US 7,711,058 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 5/026 using code division

Abstract

The invention relates to a method of determining the time shift and/or the power of a received signal incorporating a reference sequence (3) and transmitted by multicarrier modulation on a set (M) of carriers spaced from each other by a distance nΔf where n is a natural integer and Δf is a constant. An inverse Fourier transform is applied to the phase variations between components of the signal carried by carriers separated by kΔf for consecutive values of k in order to obtain the impulse response (RI) of the signal and the time shift τ0 and/or the power of the received signal is/are determined from the impulse response by observation of the highest level amplitude peak.

Claims

1. A method of determining the time shift and/or power of a received signal incorporating a reference sequence (3) and transmitted by multicarrier modulation on a set (M) of carriers spaced from each other by a distance nΔ

f where n is a natural integer and Δ

f is a constant, wherein the method comprises;

determining a phase variation representative of the phase variation between two components of the reference sequence of the received signal on two carriers separated by kΔ

f, where k is an integer, for at least two consecutive values of k,

applying an inverse Fourier transform to the representative phase variations obtained in order to obtain the impulse response (RI) of the signal, and

determining the time shift τ

0 and/or the power of the received signal from the impulse response by observation of the highest level amplitude peak.

2. A method according to claim 1, wherein the component of the reference sequence of the received signal on a carrier is obtained by multiplying the component (Ci,p) of the signal received on said carrier by the conjugate (C*j,p) of the component of the reference sequence on that carrier.

3. A method according to claim 2, wherein the representative phase variation for a value of k is determined by calculating the average of the phase variations of a plurality of pairs of components of the received reference sequence conveyed by carriers separated by kΔ

f.

4. A method according to claim 1, wherein, if there is no pair of carriers separated by kΔ

f, the value zero is taken as the phase variation for that value of k.

5. A method according to claim 1, wherein, if there is no pair of carriers separated by kΔ

f, the average of the representative phase variation obtained for the adjacent values of k is taken as the phase variation for that value of k.

6. A method according to claim 1, wherein, for each value of the integer k, the phase variation between two components of the received signal carried by first and second carriers separated by kΔ

f is calculated first, after which the representative phase variation is determined by multiplying the phase variation obtained by the product of the component of the reference sequence on the first carrier and the conjugate of the component of the reference sequence on the second carrier.

7. A method according to claim 6, wherein, for each value of the integer k, the phase variation between a basic component of the signal received on a basic carrier (y_p), chosen as such from the carriers used, and a component obtained by time-delaying k times the basic component with an inter-carrier spacing Δ

f is calculated.

8. The use of the method according to claim 1 in orthogonal frequency division multiplex (OFDM) multicarrier modulation in combination with multicarrier-code division multiple access (MC-CDMA) technique.

9. The use of the method according to claim 1 in multicarrier orthogonal frequency division multiplex (OFDM) modulation in combination with frequency division multiple access (FDMA) technique.

10. The use of the method according to claim 1 in multicarrier orthogonal frequency division multiplex (OFDM) modulation in combination with time division multiple access (TDMA) technique.

11. A receiver circuit adapted to determine the time shift and/or the power of a received signal incorporating a reference sequence and transmitted by multicarrier modulation on a set of carriers spaced from each other by a distance nΔ

f where n is a natural integer and Δ

f is a constant, wherein the circuit comprises;

means for determining a phase variation representative of the phase variation between two components of the reference sequence of the received signal on two carriers separated by kΔ

f, where k is an integer, for at least two consecutive values of k,

means for applying an inverse Fourier transform to the representative phase variations obtained in order to obtain the impulse response of the signal, and

means for determining the time shift and/or the power of the received signal from the impulse response by observation of the highest level amplitude peak.

12. A receiver of signals of the type incorporating a reference sequence and transmitted by multicarrier modulation on a set of carriers spaced from each other by a distance nΔ

f where n is a natural integer and Δ

f is a constant, wherein the receiver comprises;

means for determining a phase variation representative of the phase variation between two components of the reference sequence of the received signal on two carriers separated by kΔ

f, where k is an integer, for at least two consecutive values of k,

means for applying an inverse Fourier transform to the representative phase variations obtained in order to obtain the impulse response of the signal, and

means for determining the time shift and/or the power of the received signal from the impulse response by observation of the highest level amplitude peak.