Method and system for controlling a receiver in a digital communication system

1. A method for controlling a receiver in a digital communication system transmitting a frame comprising a periodic sub-set, said method comprising the steps of:

determining a first vector u having a length n;

determining a second vector v shifted by a whole number of periods;

calculating a correlation between said first and second vectors;

calculating a quadratic error between said first and second vectors;

calculating a first cost function F 1 that is a linear combination of both preceding calculations; and

based on the sign of a result of the first cost function F 1 , selectively:

calculating a second cost function F 2 representative of an estimate of the beginning of the frame and determining its minimal value corresponding to the beginning of the frame; and

starting the receiver.

2. A method for controlling a receiver according to claim 1 , wherein the estimate of the beginning of the frame is carried out by using the mean quadratic error between the first vector u and the second vector v according to the formula:

||e −jΔf2πL u−v|| 2

where L is the number of samples separating the vectors u and v.

3. A method for controlling a receiver according to claim 1 , wherein the calculating steps comprise:

calculating the scalar product of the first vector u resulting from an observation window having a length equal to the length of said periodic set, and of the second vector v shifted by a whole number of periods;

calculating the phase drift ΔF resulting from the transmit and receive oscillators, according to the formula:

Δ F =αarg(< u,v >)

with α being a constant;

calculating the mean quadratic error according to the formula:

||e −jΔf2πL u−v|| 2

with L being the number of samples separating the vectors u and v;

calculating the first cost function F 1 based on a linear combination of the scalar product and the mean quadratic error;

comparing the result of the first cost function F 1 to 0; and

if a result of the comparison of the first cost function F 1 to 0 is positive:

calculating a second cost function determining the beginning of frame; and

starting the receiver.

4. A method for controlling a receiver according to claim 3 , wherein α is set to the value ½πnT, with T being the clock period.

5. A receiver control device for controlling a receiver in a digital communication system designed to process a frame comprising a periodic sub-set having a length n, said receiver control device comprising:

a detector configured to:

determine a first vector u having a length n;

determine a second vector v shifted by a whole number of periods;

calculate a correlation between said first and second vectors;

calculate a quadratic error between said first and second vectors;

calculate a first cost function F 1 that is a linear combination of both preceding calculations;

based on the sign of a result of the first cost function F 1 , calculate a second cost function F 2 for seeking a beginning time of the frame; and

based on the sign of a result of the first cost function F 1 , start the receiver.

6. A receiver control device according to claim 5 , wherein the seeking of the beginning time of the frame is carried out by using the mean quadratic error between the first vector u and the second vector v according to the formula:

||e −jΔf2πL u−v|| 2

where L is the number of samples separating the vectors u and v.

7. A receiver control device according to claim 5 , wherein the detector is configured to:

calculate the scalar product of the first vector u resulting from an observation window having a length equal to the length of said periodic set, and of the second vector v;

calculate the phase drift ΔF resulting from the transmit and receive oscillators, according to the formula:

Δ F =αarg(< u,v >)

with α being a constant;

calculate the mean quadratic error according to the formula:

||e −jΔf2πL u−v|| 2

with L being the number of samples separating the vectors u and v;

calculate the first cost function F 1 that is a linear combination of the scalar product and the mean quadratic error;

compare the first cost function F 1 to 0; and

based on a result of the comparison of the first cost function F 1 to 0, determine the beginning time of the frame by calculating a second cost function.

8. A receiver control device according to claim 7 , wherein α is set to the value ½πnT, with T being the clock period.

9. A receiver control device for controlling a receiver in a digital communication system designed to process a frame comprising a periodic sub-set having a length n, the receiver control device being configured to:

determine a first vector u having a length n;

determine a second vector v shifted by a whole number of periods;

calculate a correlation between said first and second vectors;

calculate a quadratic error between said first and second vectors;

calculate a first cost function F 1 that is a linear combination of both preceding calculations;

based on the sign of a result of the first cost function F 1 , calculate a second cost function F 2 for seeking a beginning time of the frame; and

based on the sign of a result of the first cost function F 1 , start the receiver.

10. A receiver control device according to claim 9 , wherein the seeking of the beginning time of the frame is carried out by using the mean quadratic error between the first vector u and the second vector v according to the formula:

||e −jΔf2πL u−v|| 2

where L is the number of samples separating the vectors u and v.

11. A receiver control device according to claim 9 , wherein the receiver control device is configured to:

calculate the scalar product of the first vector u resulting from an observation window having a length equal to the length of said periodic set, and of the second vector v;

calculate the phase drift ΔF resulting from the transmit and receive oscillators, according to the formula:

ΔF =αarg(< u,v >)

with α being a constant;

calculate the mean quadratic error according to the formula:

||e −jΔf2πL u−v|| 2

with L being the number of samples separating the vectors u and v;

calculate the first cost function F 1 that is a linear combination of the scalar product and the mean quadratic error;

compare the first cost function F 1 to 0; and

based on a result of the comparison of the first cost function F 1 to 0, determine the beginning time of the frame by calculating a second cost function.

12. A receiver control device according to claim 11 , wherein α is set to the value ½πnT, with T being the clock period.