Interference reduction method

1. A method for reducing interference in a receiver comprising at least two antennas each receiving a signal transmitted through an associated radio propagation channel, the received signals corresponding with the same emitted signal comprising frames of symbols distributed in time and frequency, among which some symbols, called pilot symbols, are known to the receiver, where the said method comprises the following steps:

weighting of each of the signals received with a weighting vector associated respectively with a respective antenna of the receiver;

combination of the weighted signals received to obtain a combined received signal;

weighting of a reference signal comprising pilot symbols with another weighting vector;

comparison of the combined received signal and the weighted reference signal to obtain an error; and

determination of the weighting vectors using a maximum a posteriori criterion by maximising the probability of realisation of the said weighting vectors conditionally with the error obtained.

2. A method according to claim 1 , in which the determination step includes the following sub-steps:

computation of a covariance matrix G B of the propagation channel;

computation of a covariance matrix G D of the propagation channel convoluted with itself; and

determination of the weighting vectors using the covariance matrices G B and G D .

3. A method according to claim 2 , wherein the determination step further comprises a sub-step consisting in decomposing the covariance matrix G B into eigenvectors according to the relation G B =C B Λ B C B H in which C B is an eigenvector matrix of the matrix G B and Λ B is a diagonal matrix comprising the eigenvalues associated with the eigenvectors of the matrix G B and a sub-step consisting in decomposing the covariance matrix G D into eigenvectors according to the relation G D =C D Λ D C D H in which C D is an eigenvector matrix of the matrix G D and Λ D is a diagonal matrix comprising the eigenvalues associated with the eigenvectors of the matrix G D .

4. A method according to claim 3 , wherein the determination step further comprises a sub-step consisting in extracting a matrix C′ B from the matrix C B and a matrix Λ′ B from the matrix Λ B , the matrix Λ′ B comprising a definite number n B ′ of eigenvalues of Λ B and the matrix C′ B comprising the eigenvectors associated with these n B ′ eigenvalues, and a sub-step consisting in extracting a matrix C′ D from the matrix C D and a matrix Λ′ D from the matrix Λ D , the matrix Λ′ D comprising a definite number n D ′ of eigenvalues of Λ D and the matrix C″ D comprising the eigenvectors associated with those n D ′ eigenvalues, the weighting vectors being then determined using the eigenvector matrices C″ B and C′ D and eigenvalue matrices Λ′ B and Λ′ D .

5. A method according to claim 3 , wherein the covariance matrix G B is the Kronecker product of a covariance matrix G B,T in the time domain and a covariance matrix G B,F in the frequency domain and the covariance matrix G D is the Kronecker product of a covariance matrix G D,T in the time domain and a covariance matrix G D,F in the frequency domain, and the determination step comprises the following sub-steps:

decomposition of the covariance matrices G B,T and G B,F into eigenvectors according to the relations G B,T =C B,T Λ B,T C B,T H and G B,F =C B, F Λ B,F C B,F H , in which:

C B,T is an eigenvector matrix of the matrix G B,T ;

Λ B,T is a diagonal matrix comprising eigenvalues associated with the eigenvectors of the matrix G B,T ;

C B,F is an eigenvector matrix of the matrix G B,F ; and

Λ B,F is a diagonal matrix comprising eigenvalues associated with the eigenvectors of the matrix G B,F ;

extraction of a matrix C′ B,T from the matrix C B,T and a matrix Λ′ B,T from the matrix Λ B,T , the matrix Λ′ B,T comprising a definite number n Bt ′ of the largest eigenvalues of Λ B,T and the matrix C′ B,T comprising the eigenvectors associated with these n Bt ′ largest eigenvalues;

extraction of a matrix C′ B,F from the matrix C B,F and a matrix Λ′ B,F from the matrix Λ B,F , the matrix Λ′ B,F comprising a definite number n Bf ′ of the largest eigenvalues of Λ B,F and the matrix C′ B,F comprising the eigenvectors associated with these n Bf ′ largest eigenvalues,

decomposition of the covariance matrices G D,T and G D,F into eigenvectors according to the relations G D,T =C D,T Λ D,T C D,T H and G D,F =C D,F Λ D,F C D,F H , in which:

C D,F is an eigenvector matrix of the matrix G D,T ;

Λ D,T is a diagonal matrix comprising eigenvalues associated with the eigenvectors of the matrix G D,T ;

C D,F is an eigenvector matrix of the matrix G D,F ; and

Λ D,F is a diagonal matrix comprising eigenvalues associated with the eigenvectors of the matrix G D,F ;

extraction of a matrix C′ D,T from the matrix C D,T and a matrix Λ′ D,T from the matrix Λ D,T , the matrix Λ′ D,T comprising a definite number n Dt ′ of the largest eigenvalues of Λ D,T and the matrix C′ D,T comprising the eigenvectors associated with these n Dt ′ largest eigenvalues; and

extraction of a matrix C′ D,F from the matrix C D,F and a matrix A′ D,F from the matrix Λ D,F , the matrix Λ′ D,F comprising a definite number n dF ′ of the largest eigenvalues of Λ D,F and the matrix C′ D,F comprising the eigenvectors associated with these n dF ′ largest eigenvalues, the weighting vectors being then determined using the eigenvector matrices C′ B,T , C′ B,F , C′ D,T , C′ D,F and the eigenvalue matrices Λ′ B,T , Λ′ B,F , Λ′ D,T , Λ′ D,F .

6. A method according to claim 1 , in which the emitted signal is a multicarrier signal, particularly an OFDM signal.

7. A method according to claim 1 , wherein the method steps are executed by one or more processors.

8. Reception equipment comprising at least two antennas capable, each, of receiving a signal transmitted through an associated radio propagation channel, the received signals corresponding with the same emitted signal comprising frames of symbols distributed in time and frequency, among which some symbols, called pilot symbols, are known to the receiver, where the said reception equipment comprises means for the following:

weighting of each of the signals received with a weighting vector associated respectively with a respective antenna of the receiver;

combination of the weighted signals received to obtain a combined received signal;

weighting of a reference signal comprising pilot symbols with another weighting vector;

comparison of the combined received signal and the weighted reference signal to obtain an error; and

determination of the weighting vectors using a maximum a posteriori criterion by maximising the probability of realisation of the said weighting vectors conditionally with the error obtained.