Method of minimizing feedback overhead using spatial channel covariance in a multi-input multi-output system
Disclosed is a method for minimizing feedback overhead in a multi-input multi-output (MIMO) communication method using multiple transmission and reception antennas. In particular, a method for minimizing feedback overhead in a multi-input multi-output (MIMO) communication system by using spatial channel covariance, as explicit channel status information (CSI) feedback method is disclosed.
1. A method for performing feedback in a multi-antenna system, the method comprising:
measuring, by a reception end, a spatial channel of the multi-antenna system;
calculating a spatial channel covariance by using the measured spatial channel;
determining feedback information from the calculated spatial channel covariance;
determining whether or not antenna configuration information has been received from the transmission end,
wherein if it is determined that the antenna configuration information has been received from the transmission end, the feedback information is determined with a predefined closed form with respect to a corresponding antenna configuration in the calculated spatial channel covariance; and
transmitting the determined feedback information to a transmission end,
wherein if it is determined that the antenna configuration information has not been received from the transmission end, the feedback information is determined with a certain closed form among all predefined closed forms in the calculated spatial channel covariance,
wherein when a transmission end is a cross-polarized antenna array, the predefined closed form is represented by:
R″ =C(P H R′P),
where P: permutation matrix,
R′: Covariance including the correlation between co-located polarized antenna elements,
C: constant.
2. The method of claim 1 , further comprising: quantizing the determined feedback information.
3. The method of claim 1 , wherein the spatial channel covariance is calculated through a normalization process.
4. The method of claim 1 , wherein the determined feedback information comprises at least one of a constant and a correlation coefficient.
5. The method of claim 1 , wherein the antenna configuration information is classified into a uniform linear array (ULA), a uniform circular array (UCA) or the cross polarized array (CPA).
6. The method of claim 1 , further comprising: reconstructing the spatial channel covariance after the transmission 7 receives the feedback information.
7. The method of claim 6 , further comprising: determining, by the transmission end, a precoding matrix according to the reconstructed spatial channel covariance.
8. The method of claim 1 , wherein the certain closed form is determined by comparing all the predefined closed forms in the calculated spatial channel covariance.
9. The method of claim 1 , wherein the spatial channel covariance is calculated by applying a windowing for a sample average and by performing a normalization process of parameters in a time domain.
10. The method of claim 1 , wherein when four transmission antennas and four reception antennas are provided with the cross-polarized antenna array, the spatial channel covariance is represented by:
R
=
E
{
H
H
H
}
=
4
[
1
0
α
0
0
1
0
α
α
*
0
1
0
0
α
*
0
1
]
where H: spatial channel.
11. The method of claim 1 , wherein the permutation matrix in the predefined closed form is determined by the corresponding antenna configuration.