Beam and power allocation method for MIMO communication system
View Patent ↗The present invention provides the multiuser Multiple-Input Multiple-Output (MIMO) systems with a feedback method which includes measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas, selecting one of precoding matrixes, which has best SNRs, retrieving an index mapped to the selected preceding matrix from a predetermined mapping table, and transmitting the index with the SNRs of the selected precoding matrix. In the present invention, it is possible to reduce feedback information amount without degradation of the sum rate performance of the system since the feedback information is transmitted in a form of index implying appropriate precoding matrix and corresponding SNRs.
1. A method for transmitting data in multiuser Multiple-Input Multiple-Output (MIMO) systems in which a base station performs scheduling on the basis of feedback information received from a plurality of terminals, comprising:
determining, at the base station, at least one best terminal for each transmit antenna on the basis of the feedback information;
calculating a sum rate from the feedback information;
deciding a precoding matrix and terminals for each transmit antenna, maximizing the sum rate; and
performing transmission with the decided precoding matrix and terminals;
wherein the best terminal for each antenna is determined by
k
i
,
j
=
arg
max
k
I
^
{
1
,
2
,
…
,
K
}
r
k
,
i
,
j
,
where r k,i,j is a received Signal to Noise Ratio (SNR) of kth terminal, i is an index of the precoding matrix, and I is an index of a column of the precoding matrix.
2. The method of claim 1 , wherein the feedback information includes all indexes of the precoding matrixes and received SNRs corresponding to the matrixes.
3. A method for transmitting data in multiuser Multiple-Input Multiple-Output (MIMO) systems in which a base station performs scheduling on the basis of feedback information received from a plurality of terminals, comprising:
determining, at the base station, at least one best terminal for each transmit antenna on the basis of the feedback information;
calculating a sum rate from the feedback information;
deciding a precoding matrix and terminals for each transmit antenna, maximizing the sum rate; and
performing transmission with the decided precoding matrix and terminals;
wherein the precoding matrix is selected by
W
CF
1
,
k
=
arg
max
i
,
j
r
k
,
i
,
j
,
where r k,i,j is a received SNR of a kth terminal, i is an index of the precoding matrix, and j is an index of a column of the precoding matrix.
4. The method of claim 3 , wherein the feedback information includes a single index of a precoding matrix chosen by the terminal and SNRs corresponding to the precoding matrix.
5. The method of claim 3 , wherein the feedback information includes a column vector of a precoding matrix selected by the terminal and the received SNR corresponding to the column vector.
6. A method for transmitting data in multiuser Multiple-Input Multiple-Output (MIMO) systems in which a base station performs scheduling on the basis of feedback information received from a plurality of terminals, comprising:
determining, at the base station, at least one best terminal for each transmit antenna on the basis of the feedback information;
calculating a sum rate from the feedback information;
deciding a precoding matrix and terminals for each transmit antenna, maximizing the sum rate; and
performing transmission with the decided precoding matrix and terminals;
wherein the precoding matrix is selected by
W
CF
2
,
k
=
arg
max
i
å
j
c
f
(
r
k
,
i
,
j
)
,
where c f feedback capacity, r k,i,j is a received SNR of kth terminal, i is an index of the precoding matrix, and j is an index of a column of the precoding matrix.
7. The method of claim 6 , wherein the feedback information includes a single index of a precoding matrix chosen by the terminal and SNRs corresponding to the precoding matrix.
8. A method for feeding back information in multiuser Multiple-Input Multiple-Output (MIMO) system in which a base station determining at least one best terminal for each transmit antenna on the basis of feedback information, calculating a sum rate from the feedback information, deciding a precoding matrix and terminals for each transmit antenna, performing transmission with the decided precoding matrix and terminals, the method comprising:
measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas;
selecting one of precoding matrixes, which has a best SNR;
retrieving an index mapped to the selected precoding matrix from a predetermined mapping table; and
transmitting the index with the SNRs of the selected precoding matrix;
wherein the precoding matrix is selected by
W
CF
1
,
k
=
arg
max
i
,
j
r
k
,
i
,
j
,
where r k,i,j is a received SNR of a kth terminal, i is the index of the precoding matrix, and j is the index of a column of the precoding matrix.
9. A method for feeding back information in multiuser Multiple-Input Multiple-Output (MIMO) system in which a base station determining at least one best terminal for each transmit antenna on the basis of feedback information, calculating a sum rate from the feedback information, deciding a precoding matrix and terminals for each transmit antenna, performing transmission with the decided precoding matrix and terminals, the method comprising:
measuring at the terminal received Signal to Noise Ratios SNRs for all transmit antennas;
selecting one of precoding matrixes, which has a best SNR;
retrieving an index mapped to the selected precoding matrix from a predetermined mapping table; and
transmitting the index with the SNRs of the selected precoding matrix;
wherein the precoding matrix is selected by
W
CF
1
,
k
=
arg
max
i
,
j
r
k
,
i
,
j
,
where c f is feedback capacity, r k,i,j is a received SNR of a kth terminal, i is the index of the precoding matrix, and j is an index of a column of the precoding matrix.
10. A method for feeding back information of multiuser Multiple-Input Multiple-Output (MIMO) system in which a base station determining at least one best terminal for each transmit antenna on the basis of feedback information, calculating a sum rate from the feedback information, deciding a precoding matrix and terminals for each transmit antenna, performing transmission with the decided precoding matrix and terminals, the method comprising:
measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas;
selecting one of precoding matrixes, which has best SNRs;
extracting one of column vectors constituting the selected precoding matrix;
retrieving an index mapped to the selected precoding matrix from a predetermined mapping table; and
transmitting the index with information on the retrieved column vector and the SNRs corresponding to the column vector to the base station;
wherein the precoding matrix is selected by
W
CF
1
,
k
=
arg
max
i
,
j
r
k
,
i
,
j
,
where r k,i,j is a received SNR of a kth terminal, i is the index of the precoding matrix, and j is an index of a column of the precoding matrix.
11. A method for feeding back information of multiuser Multiple-Input Multiple-Output (MIMO) system in which a base station determining at least one best terminal for each transmit antenna on the basis of feedback information, calculating a sum rate from the feedback information, deciding a precoding matrix and terminals for each transmit antenna, performing transmission with the decided precoding matrix and terminals, the method comprising:
measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas;
selecting one of precoding matrixes having a best SNR;
extracting one of column vectors constituting the selected precoding matrix;
retrieving an index mapped to the selected precoding matrix, column vector, and SNR corresponding to the column vector of the selected precoding matrix from a predetermined mapping table; and
transmitting the index as the feedback information to the base station;
wherein the precoding matrix is selected by
W
CF
1
,
k
=
arg
max
i
,
j
r
k
,
i
,
j
,
where r k,i,j is a received SNR of a kth terminal, i is the index of precoding matrix, and j is the index of a column of the precoding matrix.