Apparatus and method for providing efficient beamforming feedback
An apparatus for a beamformee and a method are provided. The apparatus includes a first beamforming matrix device configured to generate a first beamforming matrix V WB from a channel H; an equivalent channel device configured to generate an equivalent channel {tilde over (H)} k based on the channel H and the first beamforming matrix V WB , where k is a number that indicates a subcarrier index; a second beamforming matrix device configured to obtain a second beamforming matrix V SC from the equivalent channel {tilde over (H)} k ; and a transmitter configured to transmit the first beamforming matrix V WB and the second beamforming matrix V SC .
1. An apparatus for a beamformee, comprising:
a first beamforming matrix device configured to generate a first beamforming matrix V WB from a channel H;
an equivalent channel device configured to generate an equivalent channel {tilde over (H)} k based on the channel H and the first beamforming matrix V WB , where k is a number that indicates a subcarrier index;
a second beamforming matrix device configured to obtain a second beamforming matrix V SC from the equivalent channel {tilde over (H)} k ; and
a transmitter configured to transmit the first beamforming matrix V WB and the second beamforming matrix V SC .
2. The apparatus of claim 1 , further comprising a channel estimator configured to estimate the channel H.
3. The apparatus of claim 1 , wherein the first beamforming matrix V WB has dimension N TX ×K, where N TX is a number of transmit antennas of the apparatus, and where K is a number.
4. The apparatus of claim 1 , wherein the first beamforming matrix V WB is a matrix having K most significant vectors in a right singular matrix, where K is a number.
5. The apparatus of claim 4 , wherein the first beamforming matrix device is further configured to quantize the first beamforming matrix V WB based on the covariance matrix of the channel H.
6. The apparatus of claim 5 , wherein the second beamforming matrix device is further configured to quantize the second beamforming matrix V SC as a quantized beamforming matrix of K×Nc, where K is a number, and where Nc is a number of columns of the quantized beamforming matrix.
7. The apparatus of claim 1 , wherein the first beamforming matrix device is further configured to determine the first beamforming matrix V WB based on a covariance matrix of the channel H.
8. The apparatus of claim 7 , wherein the first beamforming matrix device is further configured to quantize the first beamforming matrix V WB by single value decomposition (SVD).
9. The apparatus of claim 1 , wherein the equivalent channel device is further configured to determine the equivalent channel {tilde over (H)} k by multiplying H k by the first beamforming matrix V WB , where H k is the channel H at the subcarrier index k.
10. The apparatus of claim 1 , wherein the first beamforming matrix V WB is generated to be wideband from a bandwidth that depends on a channel condition and a multiple-input-multiple-output (MIMO) mode.
11. A method, comprising:
determining, by a beamformee, a first beamforming matrix V WB from a channel H;
determining, by the beamformee, an equivalent channel {tilde over (H)} k based on the channel H and the first beamforming matrix V WB , where k is a number that indicates a subcarrier index;
obtaining, by the beamformee, a second beamforming matrix V SC from the equivalent channel {tilde over (H)} k ; and
transmitting, by the beamformee, to a beamformer, the first beamforming matrix V WB and the second beamforming matrix V SC .
12. The method of claim 11 further comprising estimating, by the beamformee, the channel H.
13. The method of claim 11 , wherein the first beamforming matrix V WB has dimension N TX ×K, where N TX is a number of transmit antennas of the beamformer, and where K is a number.
14. The method of claim 11 , wherein the first beamforming matrix V WB is a matrix having K most significant vectors in a right singular matrix, where K is a number.
15. The method of claim 14 , wherein the first beamforming matrix V WB is quantized based on the covariance matrix of the channel H.
16. A method of claim 15 , wherein the second beamforming matrix V SC is quantized as a quantized beamforming matrix of K×Nc, where K is a number, and where Nc is a number of columns of the quantized beamforming matrix.
17. The method of claim 11 , wherein the first beamforming matrix V WB is determined based on a covariance matrix of the channel H.
18. The method of claim 17 , wherein the first beamforming matrix V WB is quantized by single value decomposition (SVD).
19. The method of claim 11 , wherein the equivalent channel {tilde over (H)} k is determined by multiplying H k by the first beamforming matrix V WB , where H k is the channel H at the subcarrier index k.
20. The method of claim 11 , wherein the first beamforming matrix V WB is generated to be wideband from a bandwidth that depends on a channel condition and a multiple-input-multiple-output (MIMO) mode.