Method and system for utilizing tone grouping with givens rotations to reduce overhead associated with explicit feedback information
View Patent ↗Aspects of a method and system for utilizing tone grouping with Givens rotations to reduce overhead associated with explicit feedback information are presented. In one aspect of the invention, Givens matrices may be utilized to reduce a quantity of information communicated in explicit feedback information via an uplink RF channel. The explicit feedback information may include specifications for a feedback beamforming matrix that may be utilized when transmitting signals via a corresponding downlink RF channel. The feedback beamforming matrix may represent a rotated version of an un-rotated matrix. The Givens matrices may be utilized to apply one or more Givens rotations to un-rotated matrix. The rotated matrix may reduce the quantity of information communicated in the explicit feedback information. The quantity of information communicated in the explicit feedback information may be further reduced by utilizing tone grouping.
1. A method for processing signals, comprising:
in a transmitter that is operable for MIMO communication:
receiving feedback information from a receiver via an uplink RF channel, the feedback information including feedback angles representing a beamforming matrix computed by the receiver for a downlink RF channel, the feedback angles including at least one phase shift angle and at least one Givens rotation angle for each tone group, each said tone group having a tone group size corresponding to a number of frequency carriers of a plurality of frequency carriers on the downlink RF channel included in said tone group;
reconstructing the beamforming matrix using the feedback angles; and
utilizing the beamforming matrix for communication with the receiver on the downlink RF channel.
2. The method of claim 1 , wherein the tone group size is 2.
3. The method of claim 1 , wherein the tone group size is 4.
4. The method of claim 1 , wherein the tone group size is selected from a plurality of tone group sizes supported by the transmitter.
5. The method of claim 1 , wherein the downlink RF channel is a 20 MHz channel.
6. The method of claim 1 , wherein the downlink RF channel is a 40 MHz channel.
7. The method of claim 1 , wherein the beamforming matrix includes a plurality of beamforming factors, each corresponding to one of the plurality of frequency carriers on the downlink RF channel.
8. The method of claim 7 , wherein said reconstructing further includes:
determining a respective one of the beamforming factors corresponding to a select one of the plurality of frequency carriers in each said tone group using the feedback angles;
utilizing an interpolation method to estimate the beamforming factors corresponding to remaining ones of the plurality of frequency carriers in each said tone group using the determined ones of the beamforming factors in each said tone group.
9. The method of claim 8 , wherein the interpolation method is a low pass interpolation method, a linear interpolation method or a cubic interpolation method.
10. The method of claim 1 , wherein said reconstructing further includes:
using an order of said feedback angles to determine an order of multiplications performed to reconstruct the beamforming matrix.
11. A transmitter for use in a MIMO communication system, the transmitter comprising:
one or more processors and/or circuits operable to:
receive feedback information from a receiver via an uplink RF channel, the feedback information including feedback angles representing a beamforming matrix computed by the receiver for a downlink RF channel, the feedback angles including at least one phase shift angle and at least one Givens rotation angle for each tone group, each said tone group having a tone group size corresponding to a number of frequency carriers of a plurality of frequency carriers on the downlink RF channel included in said tone group;
reconstruct the beamforming matrix using the feedback angles; and
enable the beamforming matrix to be utilized for communication with the receiver on the downlink RF channel.
12. The transmitter of claim 11 , wherein the tone group size is 2.
13. The transmitter of claim 11 , wherein the tone group size is 4.
14. The transmitter of claim 11 , wherein the tone group size is selected from a plurality of tone group sizes supported by the transmitter.
15. The transmitter of claim 11 , wherein the downlink RF channel is a 20 MHz channel.
16. The transmitter of claim 11 , wherein the downlink RF channel is a 40 MHz channel.
17. The transmitter of claim 11 , wherein the beamforming matrix includes a plurality of beamforming factors, each corresponding to one of the plurality of frequency carriers on the downlink RF channel.
18. The transmitter of claim 17 , wherein said one or more processors and/or circuits are further operable to:
determine a respective one of the beamforming factors corresponding to a select one of the plurality of frequency carriers in each said tone group using the feedback angles;
utilize an interpolation method to estimate the beamforming factors corresponding to remaining ones of the plurality of frequency carriers in each said tone group using the determined ones of the beamforming factors in each said tone group.
19. The transmitter of claim 18 , wherein the interpolation method is a low pass interpolation method, a linear interpolation method or a cubic interpolation method.
20. The transmitter of claim 11 , wherein said one or more processors and/or circuits are further operable to use an order of said feedback angles to determine an order of multiplications to be performed to reconstruct the beamforming matrix.