Transmit beamforming utilizing codebook selection in a wireless MIMO communication system

1. A method, comprising:

selecting, at a transceiver, a sub-matrix from an estimated multiple input, multiple output (MIMO) channel matrix, wherein the estimated MIMO channel matrix is constructed based on a codebook;

calculating, at the transceiver, a singular value decomposition (SVD) based on the sub-matrix; and

calculating, at the transceiver, a steering matrix based on the SVD and the codebook.

2. The method of claim 1 , wherein the estimated MIMO channel matrix has three columns;

wherein selecting the sub-matrix comprises selecting two of the three columns of the estimated MIMO channel matrix.

3. The method of claim 1 , wherein selecting the sub-matrix comprises generating a QR decomposition of the sub-matrix, wherein the QR decomposition includes an R matrix;

wherein calculating the SVD based on the sub-matrix comprises calculating an SVD of the R matrix.

4. The method of claim 1 , further comprising:

calculating, at the transceiver, a correlation matrix based on the sub-matrix;

wherein calculating the SVD based on the sub-matrix comprises calculating an SVD of the correlation matrix.

5. The method of claim 1 , wherein the estimated MIMO channel matrix has four columns;

wherein selecting the sub-matrix comprises selecting two of the four columns of the estimated MIMO channel matrix to form a 2-column sub-matrix.

6. The method of claim 1 , wherein the estimated MIMO channel matrix has four columns, and wherein selecting the sub-matrix comprises:

selecting three columns of the estimated MIMO channel matrix;

calculating signal to noise ratio (SNR) values associated with the selected three columns of the estimated MIMO channel matrix; and

selecting two columns of the selected three columns of the estimated MIMO channel matrix based on the SNR values.

7. The method of claim 1 , wherein selecting the sub-matrix comprises forming a 2-column sub-matrix.

8. The method of claim 7 , further comprising generating a QR decomposition of the 2-column sub-matrix, wherein the QR decomposition includes an R matrix;

wherein calculating the SVD based on the sub-matrix comprises calculating an SVD of the R matrix.

9. The method of claim 7 , further comprising:

calculating a correlation matrix based on the 2-column sub-matrix;

wherein calculating the SVD based on the sub-matrix comprises calculating an SVD of the correlation matrix.

10. The method of claim 1 , wherein selecting the sub-matrix from the estimated MIMO channel matrix comprises:

selecting a column in the estimated MIMO channel matrix with the largest norm;

projecting each of the remaining columns in the estimated MIMO channel matrix to the null space spanned by the column in the estimated MIMO channel matrix with the largest norm; and

selecting a next column based on the projections of the remaining columns.

11. The method of claim 1 , further comprising:

transmitting, at the transceiver, a training signal; and

receiving, at the transceiver, the estimated MIMO channel matrix.

12. The method of claim 1 , further comprising:

receiving, at the transceiver, a training signal; and

constructing, at the transceiver, the estimated MIMO channel matrix based on the training signal and the codebook.

13. An apparatus, comprising:

a sub-matrix selector to select a sub-matrix from an estimated multiple input, multiple output (MIMO) channel matrix, wherein the estimated MIMO channel matrix constructed based on a codebook;

a singular value decomposition (SVD) calculator to calculate an SVD based on the sub-matrix; and

a steering matrix generator to calculate a steering matrix based on the SVD and the codebook.

14. The apparatus of claim 13 , wherein the estimated MIMO channel matrix has three columns;

wherein the sub-matrix selector is configured to select two of the three columns of the estimated MIMO channel matrix.

15. The apparatus of claim 13 , wherein the sub-matrix selector includes a QR decomposition calculator to generate an R matrix;

wherein the SVD calculator is configured to calculate an SVD of the R matrix.

16. The apparatus of claim 13 , wherein the SVD calculator includes a correlation matrix calculator;

wherein the SVD calculator is configured to calculate an SVD of a correlation matrix corresponding to the sub-matrix.

17. The apparatus of claim 13 , wherein the estimated MIMO channel matrix has four columns;

wherein the sub-matrix selector is configured to select two of the four columns of the estimated MIMO channel matrix to form a 2-column sub-matrix.

18. The apparatus of claim 13 , wherein the estimated MIMO channel matrix has four columns, and wherein the sub-matrix selector is configured to:

select three columns of the estimated MIMO channel matrix;

calculate signal to noise ratio (SNR) values associated with the selected three columns of the estimated MIMO channel matrix; and

select two columns of the selected three columns of the estimated MIMO channel matrix based on the SNR values.

19. The apparatus of claim 13 , wherein the sub-matrix selector is configured to select a 2-column sub-matrix.

20. The apparatus of claim 19 , further comprising a QR decomposition processor to generate a 2×2 R matrix corresponding to the 2-column sub-matrix;

wherein the SVD calculator is configured to calculate an SVD of the R matrix.

21. The apparatus of claim 19 , wherein the SVD calculator includes a correlation matrix calculator to calculate a correlation matrix based on the 2-column sub matrix;

wherein calculating the SVD based on the sub-matrix comprises calculating an SVD of the correlation matrix.

22. The apparatus of claim 13 , wherein the sub-matrix selector is configured to:

select a column in the estimated MIMO channel matrix with the largest norm;

project each of the remaining columns in the estimated MIMO channel matrix to the null space spanned by the column in the estimated MIMO channel matrix with the largest norm; and

select a next column based on the projections of the remaining columns.

23. The apparatus of claim 13 , further comprising a channel matrix estimator to construct the estimated MIMO channel matrix based on the codebook.

24. An apparatus, comprising:

a processor configured to:

select a sub-matrix from an estimated multiple input, multiple output (MIMO) channel matrix, wherein the estimated MIMO channel matrix constructed based on a codebook;

calculate a singular value decomposition (SVD) based on the sub-matrix; and

calculate a steering matrix based on the SVD and the codebook; and

a memory coupled to the processor.

25. The apparatus of claim 24 , wherein the processor is further configured to construct the estimated MIMO channel matrix based on the codebook.