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\xd72 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.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A stem cell preservation medium for preserving stem cells which comprises hydroxyethyl starch (HES), dimethyl sulfoxide (DMSO) and ethylene glycol (EG), wherein
ethylene glycol (EG) is present in a concentration range of 4% to 12.5% (vv),
hydroxyethyl starch (HES) is present in a concentration range of 4% to 8% (wv), and
dimethyl sulfoxide (DMSO) is present in a concentration range of 4% to 6% (vv).
2. (canceled)
3. (canceled)
4. (canceled)
5. The stem cell preservation medium according to claim 1 which is free of any one of: serum, a substitute component of serum, a protein component and an animal-derived component.
6. A stem cell preservation method for slow-freezing stem cells,
comprising:
a dissociation step for dissociating the stem cells by using a pronase solution; and
a freezing step for slow-freezing the thus dissociated stem cells in a stem cell preservation medium, wherein
the stem cell preservation medium comprising hydroxyethyl starch (HES), dimethyl sulfoxide (DMSO) and ethylene glycol (EG),
the method also comprising a thawing step for conducting rapid thawing after a freezing step, wherein
the thawing step effects rapid thawing by adding a warm culture medium to a cryotube or effect thawing in a water bath.
7. The stem cell preservation method according to claim 6, wherein the size of clumps is from 200 \u03bcm2 to 10000 \u03bcm2 in the dissociation step.
8. The stem cell preservation method according to claim 6, wherein stem cells of the stem cell preservation medium are present in a range of 1\xd7103 to 1\xd7106 per mL of the preservation medium in the freezing step.
9. The stem cell preservation method according to claim 8, wherein the stem cell preservation medium is approximately 0.2 mL to 1 mL per cryotube in the freezing step.
10. The stem cell preservation method according to claim 6, wherein
ethylene glycol (EG) is present in a concentration range of 2% to 15% (vv).
11. The stem cell preservation method according to claim 6, wherein
hydroxyethyl starch (HES) is present in a concentration range of 4% to 8% (wv).
12. The stem cell preservation method according to claim 6, wherein
dimethyl sulfoxide (DMSO) is present in a concentration range of 4% to 6% (vv).
13. The stem cell preservation method according to claim 6, wherein the culture medium contains a culture medium which is selected from a group consisting of a Dulbecco modified Eagle medium (DMEM culture medium) and an F12 culture medium or a mixture thereof.
14. The stem cell preservation method according to claim 6, wherein an albumin solution is present at the concentration of approximately 4% (wv).
15. (canceled)
16. The stem cell preservation method according to claim 6, wherein there is additionally included a cultivation step in which after the thawing step, cultivation is performed in a warm culture medium to which a ROCK inhibitor has been added.
17. The stem cell preservation method according to claim 6, wherein the stem cells are stem cells selected from a group consisting of tissue stem cells, embryonic stem (ES) cells and induced pluripotent stem (iPS) cells.
18. A stem cell preservation system for preserving stem cells,
comprising:
a pronase solution as dissociation means for dissociating the stem cells;
a stem cell preservation medium according to claim 1; and
slow freezing means for slow-freezing said dissociated stem cells in the stem cell preservation medium.
19. The stem cell preservation medium according to claim 1 which is used for preserving stem cells from which the stem cells have been dissociated by using a pronase solution.
20. The stem cell preservation medium according to claim 1, wherein
ethylene glycol (EG) is present in a concentration range of 4% to 10% (vv), and a survival rate can be recovered stably at 60% or higher, irrespective of which thawing process is carried out, that is, thawing for effecting rapid thawing by adding a warm culture medium to a cryotube or thawing in a water bath.
21. The stem cell preservation medium according to claim 19, wherein
ethylene glycol (EG) is present in a concentration range of 4% to 10% (vv), and a survival rate can be recovered stably at 60% or higher, irrespective of which thawing process is carried out, that is, thawing for effecting rapid thawing by adding a warm culture medium to a cryotube or thawing in a water bath.