Method and system for an alternating delta quantizer for limited feedback MIMO pre-coders
Aspects of a method and system for an alternating delta quantizer for limited feedback MIMO pre-coders may comprise quantizing a change in channel state information in a MIMO pre-coding system onto at least a first and a second codebook, each of which comprises one or more unitary matrices, using a cost function; feeding back, in an alternating manner, an index to an element of at least the first codebook or the second codebook, associated with the quantizing, from a receiver to a transmitter in said MIMO pre-coding system, and generating the at least first and second codebook based on at least the channel state information. The channel state information may be a matrix V and the cost function may be defined by the following relationship: f ( A ) = ( 1 N ∑ j = 1 N a jj 2 ) where A is a matrix of size N by N and a ij is element (i,j) of matrix A.
1. A method for processing communication signals, the method comprising:
quantizing a change in channel state information in a MIMO pre-coding system onto a plurality of codebooks, comprising at least a first codebook and a second codebook, wherein each of said plurality of codebooks comprises one or more unitary matrices, using a cost function, said cost function is an average of the squared absolute values of the diagonal elements of a matrix A, said matrix A is based on channel state information and the change in channel state information; and
feeding back, in an alternating manner, an index to at least one element in each of said plurality of codebooks, associated with said quantizing, from a receiver to a transmitter in said MIMO pre-coding system.
2. The method according to claim 1 , wherein said channel state information is a matrix V.
3. The method according to claim 2 , comprising generating said matrix V using Singular Value Decomposition (SVD).
4. The method according to claim 2 , comprising generating said matrix V using Geometric Mean Decomposition (GMD).
5. The method according to claim 1 , wherein said cost function ƒ(A) is defined by the following relationship:
f
(
A
)
=
(
1
N
∑
j
=
1
N
a
jj
2
)
where A is said matrix A of size N by N and a ij is element (i,j) of said matrix A.
6. The method according to claim 1 , comprising generating said one or more unitary matrices for at least said first codebook from at least a first set of matrices and a second set of matrices.
7. The method according to claim 6 , comprising generating said first set of matrices from one or more Givens matrices.
8. The method according to claim 1 , comprising modifying a dynamic range of at least said first codebook by modifying a step size of at least said first codebook.
9. The method according to claim 1 , comprising modifying a resolution of at least said first codebook by modifying a cardinality of at least said first codebook.
10. The method according to claim 9 , comprising modifying said cardinality of at least said first codebook by modifying a set of angular levels.
11. The method according to claim 1 , comprising generating Voronoi regions from at least said second codebook for said one or more unitary matrices of at least said second codebook.
12. The method according to claim 11 , comprising generating a set of matrices based on said Voronoi regions and said one or more unitary matrices.
13. The method according to claim 12 , comprising updating at least said second codebook by modifying said set of matrices into a new set of unitary matrices, where said new set of unitary matrices becomes at least said second codebook.
14. The method according to claim 1 , comprising alternating between a plurality of quantization functions during said quantizing.
15. The method according to claim 1 , wherein a communication system comprising said MIMO pre-coding system comprises one or more transmit antennas and one or more receive antennas.
16. The method according to claim 1 , comprising linearly transforming with a combination of a plurality of said unitary matrices, a matrix at a transmitter of said MIMO pre-coding system.
17. The method according to claim 1 , comprising updating said plurality of codebooks based on at least said channel state information.
18. A system for processing communication signals, the system comprising:
one or more circuits in a MIMO pre-coding system, said one or more circuits being operable to:
quantize a change in channel state information onto a plurality of codebooks, comprising at least a first codebook and a second codebook, wherein each of said plurality of codebooks comprises one or more unitary matrices using a cost function, said cost function is an average of the squared absolute values of the diagonal elements of a matrix A, said matrix A is based on channel state information and the change in channel state information; and
feedback, in an alternating manner, an index to at least one element in each of said plurality of codebooks, associated with said quantizing, from a receiver to a transmitter in said MIMO pre-coding system.
19. The system according to claim 18 , wherein said channel state information is a matrix V.
20. The system according to claim 19 , wherein said one or more circuits generate said matrix V using Singular Value Decomposition (SVD).
21. The system according to claim 19 , wherein said one or more circuits generate said matrix V using Geometric Mean Decomposition (GMD).
22. The system according to claim 18 , wherein said cost function ƒ(A) is defined by the following relationship:
f
(
A
)
=
(
1
N
∑
j
=
1
N
a
jj
2
)
where A is said matrix A of size N by N and a ij is element (i,j) of said matrix A.
23. The system according to claim 18 , wherein said one or more circuits generate said one or more unitary matrices for at least said first codebook from at least a first set of matrices and a second set of matrices.
24. The system according to claim 23 , wherein said one or more circuits generate said first set of matrices from one or more Givens matrices.
25. The system according to claim 18 , wherein said one or more circuits modify a dynamic range of at least said first codebook by modifying a step size of at least said first codebook.
26. The system according to claim 18 , wherein said one or more circuits modify a resolution of at least said first codebook by modifying a cardinality of at least said first codebook.
27. The system according to claim 26 , wherein said one or more circuits modify said cardinality of at least said first codebook by modifying a set of angular levels.
28. The system according to claim 18 , wherein said one or more circuits generate Voronoi regions from at least said second codebook for said one or more unitary matrices of at least said second codebook.
29. The system according to claim 28 , wherein said one or more circuits generate a set of matrices based on said Voronoi regions and said one or more unitary matrices.
30. The system according to claim 29 , wherein said one or more circuits update at least said second codebook by modifying said set of matrices into a new set of unitary matrices, where said new set of unitary matrices becomes at least said second codebook.
31. The system according to claim 18 , wherein said one or more circuits alternate between a plurality of quantization functions during said quantizing.
32. The system according to claim 18 , comprising one or more transmit antennas and one or more receive antennas.
33. The system according to claim 18 , comprising linearly transforming with a combination of a plurality said unitary matrices, a matrix at a transmitter of said MIMO pre-coding system.
34. The system according to claim 18 , wherein said one or more circuits update said plurality of codebooks based on at least said channel state information.