Precoding for time or frequency correlated MIMO channels
View Patent ↗Systems and methods are disclosed to generate a codebook for channel state information by generating a random codebook; partitioning channel state information into a set of nearest neighbors for each codebook entry based on a distance metric; and updating the codebook by finding a centroid for each partition.
1. A method of precoding for data transmission comprising:
determining a first precoder for a group of transmitted symbols; and
differentially determining a second precoder for an adjacent group of transmitted symbols,
wherein the second precoder V(s+1) is obtained from the first precoder V(s) as V(s+1) =O V(s) where O is a differential precoder multiplied by V(s) in the order of O V(s) in a non-commutative manner.
2. The method of claim 1 , wherein the adjacent group of transmitted symbols are adjacent in at least one of time, frequency and OFDM tones.
3. The method of claim 1 , where the first precoder and the differential precoder are chosen from a main codebook and a differential codebook, respectively.
4. The method of claim 1 , wherein the second precoder for the adjacent group is derived from the first precoder and differential feedback.
5. The method of claim 2 , wherein channels for the first and the second groups are correlated in at least one of time and frequency.
6. The method of claim 2 , wherein each group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
7. The method of claim 1 , wherein a codebook for the differential precoder O =O(V(s), V(s+1)) is designed such that E └∥O(V(s), V(s +1))V(s)−V(s +1)∥ F 2 ┘ is minimized where E[ ] denotes an expected value and ∥ ∥ F denotes a Frobenius norm.
8. The method of claim 1 , wherein the differential precoder O =O(V(s), V(s+1)) is a unitary matrix.
9. The method of claim 3 , wherein the first precoder is quantized with B 1 bits using the main codebook and the differential precoder is quantized with B 2 bits using the differential codebook where B 2 ≦B 1 .
10. A method of data signal reception comprising:
signaling a first indication of a first precoder for a first group of symbols to be transmitted from a transmitter; and
signaling a second indication of a differential precoder for an adjacent group of symbols to be transmitted from the transmitter,
wherein a second precoder for the adjacent group V(s+1) is obtained from the first precoder V(s) as V(s+1) =O V(s) where O is the differential precoder multiplied by V(s) in the order of O V(s) in a non-commutative manner.
11. The method of claim 10 , wherein the adjacent group of transmitted symbols are adjacent in at least one of time, frequency and OFDM tones.
12. The method of claim 10 , where the first precoder and the differential precoder are chosen from a main codebook and a differential codebook, respectively.
13. The method of claim 10 , wherein the second precoder for the adjacent groups is derived from the first precoder and differential feedback.
14. The method of claim 11 , wherein channels for the first and the second groups are correlated in at least one of time and frequency.
15. The method of claim 11 , wherein each group of transmitted symbols are transmitted in a chunk of adjacent OFDM tones.
16. The method of claim 10 , wherein a codebook for the differential precoder O =O(V(s), V(s+1)) is designed such that E └∥O(V(s), V(s +1))V(s)−V(s +1)∥ F 2 ┘ is minimized where E[ ] denotes an expected value and ∥ ∥ F denotes a Frobenius norm.
17. The method of claim 1 , wherein the differential precoder O =O(V(s), V(s+1)) is a unitary matrix.
18. The method of claim 12 , wherein the first precoder is quantized with B 1 bits using the main codebook and the differential precoder is quantized with B 2 bits using the differential codebook where B 2 ≦B 1 .