Codebook construction
A method implemented in a base station used in a wireless communications system is disclosed. The method comprises having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for 4 transmit antenna (4TX) transmission, each codebook including a plurality of precoding matrices, (precoding data with one of the plurality of precoding matrices, and transmitting, to a user equipment, the precoded data, wherein each of the 1-layer and 2-layer codebooks comprises a first codebook and a second codebook, and wherein each precoding matrix in the first codebook comprises a first index and a second index. Other apparatuses, systems, and methods also are disclosed.
1. A method implemented in a user equipment used in a wireless communications system, the method comprising:
receiving, from four transmit antennas of a base station having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for 4 transmit antenna (4TX) transmission, each codebook including a plurality of precoding matrices, precoded data with one of the plurality of precoding matrices; and
decoding, according to the one of the plurality of precoding matrices, the precoded data,
wherein the 1-layer codebook comprises a first 1-layer codebook and a second 1-layer codebook each of which includes a plurality of 4×1 precoding matrices, and the 2-layer codebook comprises a first 2-layer codebook and a second 2-layer codebook each of which includes a plurality of 4×2 precoding matrices, and
wherein each precoding matrix in the first 1-layer and 2-layer codebooks comprises a first index and a second index.
2. The method as in claim 1 , wherein the first index is for a plurality of subbands and the second index is for each subband.
3. The method as in claim 1 , wherein each of the second 1-layer and 2-layer codebooks comprises a legacy codebook or a householder codebook.
4. The method as in claim 1 , wherein each of the 3-layer and 4-layer codebooks comprises a legacy codebook or a householder codebook.
5. The method as in claim 1 , wherein each precoding matrix W in the first 1-layer and 2-layer codebooks satisfies W=W (1) W (2) ,
where first matrix W (1) is chosen from inner codebook (1) , and
second matrix W (2) is chosen from an outer codebook.
6. A base station having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for four transmit antenna (4TX) transmission, each codebook including a plurality of precoding matrices used in a wireless communications system, the base station comprising:
a precoder configured to precode data for decoding according to one of the plurality of precoding matrices; and
a transmitter configured to transmit, to a user equipment, the precoded data,
wherein the 1-layer codebook comprises a first 1-layer codebook and a second 1-layer codebook each of which includes a plurality of 4×1 precoding matrices, and the 2-layer codebook comprises a first 2-layer codebook and a second 2-layer codebook each of which includes a plurality of 4×2 precoding matrices, and
wherein each precoding matrix in the first 1-layer and 2-layer codebooks comprises a first index and a second index.
7. The base station as in claim 6 , wherein the first index is for a plurality of subbands and the second index is for each subband.
8. The base station as in claim 6 , wherein each of the second 1-layer and 2-layer codebooks comprises a legacy codebook or a householder codebook.
9. The base station as in claim 6 , wherein each of the 3-layer and 4-layer codebooks comprises a legacy codebook or a householder codebook.
10. The based station as in claim 6 , wherein each precoding matrix W in the first 1-layer and 2-layer codebooks satisfies W=W (1) W (2) ,
where first matrix W (1) is chosen from inner codebook (1) , and
second matrix W (2) is chosen from an outer codebook.
11. A user equipment used in a wireless communications system, the user equipment comprising:
a receiver configured to receive, from a base station having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for 4 transmission antenna (4TX) transmission, each codebook, including a plurality of precoding matrices, precoded data; and
a decoder configured to decode the precoded data according to the one of the plurality of precoding matrices,
wherein the 1-layer codebook comprises a first 1-layer codebook and a second 1-layer codebook each of which includes a plurality of 4×1 precoding matrices, and the 2-layer codebook comprises a first 2-layer codebook and a second 2-layer codebook each of which includes a plurality of 4×2 precoding matrices, and
wherein each precoding matrix in the first 1-layer and 2-layer codebooks comprises a first index and a second index.
12. The user equipment as in claim 11 , wherein the first index is for a plurality of subbands and the second index is for each subband.
13. The user equipment as in claim 11 , wherein each of the second 1-layer and 2-layer codebooks comprises a legacy codebook or a householder codebook.
14. The user equipment as in claim 11 , wherein each of the 3-layer and 4-layer codebooks comprises a legacy codebook or a householder codebook.
15. The user equipment as in claim 11 , wherein each precoding matrix W in the first 1-layer and 2-layer codebooks satisfies W=W (1) W (2) ,
where first matrix W (1) is chosen from inner codebook (1) , and
second matrix W (2) is chosen from an outer codebook.