Method and apparatus for CSI reporting in elevation beamforming and FD-MIMO

1. A method for wireless communication, comprising:

receiving an antenna port configuration message, wherein the antenna port configuration message includes antenna port structure information;

restricting a set of codebooks to a subset of codebooks and a set of codebook type indicator (CTI) values to a subset of CTI values;

identifying, at a user equipment (UE), a CTI that indicates a codebook among the subset of codebooks, wherein the CTI is based at least in part on the subset of CTI values, and wherein the codebook is associated with the antenna port structure information;

selecting a precoding matrix indicator (PMI) based at least in part on the CTI and the subset of codebooks, wherein selecting the PMI based at least in part on the CTI comprises:

selecting a first vertical PMI associated with a first vertical codebook of the subset of codebooks, or selecting a first horizontal PMI associated with a first horizontal codebook of the subset of codebooks, or selecting a second PMI associated with a second codebook of the subset of codebooks, or a combination thereof, wherein one or more of selecting the first vertical PMI, selecting the first horizontal PMI, or selecting the second PMI is based at least in part on the CTI; and

transmitting, from the UE to a base station, a channel state information (CSI) report including the PMI.

2. The method of claim 1 , wherein the CSI report further includes the CTI.

3. The method of claim 1 , wherein the codebook comprises:

a first vertical codebook associated with a number of rows of the two-dimensional antenna port structure; and

a first horizontal codebook associated with a number of columns of the two-dimensional antenna port structure.

4. The method of claim 3 , wherein the codebook further comprises:

a second codebook associated with a number of polarizations of the two-dimensional antenna port structure.

5. The method of claim 1 , further comprising:

receiving, at the UE, a bitmap parameter associated with a restricted codebook size to be applied to the one or more of the first vertical codebook or the first horizontal codebook when restricting the size.

6. The method of claim 1 , wherein selecting the PMI is further based at least in part on a rank indicator (RI).

7. The method of claim 1 , further comprising:

aperiodically transmitting a plurality of CSI reports using a physical uplink shared channel (PUSCH).

8. The method of claim 7 , wherein aperiodically transmitting the plurality of CSI reports using the PUSCH comprises:

aperiodically transmitting the CTI, a rank indicator (RI), a first vertical PMI, a first horizontal PMI, and a channel quality indicator (CQI).

9. The method of claim 1 , further comprising:

periodically transmitting a plurality of CSI reports using a physical uplink control channel (PUCCH).

10. The method of claim 9 , wherein periodically transmitting the plurality of CSI reports using the PUCCH comprises:

transmitting, with a first periodicity, a first CSI report encoding a rank indicator (RI) and a first vertical PMI;

transmitting, with a second periodicity, a second CSI report encoding a first horizontal PMI; and

transmitting, with a third periodicity, a third CSI report encoding a wideband channel quality indicator (CQI) and a second PMI.

11. The method of claim 9 , wherein periodically transmitting the plurality of CSI reports using the PUCCH comprises:

transmitting, with a first periodicity, a first CSI report encoding a rank indicator (RI) and a precoding type indicator (PTI);

transmitting, with a second periodicity, a second CSI report encoding one of a first vertical PMI or a first horizontal PMI based at least in part on the PTI; and

transmitting, with a third periodicity, a third CSI report encoding a wideband channel quality indicator (CQI), a second PMI, and one of the first horizontal PMI or the first vertical PMI based at least in part on the PTI.

12. The method of claim 9 , wherein periodically transmitting the plurality of CSI reports using the PUCCH comprises:

transmitting, with a first periodicity, a first CSI report encoding a rank indicator (RI) and a precoding type indicator (PTI);

transmitting, with a second periodicity, a second CSI report encoding, based at least in part on the PTI, one of a combined first horizontal PMI and first vertical PMI or a combined wideband channel quality indicator (CQI) and a second PMI; and

transmitting, at a third periodicity, a third CSI report encoding, based at least in part on the PTI, one of a combined wideband CQI and the second PMI or a combined subband CQI and the second PMI.

13. The method of claim 9 , wherein transmitting the CSI report comprises:

detecting a collision between the CSI report associated with the base station and a second CSI report;

determining that a first priority associated with the CSI report is higher than a second priority associated with the second CSI report;

dropping the second CSI report; and

transmitting, from the UE to the base station, the CSI report including the PMI.

14. An apparatus for wireless communication, comprising:

means for receiving an antenna port configuration message, wherein the antenna port configuration message includes antenna port structure information;

means for restricting a set of codebooks to a subset of codebooks and a set of codebook type indicator (CTI) values to a subset of CTI values;

means for identifying, at a user equipment (UE), a CTI that indicates a codebook among the subset of codebooks, wherein the CTI is based at least in part on the subset of CTI values, and wherein the codebook is associated with the antenna port structure information;

means for selecting a first horizontal PMI associated with a first horizontal codebook of the subset of codebooks;

means for selecting a second PMI associated with a second codebook of the subset of codebooks;

means for selecting a precoding matrix indicator (PMI) based at least in part on the CTI and the subset of codebooks, wherein selecting the PMI based at least in part on the CTI comprises selecting a first vertical PMI associated with a first vertical codebook of the subset of codebooks, wherein one or more of selecting the first vertical PMI, selecting the first horizontal PMI, or selecting the second PMI is based at least in part on the CTI and the subset of codebooks; and

means for transmitting, from the UE to a base station, a channel state information (CSI) report including the PMI.

15. The apparatus of claim 14 , wherein the CSI report further includes the CTI.

16. The apparatus of claim 14 , further comprising:

means for aperiodically transmitting a plurality of CSI reports using a physical uplink shared channel (PUSCH).

17. The apparatus of claim 14 , further comprising:

means for periodically transmitting a plurality of CSI reports using a physical uplink control channel (PUCCH).