Port selection codebook enhancement
Apparatus and methods are provided for port selection codebook configuration. A user equipment (UE) may decode a channel state information (CSI) report configuration (CSI-ReportConfig) from a base station. The CSI-ReportConfig indicates up to L CSI reference signal (CSI-RS) ports for selection by the UE out of P CSI-RS ports configured for measuring and reporting CSI. The UE determines selected CSI-RS ports out of the P CSI-RS ports. The selected CSI-RS ports include the L CSI-RS ports or less. The UE generates a port selection matrix W 1 corresponding to the selected CSI-RS ports. The UE also generates an indication of the port selection matrix W 1 to the base station. The CSI-ReportConfig may further configure the UE to select a subset of frequency basis. The UE determines a selected subset of frequency basis and generates a frequency basis selection matrix W f corresponding to the selected subset of frequency basis.
1. A method for a base station, the method comprising:
generating, at the base station, a channel state information (CSI) report configuration (CSI-ReportConfig) for a user equipment (UE), the CSI-ReportConfig indicating up to L CSI reference signal (CSI-RS) ports for selection by the UE out of P CSI-RS ports configured for measuring and reporting CSI, the CSI-ReportConfig further indicating a subset of frequency basis for the UE to select;
receiving, at the base station, a port selection matrix W 1 from the UE corresponding to selected CSI-RS ports out of the P CSI-RS ports;
receiving, at the base station, a matrix W 2 from the UE comprising compressed combination coefficients;
receiving, at the base station, a frequency basis selection matrix W f corresponding to a selected subset of frequency basis;
configuring a window constrained selection of the subset of the frequency basis, wherein the UE is constrained to select from consecutive k*Mv frequency basis out of N frequency basis, where k is an integer and k*Mv<N;
determining, at the base station, a precoding matrix index (PMI) matrix W=W 1 *W 2 *W f ;
generating, at the base station, physical downlink shared channel (PDSCH) demodulation reference signal (DMRS) transmissions for the UE using the PMI matrix W; and
configuring the UE to select a direct current (DC) frequency basis and any Mv−1 out of N−1 frequency basis, and to report the frequency basis selection matrix W f using a bit width of ┌log 2 (C(N−1, Mv−1))┐.
2. The method of claim 1 , wherein the port selection matrix W 1 is a P×L matrix, wherein each of L columns in the port selection matrix W 1 is P×1 with only one entry in each of the L columns comprising a 1 and other entries in each of the L columns comprising a 0, and wherein different ones of the L columns in the port selection matrix W 1 are not the same as one another.
3. The method of claim 1 , wherein the port selection matrix W 1 is given by
W
1
=
(
W
1
,
1
0
0
W
1
,
1
)
,
wherein W 1,1 is a P/2×L matrix, wherein each of L columns in W 1,1 is P/2×1 with only one entry in each of the L columns comprising a 1 and other entries in each of the L columns comprising a 0, wherein different columns in W 1,1 cannot be the same, and wherein first P/2 CSI-RS ports are horizontally polarized (H-pol) and second P/2 CSI-RS ports are vertically polarized (V-pol).
4. The method of claim 1 , wherein the port selection matrix W 1 is given by
W
1
=
(
W
1
,
1
0
0
W
1
,
2
)
,
wherein W 1,1 and W 1,2 are each a P/2×L matrix, wherein in each of L columns in W 1,1 or W 1,2 only one entry is a 1 and other entries are a 0, wherein different columns in W 1,1 or W 1,2 cannot be the same, and wherein first P/2 CSI-RS ports are horizontally polarized (H-pol) and second P/2 CSI-RS ports are vertically polarized (V-pol).
5. The method of claim 1 , further comprising turning off the frequency basis selection matrix W f , wherein the PMI matrix W degenerates into W=W 1 , wherein the port selection matrix W 1 is a column vector that selects the L CSI-RS ports, wherein the port selection matrix W 1 comprises L non-zero entries, and wherein each of the L non-zero entries comprises a phase and amplitude factor for a combination coefficient for a corresponding port.
6. The method of claim 1 , further comprising turning off the frequency basis selection matrix W f , wherein the PMI matrix W degenerates into W=W 1 W 2 , wherein W 2 comprises more than one column, wherein each column corresponds to a PMI subband, wherein for each column there is at most L non-zero entries, and wherein each of the L non-zero entries comprises a phase and amplitude factor for a combination coefficient for a corresponding port.
7. The method of claim 1 , wherein a total number of PMI subbands for frequency basis selection is N OQISubband *R, where N OQISubband is a number of channel quality indicator (CQI) subbands configured by the base station and R is a size of a CQI subband divided by a size of a PMI subband.
8. The method of claim 1 , further comprising configuring the UE for at least one of wideband channel quality indicator (CQI) reporting and wideband PMI reporting.
9. The method of claim 1 , further comprising receiving, at the base station, an indication from the UE of a location of the consecutive k*Mv frequency basis.
10. The method of claim 1 , further comprising configuring a location of the consecutive k*Mv frequency basis for the UE.
11. The method of claim 1 , wherein the CSI-ReportConfig comprises a list of frequency basis subsets, wherein each entry in the list configures a different subset of frequency basis for the UE to select.
12. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a base station, configure the base station to:
generate, at the base station, a channel state information (CSI) report configuration (CSI-ReportConfig) for a user equipment (UE), the CSI-ReportConfig indicating up to L CSI reference signal (CSI-RS) ports for selection by the UE out of P CSI-RS ports configured for measuring and reporting CSI, the CSI-ReportConfig further indicating a subset of frequency basis for the UE to select;
receive, at the base station, a port selection matrix W 1 from the UE corresponding to selected CSI-RS ports out of the P CSI-RS ports;
receive, at the base station, a matrix W 2 from the UE comprising compressed combination coefficients;
receive, at the base station, a frequency basis selection matrix W f corresponding to a selected subset of frequency basis, wherein the subset of the frequency basis comprises a window constrained selection from consecutive k*Mv frequency basis out of N frequency basis, where k is an integer and k*Mv<N;
determine, at the base station, a precoding matrix index (PMI) matrix W=W 1 *W 2 *W f ;
generate, at the base station, physical downlink shared channel (PDSCH) demodulation reference signal (DMRS) transmissions for the UE using the PMI matrix W; and
configuring the UE to select a direct current (DC) frequency basis and any Mv−1 out of N−1 frequency basis, and to report the frequency basis selection matrix W f using a bit width of ┌log 2 (C(N−1, Mv−1))┐.
13. The non-transitory computer-readable medium of claim 12 , wherein the port selection matrix W 1 is a P×L matrix, wherein each of L columns in the port selection matrix W 1 is P×1 with only one entry in each of the L columns comprising a 1 and other entries in each of the L columns comprising a 0, and wherein different ones of the L columns in the port selection matrix W 1 are not the same as one another.
14. The non-transitory computer-readable medium of claim 12 , wherein the port selection matrix W 1 is given by
W
1
=
(
W
1
,
1
0
0
W
1
,
1
)
,
wherein W 1,1 is a P/2×L matrix, wherein each of L columns in W 1,1 is P/2×1 with only one entry in each of the L columns comprising a 1 and other entries in each of the L columns comprising a 0, wherein different columns in W 1,1 cannot be the same, and wherein first P/2 CSI-RS ports are horizontally polarized (H-pol) and second P/2 CSI-RS ports are vertically polarized (V-pol).
15. The non-transitory computer-readable medium of claim 12 , wherein the port selection matrix W 1 is given by
W
1
=
(
W
1
,
1
0
0
W
1
,
2
)
,
wherein W 1,1 and W 1,2 are each a P/2×L matrix, wherein in each of L columns in W 1,1 or W 1,2 only one entry is a 1 and other entries are a 0, wherein different columns in W 1,1 or W 1,2 cannot be the same, and wherein first P/2 CSI-RS ports are horizontally polarized (H-pol) and second P/2 CSI-RS ports are vertically polarized (V-pol).
16. The non-transitory computer-readable medium of claim 12 , wherein the instructions further configure the base station to turn off the frequency basis selection matrix W f , wherein the PMI matrix W degenerates into W=W 1 , wherein the port selection matrix W 1 is a column vector that selects the L CSI-RS ports, wherein the port selection matrix W 1 comprises L non-zero entries, and wherein each of the L non-zero entries comprises a phase and amplitude factor for a combination coefficient for a corresponding port.
17. The non-transitory computer-readable medium of claim 12 , wherein the instructions further configure the base station to turn off the frequency basis selection matrix W f , wherein the PMI matrix W degenerates into W=W 1 W 2 , wherein W 2 comprises more than one column, wherein each column corresponds to a PMI subband, wherein for each column there is at most L non-zero entries, and wherein each of the L non-zero entries comprises a phase and amplitude factor for a combination coefficient for a corresponding port.