Methods and apparatus for port selection codebook enhancement
Apparatus and methods are provided for port selection codebook configuration. A user equipment (UE) may receive, from a base station, an indication of parameter settings of a port selection codebook. The port selection codebook includes a port selection matrix W 1 , a combinational coefficient matrix W 2 , and a frequency basis selection matrix W f . Based at least in part on the parameter settings, the UE selects L CSI-RS ports, Mv frequency basis from a window of N consecutive frequency basis; and up to beta*L*Mv entries per layer, where beta is a percentage of the L*Mv entries per layer. The UE reports one or more of the port selection matrix W 1 , the up to beta*L*Mv entries in the combinational coefficient matrix W 2 per layer, and the frequency basis selection matrix W f to the base station.
1. A method for a base station, the method comprising:
transmitting, from the base station to a user equipment (UE), an indication of parameter settings of a port selection codebook, the port selection codebook comprising a port selection matrix W 1 , a combinational coefficient matrix W 2 , and a frequency basis selection matrix W f , the indication of the parameter settings including:
for the port selection matrix W 1 , up to L channel state information reference signal (CSI-RS) ports out of P CSI-RS ports configured for measuring and reporting channel state information (CSI), wherein L is a first value indicated in the parameter settings;
for the frequency basis selection matrix W f , Mv frequency basis from a window of N consecutive frequency basis, wherein Mv is a second value indicated in the parameter settings; and
for the combinational coefficient matrix W 2 , up to beta*L*Mv entries per layer, wherein beta is a third value indicated in the parameter settings and corresponds to a percentage of the L*Mv entries per layer;
receiving, at the base station from the UE, the port selection matrix W 1 , the combinational coefficient matrix W 2 , and the frequency basis selection matrix W f ;
determining, at the base station, a precoding matrix index (PMI) matrix W=W 1 *W 2 *W f ; and
generating, at the base station, a physical downlink shared channel (PDSCH) and its demodulation reference signal (DMRS) transmission for the UE using the PMI matrix W.
2. The method of claim 1 , wherein the parameter settings include a value of L that is independent of a value of P, except that the value of L is less than or equal to the value of P.
3. The method of claim 1 , wherein the parameter settings include a value of L selected from a range that depends on a value of P.
4. The method of claim 3 , wherein for a lower value of P the range includes lower values of L and higher values of L, and for a higher value of P the range includes only the lower values of L.
5. The method of claim 3 , wherein for a lower value of P the range includes lower values of L and higher values of L, and for a higher value of P the range includes only the higher values of L.
6. The method of claim 1 , wherein the port selection matrix W 1 is polarization common, frequency basis common, and layer independent, and wherein receiving the port selection matrix W 1 from the UE comprises independently receiving for each layer regardless of the polarization and frequency basis, where is a layer index.
7. The method of claim 1 , wherein the port selection matrix W 1 is polarization common, frequency basis common, and layer common, and wherein receiving the port selection matrix W 1 from the UE comprises receiving a single port selection matrix W 1 regardless of polarization, frequency basis, and layer.
8. The method of claim 1 , wherein receiving, from the UE, the up to beta*L*Mv entries in the combinational coefficient matrix W 2 per layer further comprises receiving a bitmap reporting locations of the up to beta*L*Mv entries of the combinational coefficient matrix W 2 per layer unless one or more conditions are met, wherein the one or more conditions comprise beta=1, the base station configured the locations of the up to beta*L*Mv entries, the UE is not configured to report the frequency basis selection matrix W f , and Mv=1.
9. The method of claim 8 , wherein the bitmap is frequency basis independent, polarization independent, and layer independent.
10. The method of claim 8 , wherein the bitmap is frequency basis independent, and wherein the bitmap is at least one of polarization common and layer common.
11. The method of claim 1 , further comprising receiving, from the UE, a report comprising a bitwidth of ┌log 2 (L*Mv)┐ per layer indicating a strongest coefficient indicator (SCI) corresponding to a location of a strongest coefficient among the up to beta*L*Mv entries of the combinational coefficient matrix W 2 .
12. The method of claim 1 , further comprising receiving, from the UE, a report comprising a bitwidth of ┌log 2 (L)┐ per layer indicating a strongest coefficient indicator (SCI) corresponding to a location of a strongest coefficient among the up to beta*L*Mv entries of the combinational coefficient matrix W 2 .
13. The method of claim 12 , wherein the predetermined frequency basis corresponds to a zero frequency component.
14. The method of claim 1 , further comprising:
receiving, from the UE, a first report of a first strongest coefficient among the up to beta*L*Mv entries of the combinational coefficient matrix W 2 per layer, the first strongest coefficient corresponding to a first polarization; and
receiving, from the UE, a second report of a second strongest coefficient corresponding to a second polarization, wherein the second polarization is different than the first polarization.
15. The method of claim 14 , further comprising determining, based on an implicit indication from the UE, a location of the second strongest coefficient corresponding to the second polarization.
16. The method of claim 14 , wherein the second report uses a bitwidth of ┌log 2 ((L−1)*Mv)┐ per layer to report a strongest coefficient indicator (SCI) corresponding to a location of the second strongest coefficient corresponding to the second polarization.
17. The method of claim 14 , further comprising receiving, from the UE, a predetermined value of an amplitude coefficient indicator indicating that no values are fed back to the base station for non-zero coefficients that correspond to the second polarization.
18. The method of claim 1 , further comprising receiving, from the UE, a predetermined value of an amplitude coefficient indicator indicating an error in reporting an amplitude coefficient, an extended value of an amplitude coefficient, or use of a selected channel state information compression.
19. The method of claim 1 , further comprising configuring the UE with N=Mv or N>Mv for selecting the Mv frequency basis from the window of N consecutive frequency basis, wherein when N>Mv, N=2*Mv.
20. The method of claim 1 , wherein the frequency basis selection matrix W f received from the UE comprises a direct current (DC) frequency basis, and wherein the frequency basis selection matrix W f is received using a bitwidth of
⌈
log
2
{
C
(
Mv
-
1
N
-
1
)
}
⌉
where
C
(
Mv
-
1
N
-
1
)
represents combinatorial possibilities of selecting Mv−1 from N−1 elements.