Beam combining based channel state information (CSI) feedback

1. An apparatus comprising:

one or more processors, wherein to configure a user equipment (UE) for channel state information (CSI) reporting in a cellular network, the one or more processors are configured to:

receive, in a radio resource control (RRC) configuration message, first configuration information to configure determination of channel quality information (CQI), a rank indicator (RI), and a precoding matrix indicator (PMI) for the CSI reporting;

receive second configuration information to configure codebook parameters for a high spatial resolution codebook associated with the PMI;

determine a precoding matrix based on the first configuration information, wherein a number of coefficients in at least one coefficient vector for reporting the precoding matrix is configured utilizing the second configuration information; and

transmit CSI for transmission to a base station, the CSI including the RI and the PMI associated with the determined precoding matrix.

2. The apparatus of claim 1 , wherein the PMI corresponds to a linear combination of mutually orthogonal discrete Fourier transform (DFT) beams.

3. The apparatus of claim 2 , wherein a number of the mutually orthogonal DFT beams is configured for respective ranks of a plurality of ranks based on the first configuration information.

4. The apparatus of claim 1 , wherein the second configuration information configures a maximum number of coefficients for a first transmission layer of a plurality of available transmission layers, and wherein the one or more processors are configured to:

receive third configuration information configuring a maximum number of coefficients for a second transmission layer of the plurality of available transmission layers.

5. The apparatus of claim 4 , wherein the one or more processors are configured to:

determine the precoding matrix further based on the second and third configuration information, wherein a number of coefficients for the first transmission layer is configured utilizing the second configuration information, and a number of coefficients for the second transmission layer is configured utilizing the third configuration information.

6. The apparatus of claim 1 , wherein second configuration information configures a maximum number of coefficients for reporting per transmission layer of a plurality of available transmission layers.

7. The apparatus of claim 1 , wherein the number of coefficients reported in the PMI is configured for a respective rank of a plurality of ranks based on the first configuration information.

8. The apparatus of claim 1 , wherein the one or more processors are configured to:

configure a subset of the coefficients associated with the determined PMI to a value of 0 based on the second configuration information.

9. The apparatus of claim 1 , wherein the first configuration information includes one or more of the following:

a quantization scheme of phase coefficients;

a quantization scheme of sub-band amplitude coefficients; or

a quantization scheme of wideband amplitude coefficients.

10. The apparatus of claim 1 , wherein the PMI corresponds to a set of coefficients including a first subset of non-zero amplitude coefficients and a second subset of zero amplitude coefficients, and wherein a number of coefficients in each of the first and second subsets is based on the second configuration information.

11. The apparatus of claim 1 , further comprising transceiver circuitry coupled to the one or more processors; and, one or more antennas coupled to the transceiver circuitry.

12. An apparatus comprising:

one or more processors configured to cause a base station (BS) operating in a cellular network to:

transmit, in a radio resource control (RRC) configuration message, first configuration information to configure determination of channel quality information (CQI), a rank indicator (RI), and a precoding matrix indicator (PMI) for channel state information (CSI) reporting by a user equipment (UE);

transmit second configuration information for transmission to the UE, the second configuration information to configure codebook parameters for a high spatial resolution codebook associated with the PMI; and

receive CSI from the UE, the CSI including the RI and the PMI, wherein the PMI is based on a precoding matrix determined based on the first configuration information and a number of coefficients in at least one coefficient vector for reporting the precoding matrix is configured utilizing the second configuration information.

13. The apparatus of claim 12 , wherein the second configuration information configures a maximum number of coefficients for a first transmission layer of a plurality of available transmission layers, and wherein the one or more processors further cause the BS to:

transmit third configuration information for transmission to the UE, the third configuration information configuring a maximum number of coefficients for a second transmission layer of the plurality of available transmission layers.

14. The apparatus of claim 13 , wherein the precoding matrix is determined further based on the second and third configuration information, wherein a number of coefficients for the first transmission layer is configured utilizing the second configuration information, and a number of coefficients for the second transmission layer is configured utilizing the third configuration information.

15. A user equipment (UE) comprising:

one or more memories storing program instructions; and

one or more processor coupled to the one or more memories, the instructions to configure the one or more processors for performing channel state information (CSI) reporting in a cellular network and to cause the UE to:

receive, in a radio resource control (RRC) configuration message, first configuration information to configure determination of channel quality information (CQI), a rank indicator (RI), and a precoding matrix indicator (PMI) for the CSI reporting;

receive second configuration information to configure codebook parameters for a high spatial resolution codebook associated with the PMI;

determine a precoding matrix based on the first configuration information, wherein a number of coefficients in at least one coefficient vector for reporting the precoding matrix is configured utilizing the second configuration information; and

transmit CSI for transmission to a base station, the CSI including the RI and the PMI associated with the determined precoding matrix.

16. The UE of claim 15 , wherein the PMI corresponds to a linear combination of mutually orthogonal discrete Fourier transform (DFT) beams.

17. The UE of claim 16 , wherein a number of the mutually orthogonal DFT beams is configured for respective ranks of a plurality of ranks based on the first configuration information.

18. The UE of claim 15 , wherein the second configuration information configures a maximum number of coefficients for a first transmission layer of a plurality of available transmission layers, and wherein executing the instructions further cause the UE to:

receive third configuration information configuring a maximum number of coefficients for a second transmission layer of the plurality of available transmission layers.

19. The UE of claim 18 , wherein executing the instructions further cause the UE to:

determine the precoding matrix further based on the second and third configuration information, wherein a number of coefficients for the first transmission layer is configured utilizing the second configuration information, and a number of coefficients for the second transmission layer is configured utilizing the third configuration information.

20. The UE of claim 15 , wherein second configuration information configures a maximum number of coefficients for reporting per transmission layer of a plurality of available transmission layers.