Smaller sub-band size for PMI than for CQI

1. A method performed by a wireless device for transmitting channel state information, CSI, feedback using a multi-beam precoder codebook, the method comprising:

receiving a configuration for a sub-band channel quality indicator, CQI, granularity and a sub-band precoding matrix indicator, PMI, granularity for the wireless device, wherein the sub-band PMI granularity corresponds to a first sub-band size and the sub-band CQI granularity corresponds to a second sub-band size, wherein the first sub-band size is smaller than the second sub-band size; and

transmitting the CSI feedback to a base station, wherein the CSI feedback is in accordance with the sub-band CQI granularity and the sub-band PMI granularity, wherein the CSI feedback indicates a linear combination of precoder vectors for each of a plurality of frequency sub-bands having the first sub-band size, wherein the coefficients for the precoder vectors in the linear combinations of precoder vectors are parameterized in the frequency-domain as a linear combination of a set of basis vectors and a set of coefficients for the basis vectors in the linear combination of the set of basis vectors.

2. The method of claim 1 , wherein the precoder vectors are discrete Fourier transform, DFT, precoder vectors.

3. The method of claim 1 , wherein the CSI feedback is transmitted using a new radio, NR, Type II multi-beam precoder codebook.

4. The method of claim 1 , wherein the CSI feedback is of new radio, NR, enhanced Type II.

5. The method of claim 1 , wherein the second sub-band size is an integer multiple of the first sub-band size.

6. The method of claim 1 , wherein the sub-band CQI granularity configuration is obtained from a subbandSize radio resource control parameter in a CSI-ReportConfig.

7. The method of claim 1 , wherein the sub-band PMI granularity is obtained from a CSI-ReportConfig using a subbandPMI-Size parameter.

8. A method performed by a base station for receiving channel state information, CSI, feedback using a multi-beam precoder codebook, the method comprising:

receiving the CSI feedback from a wireless device according to a sub-band channel quality indicator, CQI, granularity and a sub-band precoding matrix indicator, PMI, granularity, wherein the sub-band PMI granularity corresponds to a first sub-band size and the sub-band CQI granularity corresponds to a second sub-band size, wherein the first sub-band size is smaller than the second sub-band size, wherein the CSI feedback indicates a linear combination of precoder vectors for each of a plurality of frequency sub-bands having the first sub-band size, wherein the coefficients for the precoder vectors in the linear combinations of precoder vectors are parameterized in the frequency-domain as a linear combination of a set of basis vectors and a set of coefficients for the basis vectors in the linear combination of the set of basis vectors.

9. The method of claim 8 , further comprising:

determining the sub-band CQI granularity;

determining the sub-band PMI granularity; and

configuring the wireless device with the sub-band CQI granularity and the sub-band PMI granularity.

10. The method of claim 8 , wherein the precoder vectors are discrete Fourier transform, DFT, precoder vectors, wherein the CSI feedback is received using a new radio, NR, Type II multi-beam precoder codebook, and wherein the CSI feedback is of new radio, NR, enhanced Type II.

11. A wireless device for transmitting channel state information, CSI, feedback using a multi-beam precoder codebook, the wireless device comprising:

a receiver;

a transmitter; and

processing circuitry coupled to the receiver and the transmitter, wherein the processing circuitry is configured to cause the wireless device to:

receive a configuration for a sub-band channel quality indicator, CQI, granularity and a sub-band precoding matrix indicator, PMI, granularity for the wireless device, wherein the sub-band PMI granularity corresponds to a first sub-band size and the sub-band CQI granularity corresponds to a second sub-band size, wherein the first sub-band size is smaller than the second sub-band size; and

transmit the CSI feedback to a base station, wherein the CSI feedback is in accordance with the configured sub-band CQI granularity and the sub-band PMI granularity, wherein the CSI feedback indicates a linear combination of precoder vectors for each of a plurality of frequency sub-bands having the first sub-band size, wherein the coefficients for the precoder vectors in the linear combinations of precoder vectors are parameterized in the frequency-domain as a linear combination of a set of basis vectors and a set of coefficients for the basis vectors in the linear combination of the set of basis vectors.

12. The wireless device of claim 11 , wherein the precoder vectors are discrete Fourier transform, DFT, precoder vectors.

13. The wireless device of claim 11 , wherein the CSI feedback is transmitted using a new radio, NR, Type II codebook.

14. The wireless device claim 11 , wherein the CSI feedback is of new radio, NR, enhanced Type II.

15. The wireless device of claim 11 , wherein the second sub-band size is an integer multiple of the first sub-band size.

16. The wireless device of claim 15 , wherein the processing circuitry is configured to cause the wireless device to obtain the sub-band CQI granularity configuration from a subbandSize radio resource control parameter in a CSI-ReportConfig.

17. The wireless device of claim 11 , wherein the processing circuitry is configured to cause the wireless device to obtain the sub-band PMI granularity from a CSI-ReportConfig using a subbandPMI-Size parameter.

18. A base station for receiving channel state information, CSI, feedback using a multi-beam precoder codebook, the base station comprising:

a receiver;

a transmitter; and

processing circuitry coupled to the receiver and the transmitter, wherein the processing circuitry is configured to cause the base station to:

receive the CSI feedback from a wireless device according to a sub-band channel quality indicator, CQI, granularity and a sub-band precoding matrix indicator, PMI, granularity, wherein the sub-band PMI granularity corresponds to a first sub-band size and the sub-band CQI granularity corresponds to a second sub-band size, wherein the first sub-band size is smaller than the second sub-band size, wherein the CSI feedback indicates a linear combination of precoder vectors for each of a plurality of frequency sub-bands having the first sub-band size, wherein the coefficients for the precoder vectors in the linear combinations of precoder vectors are parameterized in the frequency-domain as a linear combination of a set of basis vectors and a set of coefficients for the basis vectors in the linear combination of the set of basis vectors.

19. The base station of claim 18 , wherein the processing circuitry is further configured to cause the base station to:

determine the sub-band CQI granularity;

determine the sub-band PMI granularity; and

configure the wireless device with the sub-band CQI granularity and the sub-band PMI granularity.

20. The base station of claim 18 , wherein the precoder vectors are discrete Fourier transform, DFT, precoder vectors, wherein the CSI feedback is received using a new radio, NR, Type II multi-beam precoder codebook, and wherein the CSI feedback is of new radio, NR, enhanced Type II.