Uneven Frequency-Domain Basis Allocation for Type II CSI Enhancements

A method performed by a wireless device, the method comprising:

• estimating a channel state of a downlink channel;
• and
• transmitting a channel state information (CSI) report for the downlink channel based on the channel state, the CSI report indicating a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component,
• wherein the method further comprises:
• determining, for each spatial-domain component of the spatial-domain components, which one or more frequency-domain components from a set of candidate frequency-domain components to be associated with that spatial-domain component;
• determining a linear combination coefficient for each combination of spatial-domain component and associated frequency-domain component;
• and
• including an indication of the determined linear combination coefficients as part of the CSI report,
• wherein the CSI report comprises an indication of the number of associated frequency-domain components for each of the spatial-domain components, and wherein the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components.

A method performed by a base station, the method comprising:

• receiving a channel state information (CSI) report for a downlink channel, the CSI report indicating a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the received CSI report includes an indication of a linear combination coefficient for each combination of spatial-domain component and associated frequency-domain component;
• and
• transmitting data to a wireless device according to precoding determined based at least in part on the CSI report,
• wherein the CSI report comprises an indication of the number of associated frequency-domain components for each of the spatial-domain components, and wherein the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components.

A wireless device comprising:

• power supply circuitry configured to supply power to the wireless device;
• and
• processing circuitry configured to cause the wireless device to:
• estimate a channel state of a downlink channel;
• and
• transmit a channel state information (CSI) report for the downlink channel based on the channel state, the CSI report indicating a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component,
• wherein the processing circuitry is further configured to cause the wireless device to:
• determine, for each of the spatial-domain components, which one or more frequency-domain components from a set of candidate frequency-domain components to be associated with that spatial-domain component;
• determine a linear combination coefficient for each combination of spatial-domain component and associated frequency-domain component;
• and
• include an indication of the determined linear combination coefficients as part of the CSI report,
• wherein the CSI report comprises an indication of the number of associated frequency-domain components for each of the spatial-domain components, and wherein the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components.

A base station comprising:

• power supply circuitry configured to supply power to the base station;
• and
• processing circuitry configured to cause the base station to:
• receive a channel state information (CSI) report for a downlink channel, the CSI report indicating a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the received CSI report includes an indication of a linear combination coefficient for each combination of spatial-domain component and associated frequency-domain component;
• and
• transmit data to a wireless device according to precoding determined based at least in part on the CSI report,
• wherein the CSI report comprises an indication of the number of associated frequency-domain components for each of the spatial-domain components, and wherein the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components.