Port selection codebook enhancements for spatial and frequency domain density reciprocity

An apparatus configured for wireless communication, the apparatus comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor,
• wherein the at least one processor is configured:
• to receive, by a user equipment (UE), a channel state information (CSI) report configuration from a serving base station, wherein the CSI report configuration includes configuration of a plurality of CSI-reference signal (CSI-RS) port groups, each CSI-RS port group of the plurality of CSI-RS port groups including one or more CSI-RS ports, and wherein each CSI-RS port group is associated with one or more codebook subset restrictions (CBSR), the one or more CBSR including a CBSR for wideband frequency domain basis linear combination coefficient and a CBSR for a plurality of subband frequency domain bases linear combination coefficients;
• to determine, by the UE, one or more linear combination coefficients based on channel measurements of one or more CSI-RS port groups of the plurality of CSI-RS port groups, wherein the one or more linear combination coefficients are determined according to the one or more CBSR associated with the one or more CSI-RS port groups;
• and
• to report, by the UE, a CSI report to the serving base station, wherein the CSI report includes the one or more linear combination coefficients.

An apparatus configured for wireless communication, the apparatus comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor,
• wherein the at least one processor is configured:
• to generate, by a base station, a channel state information (CSI) report configuration for one or more served user equipments (UEs), wherein the CSI report configuration includes configuration of a plurality of CSI-reference signal (CSI-RS) port groups, each CSI-RS port group of the plurality of CSI-RS port groups including one or more CSI-RS ports, and wherein each CSI-RS port group is associated with one or more codebook subset restrictions (CBSR), the one or more CBSR including a CBSR for wideband frequency domain basis linear combination coefficient and a CBSR for a plurality of subband frequency domain bases linear combination coefficients;
• to receive, by the base station, a CSI report including one or more linear combination coefficients from the one or more served UEs based on channel measurements of one or more CSI-RS port groups of the plurality of CSI-RS port groups determined according to the one or more CBSR associated with the one or more CSI-RS port groups;
• to determine, by the base station, a hybrid CSI-RS codebook using the plurality of CSI-RS port groups and the one or more linear combination coefficients;
• and
• to transmit, by the base station, downlink data encoded with a precoding matrix selected from the hybrid CSI-RS codebook.