Method and apparatus for reciprocity based CSI-RS transmission and reception

A base station (BS) comprising:

• a processor configured to:
• generate configuration information for at least one channel state information reference signal (CSI-RS) resource that comprises a number (PCSIRS) of ports CSI-RS (PCSIRS CSI-RS ports);
• and
• generate configuration information for channel state information (CSI) feedback that is based on a number (Q) of precoding dimensions (Q precoding dimensions),
• wherein:
• there is a mapping between the PCSIRS CSI-RS ports and the Q precoding dimensions, and
• PCSIRS≠Q;
• and
• a transceiver operably coupled to the processor, the transceiver configured to:
• transmit the configuration information for the at least one CSI-RS resource;
• transmit the configuration information for the CSI feedback;
• transmit the at least one CSI-RS resource from the PCSIRS CSI-RS ports;
• and
• receive, over an uplink (UL) channel, the CSI feedback;
• wherein:
• the CSI feedback is based on the Q precoding dimensions, and
• the Q precoding dimensions are based on the mapping and the PCSIRS CSI-RS ports.

A method for operating a user equipment (UE), the method comprising:

• receiving configuration information for at least one channel state information reference signal (CSI-RS) resource that comprises a number (PCSIRS) of CSI-RS ports (PCSIRS CSI-RS ports);
• and
• receiving configuration information for channel state information (CSI) feedback that is based on a number (Q) of precoding dimensions (Q precoding dimensions),
• wherein:
• there is a mapping between the PCSIRS CSI-RS ports and the Q precoding dimensions, and
• PCSIRS≠Q;
• measuring the PCSIRS CSI-RS ports;
• determining a measurement for the Q precoding dimensions based on the mapping and the measurement for the PCSIRS CSI-RS ports;
• determining a CSI feedback based on the measurement for the Q precoding dimensions;
• and
• transmitting, over an uplink (UL) channel, the determined CSI feedback.