Differential channel estimation and sounding associated with reconfigurable intelligent surfaces

A wireless transmit/receive unit (WTRU) comprising:

• a processor configured to:
• receive configuration information associated with a reconfigurable intelligent surface (RIS), wherein the configuration information indicates a first set of RIS parameters associated with a first RIS configuration and a second set of RIS parameters associated with a second RIS configuration;
• receive a first channel state information-reference signal (CSI-RS) associated with the first set of RIS parameters;
• receive a second CSI-RS associated with the second set of RIS parameters;
• determine, based on the first CSI-RS and the second CSI-RS, a differential CSI measurement associated with a base station (BS)-RIS-WTRU channel associated with the WTRU;
• and
• send a CSI report indicating the differential CSI measurement.

A method performed by a wireless transmit/receive unit (WTRU) comprising:

• receiving configuration information associated with a reconfigurable intelligent surface (RIS), wherein the configuration information indicates a first set of RIS parameters associated with a first RIS configuration and a second set of RIS parameters associated with a second RIS configuration;
• receiving a first channel state information-reference signal (CSI-RS) associated with the first set of RIS parameters;
• receiving a second CSI-RS associated with the second set of RIS parameters;
• determining, based on the first CSI-RS and the second CSI-RS, a differential CSI measurement associated with a base station (BS)-RIS-WTRU channel;
• and
• sending a CSI report indicating the differential CSI measurement.