Methods for reducing overhead of nr type ii channel state information feedback using angle and delay reciprocity

A network node configured to communicate with a wireless device, WD, the network node comprising:

• processing circuitry configured to configure the WD with a channel state information, CSI, report setting, the CSI report setting including at least one of:
• a CSI reference signal, CSI-RS, resource with NCSI-RS CSI-RS ports for channel measurement, each of the NCSI-RS ports being associated with a pair of spatial domain, SD, and frequency domain, FD, vectors;
• a first subset of length N3 frequency domain, FD, basis vectors of a discrete Fourier transform, the first subset comprising N basis vectors, one of which is a direct current, DC, basis vector containing all ones, where 1<=N<=N3;
• and
• a number M of FD basis vectors of a second subset of M FD basis vectors, the second subset being determined by the WD from the first subset of FD basis vectors, one of the M FD basis vectors being the DC basis vector, where M<=N;
• and
• a radio interface in communication with the processing circuitry (68) and configured to:
• transmit a CSI-RS to the WD;
• request the WD to feedback a CSI based on a CSI-RS and according to the CSI report setting;
• and
• receive from the WD a CSI report comprising at least one of:
• an indication of a number of transmission layers;
• an indication of a selection by the WD of a subset of the NCSI-RS CSI-RS ports;
• an indication of a selection by the WD of M FD basis vectors out of the N FD basis vectors;
• an indication of a set of linear combination coefficients associated with the selected subset of the CSI-RS ports and the selected M frequency domain basis vectors per transmission layer;
• and
• an indication of a total number of non-zero linear combination coefficients associated with all the M frequency domain basis vectors.