Method and apparatus for enhancement on basis subset indication for two-codebook based CSI reporting

The present disclosure relates to methods and apparatuses (UE, network node or gNB) for CSI reporting. The method performed by a UE comprises: receiving (201) from the gNB, a radio signal via a MIMO channel, wherein the radio signal contains at least one DL-RS according to a DL-RS configuration; estimating (202) said MIMO channel based on said received at least one DL reference signal for configured subbands; calculating(203) a precoder matrix or a CSI matrix for a number of antenna ports of the gNB and configured subbands; the precoder matrix being based on a first codebook and on a second codebook and a set of combination coefficients for complex scaling/combining one or more of vectors selected from the first codebook and the second codebook; and reporting (204), to the gNB, a CSI feedback report and/or a PMI/RI, used to indicate the precoder matrix or the CSI matrix for the configured antenna ports and subbands.