CSI reporting based on linear combination codebook

The present invention relates to a method performed by a user equipment (UE1) for generating a channel state information, CSI, report in a wireless communication system, comprising receiving from a network node (gNB2), a CSI report configuration information including at least one parameter, D, for indicating a first basis set of D basis vectors used for constructing for each transmission layer a precoding vector or matrix for a rank set, wherein the first basis set is a subset of a basis set comprising N3 basis vectors, each vector of size N3 × 1, wherein D < N3, and N3 is a number of subbands, identifying a precoding vector matrix for each transmission layer based on the first basis set, a second basis set comprising P basis vectors, and a number of combining coefficients for combining selected vectors from the first and second basis sets, generating a CSI report based on the CSI report configuration information for a rank indication value, RI, or v of the rank set, wherein the CSI report comprises for each transmission layer or subsets of transmission layers or all transmission layers an indication of a subset of P' selected basis vectors from the second basis set, wherein P' < P or P' ≤ P, and for each of the P' basis vectors an indication of D' < D or D' ≤ D selected basis vectors from the first basis set, and transmitting the CSI report to the network node (gNB2).