Methods and apparatuses for reducing feedback overhead

[0057] In the following, a detailed description of exemplary embodiments in several contexts is presented in conjunction with the drawings to enable an easier understanding of the solutions described herein.

[0058] As previously described, in the 3GPP NR system, two types of codebooks, namely Type 1 and Type 2 codebooks, have been standardized for CSI feedback supporting advanced MIMO operation.

[0059] This embodiment addresses the problem of how to efficiently quantize and report transformed combining coefficients in order to reduce CSI feedback overhead in communication networks using beamforming.

[0060] a. matrix Quantification and reporting of complex combination coefficients for

[0061] The previously proposed and repeated below in equation (3) is an overall precoder that can be written as

[0062]

[0063] in (3) Each complex coefficient in is associated with a specific delay (in the domain of the transform), since each DFT / DCT basis vector can model