1. A method, comprising: receiving a signal comprising first data precoded on the basis of a first codebook entry of a codebook at a receiver, wherein the codebook comprises at least one further codebook entry; averaging a set of matrices to obtain a mean matrix using an averaging unit of the receiver, wherein each matrix of the set of matrices is determined on the basis of a respective other codebook entry of the at least one further codebook entry; and determining a covariance matrix on the basis of the mean matrix.