Channel-Matrix Dependent Step Size for Iterative Precoding Matrix Calculation

A channel matrix representing characteristics of a multi-path channel between a transmitter device (210) equipped with multiple transmitter antennas (211, 212, 213, 214, 215) and at least one receiver device (220, 230, 240) equipped with one or more receiver antennas (221, 222, 231, 232, 241, 242). The channel matrix is organized in one or more channel vectors each associated with a corresponding one of the one or more receiver antennas (221, 222, 231, 232, 241, 242). An iterative optimization algorithm is applied to determine a precoding matrix from the channel matrix. At least one step size of the iterative optimization algorithm is set depending on a vector norm of at least one of the channel vectors. Multi-antenna transmission by the transmitter device (210) is then controlled based on the determined precoding matrix.