Distortion reducing precoding

An apparatus, comprising:

• at least one processor;
• and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:
• receive a signal to be transmitted via an array of antennas from a linear precoder, wherein the signal is processed by the linear precoder based on one or more input power criteria for power amplifiers of the array of antennas;
• apply a distortion reducing matrix to the processed signal, wherein the distortion reducing matrix is trained to reduce the distortion at each output of the power amplifiers based on minimizing an error signal corresponding to a difference between measured and calculated outputs of the power amplifiers after a coupling effect between the power amplifiers based on the applied matrices,
• and wherein the distortion reducing matrix is further trained based on minimizing an error signal corresponding to a difference between a measured total input power to the power amplifiers and a total input power provided to the power amplifiers at startup of the apparatus;
• and
• provide an output of the distortion reducing matrix to be used in digital pre-distortion processing of an input signal for the power amplifiers.