Nonlinear neural network with phase normalization for base-band modelling of radio-frequency non-linearities

An apparatus, comprising:

• at least one processor;
• and
• at least one non-transitory memory configured to store instructions that, when executed with the at least one processor, cause the apparatus to perform:
• obtaining a data communication signal comprising a plurality of complex-valued input samples;
• capturing, from the plurality of complex-valued input samples, a current sample and a set of delayed samples;
• generating a phase-normalized input signal based on normalizing phase of the current sample and the set of delayed samples with a normalization term, wherein the normalization term is common for the current sample and the set of delayed samples;
• providing the phase-normalized input signal to a neural network, the neural network configured to mitigate non-linearity of a data communication chain and to output a complex-valued output sample for the plurality of complex-valued input samples;
• and
• denormalizing phase of the complex-valued output sample with a denormalization term, the denormalization term configured to restore phase of the data communication signal;
• wherein the normalizing phase is based on multiplication of the current sample and the delayed samples with the normalization term, wherein the denormalizing phase is based on multiplication of the complex-valued output sample with the denormalization term, and wherein the denormalization term comprises a complex conjugate of the normalization term.