Methods and Apparatus for Linearization of a Power Amplifier Output

A method for linearization of a power amplifier (PA) output comprising:

• training a neural network (NN) of an NN-based Digital Pre-Distortion (DPD) unit using a feedback loop, wherein the feedback loop comprises:
• obtaining a training pre-distorter signal, a training PA signal and a training DPD unit signal, wherein the training pre-distorter signal, the training PA signal, and the training DPD unit signal are all associated with each other;
• calculating a training signal length using the training PA signal and the training DPD unit signal;
• calculating a time shifted signal using the training PA signal and the training signal length;
• calculating a phase mismatch between the time shifted signal and the training DPD unit signal;
• calculating a compensated pre-distorter signal using the training pre-distorter signal and the phase mismatch;
• and
• training the NN of the NN-based DPD unit using the compensated pre-distorter signal;
• wherein the method further comprises:
• inputting a signal to be amplified into the NN-based DPD unit;
• obtaining a DPD unit signal from the NN-based DPD unit;
• inputting the DPD unit signal into the PA;
• and
• obtaining an amplified signal from the PA.

A network apparatus, the network apparatus comprising processing circuitry and a non-transitory machine-readable medium storing instructions for execution by the processing circuitry, whereby the network apparatus is configured to:

• train a neural network (NN) of an NN-based Digital Pre-Distortion (DPD) unit using a feedback loop, wherein the feedback loop comprises:
• obtaining a training pre-distorter signal, a training PA signal and a training DPD unit signal, wherein the training pre-distorter signal, the training PA signal, and the training DPD unit signal are all associated with each other;
• calculating a training signal length using the training PA signal and the training DPD unit signal;
• calculating a time shifted signal using the training PA signal and the training signal length;
• calculating a phase mismatch between the time shifted signal and the training DPD unit signal;
• calculating a compensated pre-distorter signal using the training pre-distorter signal and the phase mismatch;
• and
• training the NN of the NN-based DPD unit using the compensated pre-distorter signal;
• wherein the network apparatus is further configured to:
• input a signal to be amplified into the NN-based DPD unit;
• obtain a DPD unit signal from the NN-based DPD unit;
• input the DPD unit signal into the PA;
• and
• obtain an amplified signal from the PA.