Digital Predistortion for mm-Wave MIMO Phased Arrays

In this work, we consider the application of digital predistortion for MIMO mm-wave RF beamforming-based subarrays. We propose a single-input single-output (SISO) DPD model as a linearization technique to mitigate the nonlinear behaviour exhibited by the power amplifiers in mm-wave phased arrays. This model incorporates mutual coupling between the antenna elements. This particular SISO-based model is obtained by transforming a dual-input-based model that accounts for the load-impedance mismatch between the antenna elements. Our proposed SISO-based DPD model can be considered a possible replacement of complex dual-input-based modelling approaches. We provide simulation results of two different array beamforming configurations: Single user beamforming array system (A 64-element antenna array) and multi-user beamforming array system (4 x 64 elements antenna array).