Multiangle Complexity-Reduced Digital Predistortion for 5G/6G Massive MIMO Beamforming Transmitters

This letter presents a multiangle digital predistortion (DPD) method for linearizing 5G/6G massive multiple-input–multiple-output (mMIMO) beamforming transmitters. The cascade structure composed of a main box and the subbox tuning network is applied to linearize the main beam and all power amplifiers (PAs). The main box is a proposed improved full basis-propagating selection (IFBPS) DPD model with low complexity and accurate modeling properties. The subbox tuning network can linearize the PAs by several heterogeneous DPDs corresponding to the clustering categories based on the threshold decision results. The measurements were carried out on the laboratory-made PAs based on a single-user two-stream and four-chain MIMO system. Compared with the state-of-the-art DPDs, the results show that the proposed method can improve linearization performance with lower complexity and keep the multiangle linearity of systems without updating the coefficients in real time.