A Simplified Main Beam Linearization Angle Widening Method for 5G Massive MIMO Systems With OTA Feedback

In this paper, we propose a simplified main beam linearization angle widening method for a 5G massive MIMO mm-wave transmitter with over-the-air feedback. The proposed method simplifies the original linearization angle widening method of the beam-oriented digital predistortion (BO-DPD). In linearization, multiple feedback signals measured from different target angles near the main beam are not directly combined into a large-scale basis function matrix, but combined into a small matrix by accumulating, and then the BO-DPD method is employed. Therefore, the scale of the basis function matrix can be greatly reduced when solving DPD coefficients by the least square method. The method is verified on a
$\mathbf{1}\times \mathbf{64}$
large-scale mm-wave transmitter, which is excited by a 5G new radio (NR) FR2 signal with the carrier frequency of 26 GHz and the band-width of 100 MHz. The experimental results show that compared with the linearization angle widening method of BO-DPD, the simplified method can achieve similar DPD results, but the computational complexity is lower.