Design and Experimental Validation of Digital Pre-distortion Techniques for mmWave OTA with Multiple Nonlinear Power Amplifiers

The millimeter-wave (mmWave) frequency band is used in the 5th generation wireless systems, in which the high frequency unavoidably causes rapid attenuation. Therefore, multiple millimeter-wave power amplifiers (PAs) are utilized to achieve power amplification and to extend transmission range. However, the nonlinear effect is induced after the increased input power. To compensate the nonlinear effect of PAs, the transmitted signal can be pre-compensated by the digital pre-distortion (DPD) technology. In this paper, we verify the application performance of mmWave over-the-air (OTA) nonlinear PAs with DPD compensation. The research and simulation results confirm that the nonlinear problem and signal distortion caused by the power amplifier can be reduced by the indirect-learning based DPD technology, thereby improving the spectrum efficiency.