Satellite digital beamforming with digital channelizer and it's performance under predistorted high power amplifier

Abstract

This dissertation proposes for the rst time a simple combination of a digital channelizer and a digital predistorter (PD) to generate an output signal without intermodulation (IM) products even under a nonlinear memoryless high-power ampli er (HPA) saturation point. A digital channelizer, called a polyphaser, takes multiple access user (MAU) frequency-division (FD) sub-band signals, converts the multiple MAU sample streams into a single sample stream, and then feeds it into a digital PD followed by an HPA. The proposed digital PD can compensate almost perfectly for both phase and amplitude distortion caused by the HPAs nonlinearity. Then, individual digital beamforming (BF) is applied after the HPA in order for each MAU sub-band signal sample stream to direct to each individual target terminal. Finally, this dissertation veri es the performance of the proposed digital channelizer combined with the digital PD under a Rician fading channel environment by showing negligible bit error rate (BER) degradation.