Satellite Digital Channelizer Beamforming with Predistorted High-Power Amplifier
Technical Report,04 Apr 2018,05 Nov 2019
Wichita State University Wichita United States
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This report studies for the first time a digital channelizer combined with a digital high-power amplifier HPA and a digital predistorter PD for future satellite onboard processing. 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 memoryless HPA. Hence, no overlapping in the time domain among MAU samples occurs, so undesirable intermodulation IM products can be avoided, whereas an analog HPA operating near a saturation point causes significant IM product degradation at the HPA output when a sum of MAU sub-band signals are fed into it. 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 for each MAU sub-band signal sample stream to direct to each individual target terminal. Finally, this report verifies the performance of the proposed digital channelizer combined with the digital PD and HPA by presenting both the analytical and simulation bit error rate BER results, thereby concluding that the overall degradation is negligible.
- Radiofrequency Wave Propagation
- Electrical and Electronic Equipment
- Radio Communications