Hybrid Low-Cost Predistortion Solutions for Next Generation Satellite Transponder Linearization

In military satellite communication (MILSATCOM), the downlink transmission signals suffer from nonlinear distortions caused by the high power amplifier (HPA) of the satellite transponder, which can be characterized as amplitude modulation-to-amplitude modulation (AM-AM), and amplitude modulation-to-phase modulation (AM-PM) effects. To solve this problem, Intelligent Fusion Technology, Inc. (IFT) has conducted fruitful research on HPA linearization by using both physical and machine learning predistortion (PD) modeling techniques. An excellent linearization performance was achieved in the presence of various jamming signals by using the proposed hybrid PD solution. To develop the on-ground PD with full-fledged functions, and make it a successful product for Air Force’s need, IFT and its partner propose to refine the proposed system architecture with hub hardware modification only, and the best modulation and coding (MODCOD) mode is selected accordingly at user terminals to linearize the HPA. The proposed physical and machine learning PD models will be further assessed and completed by taking more practical MILSATCOM conditions into account. IFT proposes to test the developed PD system on our software defined radio (SDR) SATCOM testbed, and implement it on field programmable gate array (FPGA). Finally, the developed PD system prototype will be integrated to the actual MILSATCOM system.