Modeling RF Frontend of Active Integrated Antenna Array for Direct-to-Device Communications

Direct-to-device communications represent a notable area of growth for emerging Low Earth Orbit mega-constellations, as also highlighted in upcoming standardization initiatives. For such applications, direct radiating arrays show strong potential in the user link segment. Considering the stringent requirements for both spectral and power efficiencies, the performance of the distributed power amplification must be carefully evaluated. The large number of radiating elements makes the use of commercial simulation software impractical due to excessive computation time and convergence issues. In this article, we propose the integration of a hardware-oriented behavioral model for active phased arrays within a realistic direct-to-device scenario. We analyze the effects of non-linearities on the error vector magnitude at the users. Our study spans from the generation of 5G signals for satellite direct-to-device applications to their reception by user equipment, with a focus on the physical layer of large active phased array systems.