E2E Physical Layer and Link Analysis for High-Throughput Satellite Optical Communication

Satellite optical communications will revolutionize global high-speed connectivity. In this paper, we carry out a comprehensive evaluation of end-to-end (E2E) Wavelength Division Multiplexing (WDM)-Free Space Optical Communication (FSOC) systems to establish high-performance Earth-GEO links using a semi-analytical tool. We present a novel method to accurately compute the divergence of a truncated and obscured beam, typical of Cassegrain telescopes; this model is instrumental to optimize the beam divergence with Pointing Error (PE) and beam wander. The effects of beam wander, scintillation, and PE are first individually investigated to derive the required margins for different outage probabilities (OPs), followed by an assessment of Adaptive Optics (AO) benefits and limitations. Furthermore, we comprehensively assess the uplink and downlink systems, exploiting for the first time an innovative and fully analytical closed-form expression to describe the combined three statistical effects. Finally, the full system analysis is carried out in the challenging scenario of strong turbulence, at various elevation angles and OP targets. By considering both coherent and non-coherent systems adopted from fiber communications, we determine the transmitter power and the maximum achievable throughput.