Link Budget Analysis for Inter-Satellite FSO Links with Comprehensive Pointing-Error Models

In this paper, we investigate the impact of the jitter due to misalignment between the transmitter and the receiver on the link budget in free-space optical (FSO) inter-satellite link (ISL) in Low-Earth-Orbit (LEO) satellite communication systems. We first classify six different pointing-error radial displacement models based on the diverse characteristics of boresight and jitter. Then using the relationship between pointing-error radial displacement and pointing error, we derive the corresponding probability density functions (PDFs). Next, we determine a realistic ISL distance by applying a specific SpaceX Starlink constellation model. Finally, utilizing these results, we analyze the ISL link budget using closed-form and Monte Carlo simulation methods over varying jitter levels under a given power constraint.