Orbital Angular Momentum-Based Inter-Satellite Optical Communication Systems: Channel Modeling and Performance Analysis

Orbital angular momentum (OAM) multiplexing presents a promising method for improving the channel capacity of inter-satellite optical communication (ISOC) systems in satellite formation flying. However, the performance of OAM-based ISOC systems is highly susceptible to pointing errors induced by perturbations and platform vibrations in inter-satellite links. This study develops and analyzes an OAM-based ISOC system for satellite formation flying missions and investigates the impact of these pointing errors on communication performance. First, the probability density function (PDF) of inter-satellite radial displacement induced by perturbations is derived. Then, the PDFs of OAM mode purity and crosstalk are established while accounting for the effects of perturbations and platform vibrations. Finally, the expressions for average bit error rate and ergodic capacity are derived to characterize the influence of pointing errors on OAM-based ISOC performance. Simulation results offer insights into OAM-based ISOC performance under various perturbation and vibration conditions, revealing the impact of pointing errors across different OAM multiplexing schemes. Additionally, a conventional ISOC system employing Gaussian beams is simulated as a baseline to emphasize the advantages of OAM beams. These findings reveal the impact mechanisms of pointing errors, under the influence of orbital altitude and initial inter-satellite distance, on the communication performance of OAM-based ISOC systems.