Quantum Key Distribution Over Free Space Optical Satellite Links in the 6G Era
Year: 2026
Type: conference-paper
Abstract: Satellite-based free-space optical links can act as time-varying optical wireless interconnects that distribute quantum resources across space-terrestrial infrastructures, complementing the 6G vision of integrated non-terrestrial networks. Among quantum communication services, Quantum Key Distribution (QKD) is the most mature and is therefore adopted as an illustrative use case. This paper develops an attenuation-centric framework for satellite QKD based on weak-coherentpulse BB84. The considered system model links orbital geometry and optical terminal parameters to an equivalent channel transmissivity, which governs detection statistics, quantum bit error rate (QBER), and secret key generation through secrecy bounds. We derive the secret-fraction cutoff behavior with respect to channel attenuation and show how it induces time-dependent secret key rates during satellite overpasses. Numerical results using orbital data and representative parameters from the 'Micius' mission show that the minimum slant range over the onemonth observation window spans approximately 400-2400 km; approximately 34% of passes have minimum slant ranges below 900 km, and favorable passes yield secret key rates on the order of a few kbps. The proposed modeling approach provides a link-level building block for future network-level studies, where scheduling and routing of quantum-secured services can be informed by predicted key generation windows over satellite optical interconnects.
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7204147519