@Article{cmes.2026.084050,
AUTHOR = {Wibby Aldryani Astuti Praditasari, Hyejin Yoon, Seunghwan Yun, Changuk Jang, Okyeon Yi},
TITLE = {Security-Constrained Adaptive Control for Satellite QKD Systems under Feasibility-Aware Operation},
JOURNAL = {Computer Modeling in Engineering \& Sciences},
VOLUME = {},
YEAR = {},
NUMBER = {},
PAGES = {{pages}},
URL = {http://www.techscience.com/CMES/online/detail/28281},
ISSN = {1526-1506},
ABSTRACT = {Satellite-based Quantum Key Distribution (QKD) provides a foundation for achieving information-theoretic security in long-distance communication systems. In practical satellite-to-ground scenarios, however, dynamic channel conditions significantly affect key validity, availability, and the stability of rekeying processes at higher communication layers. This work proposes a feasibility-aware adaptive control framework that enforces operation only within conditions where secure key generation remains valid, thereby preventing the use of cryptographically unreliable keys. The control mechanism is formulated as a constrained decision process and implemented using a Deep Q-Network (DQN), which dynamically adjusts basis selection in response to time-varying channel conditions. Unlike conventional approaches that focus solely on performance optimization, the proposed framework explicitly incorporates feasibility constraints into the control objective, ensuring that adaptive behavior remains aligned with the underlying security requirements of QKD. The framework is evaluated using a satellite-to-ground analytical channel model with parameters derived from representative experimental studies, capturing the expected behavior under representative satellite QKD conditions. Results show that, within the valid operating region, the proposed approach improves key availability, reduces key depletion events, and stabilizes rekeying behavior. At the system level, this enables the VPN layer to maintain AES-256 encryption for approximately 85% of the communication duration under typical conditions, with peak performance reaching up to 97% under favorable channel realizations. These values represent averaged performance across simulation runs, with higher values observed under optimal channel conditions. Overall, the results demonstrate that feasibility-aware adaptive control enhances both performance and security consistency by preventing operation in non-valid regimes while maintaining stable key availability under dynamic channel conditions. This work establishes a practical connection between quantum-layer constraints and system-level security outcomes, supporting more reliable deployment of quantum-enabled communication systems.},
DOI = {10.32604/cmes.2026.084050}
}