Predictive adaptive optics optimal control for LEO communications in low elevation and strong scintillation...

Area of Science:

• Optical Engineering
• Communications Engineering
• Atmospheric Physics

Background:

• Free space optical communication (FSOC) offers advantages over radio frequency but suffers from atmospheric turbulence.
• Adaptive optics (AO) systems mitigate turbulence, but traditional integral controllers face limitations like time delay and instability in high scintillation.
• Predictive control algorithms show potential for improving FSOC coupling efficiency.

Purpose of the Study:

• To demonstrate and quantify the effectiveness of zonal-based linear quadratic Gaussian (LQG) regulators for FSOC.
• To evaluate LQG performance in challenging low elevation and high scintillation scenarios for LEO downlinks.
• To compare LQG regulators against traditional tuned integrators.

Main Methods:

• Simulation-based study incorporating Fresnel propagation, often neglected in prior research.
• Implementation of zonal-based LQG regulators for AO systems in FSOC.
• Consideration of phase oversampling and edge compensation model changes as LQG improvements.

Main Results:

• The best performing zonal-based LQG regulator improved mean coupling efficiency by 70% compared to a tuned integrator.
• LQG regulators demonstrated superior performance in high scintillation and low elevation scenarios.
• The inclusion of Fresnel propagation in the simulation provided a more realistic performance evaluation.

Conclusions:

• Zonal-based LQG regulators offer a significant improvement for FSOC AO systems, especially under adverse atmospheric conditions.
• Predictive control strategies like LQG are crucial for overcoming limitations of traditional controllers in FSOC.
• Further research into LQG improvements, such as phase oversampling, can enhance FSOC link reliability and performance.