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Published on: March 20, 2017
Physics-informed adaptive transmission for coherent free-space optical communications: multi-dimensional
Optics Express
|August 14, 2026
Summary
This study introduces a new adaptive modulation and coding (AMC) method for free-space optical (FSO) communications. It improves performance in turbulent conditions by considering both signal strength and phase distortion.
Area of Science:
- Optical Communications
- Wireless Communication Systems
- Signal Processing
Background:
- Coherent free-space optical (FSO) systems face challenges from coupled amplitude fading and phase distortion, particularly under atmospheric turbulence.
- Traditional adaptive modulation and coding (AMC) methods, relying only on signal-to-noise ratio (SNR), are insufficient for mitigating phase distortion, leading to performance degradation (error floors).
Purpose of the Study:
- To develop a novel physics-informed AMC framework for coherent FSO communications.
- To enhance system resilience and efficiency by incorporating phase distortion metrics alongside SNR for adaptive control.
Main Methods:
- Extraction of scintillation index (σI²) and phase variance (σφ²) from pilot signals.
- Formation of a multi-dimensional channel state vector using extracted metrics and SNR.
- Implementation of phase-aware modulation selection with turbulence-adaptive thresholds to prevent high-order formats during severe phase distortion.
Main Results:
- Demonstrated suppression of error floors in simulated FSO links under strong turbulence.
- Achieved significant SNR gains (0.6-2.0 dB at BER 10⁻³) and improved effective spectral efficiency (32-59%).
- Approached channel capacity (80-88% of BICM capacity) with low decision processing latency (<22 µs).
Conclusions:
- The proposed physics-informed AMC framework effectively addresses phase distortion in coherent FSO systems.
- This approach enables robust and efficient optical wireless communication, suitable for real-time FPGA implementation.
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