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Probabilistically shaped polar-coded MIMO-FSO communication systems with spatially correlated fading
Optics Express
|October 15, 2022
Summary
Probabilistically shaped polar-coded multiple-input multiple-output free-space optical (MIMO-FSO) systems enhance transmission. Shaped systems show superior achievable information rates and bit error performance, even outperforming larger uniform systems in turbulent channels.
Area of Science:
- Optical Communications
- Information Theory
- Wireless Communication Systems
Background:
- Free-space optical (FSO) communication systems offer high bandwidth potential but face challenges from atmospheric turbulence.
- Multiple-input multiple-output (MIMO) techniques and polar coding are employed to enhance the reliability and efficiency of FSO links.
- Spatially correlated (SC) fading can impact the performance of MIMO-FSO systems.
Purpose of the Study:
- To investigate the performance of probabilistically shaped polar-coded MIMO-FSO communication systems.
- To evaluate the impact of spatially correlated (SC) fading on these systems.
- To determine the optimal number of shaping bits for improved transmission performance.
Main Methods:
- Utilizing a novel shaping-polar encoder capable of generating three distinct distribution shapes.
- Evaluating the achievable information rate (AIR) for MIMO-FSO systems with and without SC fading.
- Analyzing bit error rate (BER) performance under various atmospheric turbulence conditions.
Main Results:
- Non-pairwise distributions were found to be more effective for turbulence channels.
- Shaped 4x4 MIMO-FSO systems demonstrated superior AIR compared to uniform 4x5 systems in low SNR regions over strong turbulence.
- Significant shaping gains (over 15 dB) were achieved in BER compared to uniform single-input single-output polar-coded systems.
Conclusions:
- Probabilistically shaped polar-coded MIMO-FSO systems offer substantial performance improvements over conventional systems.
- The proposed shaping technique enhances system robustness against atmospheric turbulence and SC fading.
- Shaped 4x4 systems provide competitive performance, comparable to larger uniform MIMO systems, with improved spectral efficiency.
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