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Reliable equalization aided long-distance OFDM-FSO performance analysis over Gamma-Gamma turbulence with thermal and
R Balakrishnan1, S Senthilkumar2
1Department of Electronics and Communication Engineering, Kings College of Engineering, Punalkulam, pudhukottai, Tamil Nadu, 613303, India. rbala.krish2011@gmail.com.
Scientific Reports
|May 5, 2026
Summary
This study investigates Free Space Optical Orthogonal Frequency Division Multiplexing (FSO-OFDM) for inter-satellite links, analyzing performance under various disturbances. Zero forcing equalization enhances long-distance communication, showing promise for stable LEO/MEO links.
Area of Science:
- Optical Communications
- Wireless Networking
- Satellite Technology
Background:
- Free Space Optical Orthogonal Frequency Division Multiplexing (FSO-OFDM) is a key technology for next-generation wireless links.
- Inter-satellite communication in Low Earth Orbit/Medium Earth Orbit (LEO/MEO) faces challenges from thermal noise, background noise, and solar storms.
- The Gamma-Gamma (GG) channel model is used to simulate these atmospheric disturbances.
Purpose of the Study:
- To investigate the performance of FSO-OFDM systems in LEO/MEO inter-satellite communication.
- To analyze the impact of channel impairments like turbulence, noise, and solar storms on different modulation schemes (BPSK, QPSK, M-ary QAM).
- To evaluate the effectiveness of zero forcing equalization in improving link distance and reducing bit error rate (BER).
Main Methods:
- Simulated FSO-OFDM performance using a Gamma-Gamma channel model.
- Analyzed bit error rate (BER) for BPSK, QPSK, and M-ary QAM under weak and strong turbulence conditions.
- Employed zero forcing equalization techniques at the receiver to mitigate channel impairments.
- Examined transmission link lengths ranging from 1000 to 11000 meters.
Main Results:
- Lower-order PSK schemes (BPSK, QPSK) offer reliable performance up to 7000m.
- In weak turbulence, 256-QAM achieves high spectral efficiency with a BER of 10^-12 at 23 dB SNR.
- Under severe turbulence, BPSK is optimal up to 7000m, while 256-QAM is more efficient for distances up to 11000m (BER of 10^-6 at 27.5 dB SNR).
- The developed equalization framework significantly improves performance for long-range OFDM-FSO communication.
Conclusions:
- FSO-OFDM systems can achieve stable long-range communication in LEO/MEO inter-satellite links.
- Modulation scheme selection is crucial and depends on turbulence conditions and desired link distance.
- Zero forcing equalization is an effective technique for enhancing the robustness and reach of FSO-OFDM systems in challenging environments.
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