Performance Enhancement of OFDM-Based Hybrid Multiplexed Ro-FSO System Under Complex Rain Conditions
The radio over free-space optical (Ro-FSO) link serves as an effective and resilient solution for distributing radio frequency (RF) signals over turbulent and adverse weather conditions, using high-frequency optical carriers. This work proposes an architecture for a high-speed, spectral-efficient, a...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2025-01-01
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| Series: | International Journal of Optics |
| Online Access: | http://dx.doi.org/10.1155/ijo/3110227 |
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| Summary: | The radio over free-space optical (Ro-FSO) link serves as an effective and resilient solution for distributing radio frequency (RF) signals over turbulent and adverse weather conditions, using high-frequency optical carriers. This work proposes an architecture for a high-speed, spectral-efficient, and long-reach hybrid multiplexed Ro-FSO system that integrates orthogonal frequency division multiplexing (OFDM), mode division multiplexing (MDM), and dense wavelength division multiplexing techniques to mitigate channel fading and rain attenuation effects and improve the maximum link range with the least signal-to-noise ratio (SNR). At 20 Gb/s, 16-QAM-OFDM-encoded four distinct 40 GHz radio signals, each optically modulated by Hermite–Gaussian (HG) laser modes (HG00, HG01, HG03, and HG04), are transported over a 50 km free-space link using hybrid multiplexing. Furthermore, the proposed system performance is analyzed under turbulent channel Cn2=5×10−13m−2/3 for [0.15, 16, and 19.26} dB/km attenuation levels, which correspond to clear-sky and moderate and strong rain weather conditions. We perform the SNR, bit error rate (BER), link transmission range, and eye diagram comparative analysis for the decomposed and composite transmitted HG modes at the detector end. The obtained results demonstrate excellent performance compared with current research work as summarized in the result section. At an SNR of 20 dB and a BER of 10−7, the maximum 44.8 km link range is achieved by the HG00, mode in a clear-sky condition, whereas the least 4 km link range is offered by the HG03 mode under strong rain conditions. The total link improvement of 2 and 1.2 km is observed under moderate and strong rain conditions if the proposed system incorporates the OFDM block during the analysis. However, the performance is also evaluated under the three climatic conditions at BER of 10−6 and 10−7, which clearly reveals the minimum SNR requirement for the same quality of reception for the OFDM-included proposed system. |
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| ISSN: | 1687-9392 |