Towards 5G: a 100-Gb/s probabilistic shaping-OFDM based fiber-FSO convergent system using polarization multiplexing scheme for 5G access fronthaul network

The cumulative demand for high-speed and proficient data communication systems poses substantial challenges, including dispersion, inter-symbol interference (ISI), and fading effects in fiber-free-space optics (FSO) convergent networks. To address these issues, we propose and analyze, for the first time, a 100 Gbps probabilistic shaping (PS)-orthogonal frequency division multiplexing (OFDM)-based fiber-FSO convergent transmission system for near-generation smart communication applications. The proposed system enables the successful transmission of 100 Gbps data ([10 Gbps/wavelength × 5 wavelengths = 50 Gbps] × 2 states of polarization) over an 80-km single-mode fiber (SMF) link and a 600-m FSO link. The integration of PS and OFDM scheme enhances spectral efficiency within limited system bandwidth and extends transmission distance by mitigating the impacts of dispersion, ISI, and fading. Experimental results demonstrate the effectiveness of the proposed architecture, achieving a forward error correction code rate of 9/10 and a normalized generalized mutual information threshold of ~ 0.92. These results confirm the capability of the system to support flexible data rates and long-distance transmissions while ensuring reliability and efficiency. This work contributes to advancing fiber-FSO convergent systems, with potential future applications in scalable and adaptive communication networks.