A 112 Gbps flexible fiber-free space optics convergent passive optical network system for broadcasting high-speed data traffic under different weather conditions

In this work, we propose, design, and investigate a flexible fiber-free space optics (FSO) convergent passive optical network (PON) system, capable of transporting 112 Gbps data by employing polarization division multiplexing (PDM) with 16-level quadrature amplitude modulated (QAM) signals. The proposed flexible fiber-FSO-PON system supports high splitting ratio and the system investigation is reported for 128, 256, 512, and 1024 optical wireless units (OWUs) at the receiver. Bit error rate (BER), error vector magnitude (EVM), and constellation plots of the signals at the OWUs are used as the metrics for performance evaluation. After a 50 km single mode optical fiber propagation, free space propagation range varying from 210 to 700 m is achieved depending on the external weather conditions with good BER performance(log (BER) ∼ - 2.46). To improve the signal performance under channel distortion, carrier phase estimation and frequency offset estimation algorithms are used at the OWUs. The proposed flexible fiber-FSO-PON system can support 1024 OWUs up to 700 m free space range under clear weather and increases to 1.1 km, 1.65 km, and 2.35 km for 512, 256, and 128 OWUs respectively.