A Bidirectional WDM-PON Free Space Optical (FSO) System for Fronthaul 5 G C-RAN Networks

High-speed cellular technologies require low-latency and high-capacity optical networks. The Centralized Radio Access Network (C-RAN) architecture offers a cost-effective solution for mobile network deployment. To maximize flexibility minimize deployment costs of fronthaul networks, we propose hybrid bidirectional C-RAN topology based on Wavelength Division Multiplexing (WDM) passive networks (PONs) free space communication (FSO). wavelength reuse scheme utilized here relies reflective semiconductor amplifiers (RSOAs) to reduce cost increase capacity. system was demonstrated 20 Gbps 16 $-$ quadrature amplitude modulation (16-QAM) intensity-modulated orthogonal frequency-division multiplexing (OFDM) downstream signals 5 On-off keying (OOK) upstream signals, respectively. A Gamma-Gamma channel model is used demonstrate signal transmission over an FSO link. bit error rate (BER) results indicate that the WDM-PON-FSO could achieve 320 km single-mode fiber (SMF) 700 m transmission.