Influence of Frequency Mapping on Intermodulation Distortion in an SOA-Based Optical Fronthaul C-RAN Architecture for 5G Communications

In this paper, three orthogonal frequency division multiplexing (OFDM) bands of 400 MHz are successfully transmitted over 20 km of single-mode fiber (SMF). The framework is that of a fifth generation (5G) centralized radio access network (C-RAN) architecture including semiconductor optical amplifier (SOA), using analog intermediate frequency signal over fiber (AIFoF) technology. An error vector magnitude (EVM) enhancement is observed by adopting an optimized intermediate frequency (IF) configuration that minimizes the system nonlinearities by avoiding second-order intermodulation distortions (IMD2) caused by the optical modulator, SOA and photodiode association.