Study on performance of Digitized Radio over Fiber (RoF) system using EDFA and Coherent receiver

In this paper, a calculating model of Digitized Radio over Fiber (RoF) system using EDFA amplifier and Coherent receiver is proposed. We then investigate Signal-to-Noise Ratio (SNR) in different parts of the system and establish SNRtotal equation at the output of RF signal recovery in three cases: Direct Detection, Coherent Detection and Combined EDFA-Coherent Detection. Next, we write and run MatLab-based program to draw graphs that show system performance such as BER, SNR versus signal power at receiver input (P_S), versus signal power launched to the fiber (P_TX), versus transmission length of the system (D). Then, the performance comparison of Direct Detection, Coherent Detection and Combined EDFA-Coherent Detection is carried on. At the same time, 8 different demodulation methods in Combined EDFA-Coherent Detection are investigated and presented on graphs. The comparison and numerical results show that thanks to using Combined EDFA-Coherent Detection in Digitized RoF system, the signal quality is enhanced remarkbly. Some suitable demodulation methods are also proposed for applications.