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 (PS), versus signal power launched to the fiber (PTX), 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.