Effect of Quadrature Amplitude Modulation Variation on EDFA-Based Radio over Fiber Performance

Radio over Fiber (RoF) integrates wireless and optical fiber to provide high bandwidth and low loss communication. However, due to the distortion and chromatic dispersion issues in the RoF system, it is essential to employ modulation techniques and optical amplifiers to improve the performance. This study examines how Erbium-Doped Fiber Amplifiers (EDFAs) affect the performance of RoF systems that use several Quadrature Amplitude Modulation (QAM) schemes, such as 4-QAM, 8-QAM, 16-QAM, and 32-QAM, for transmission distances of up to 100 km. The experiments demonstrate that the RoF system with 4-QAM modulation provides better performance compared to 8-QAM, 16-QAM, and 32-QAM modulation methods, achieving a Q-factor above 6 and a BER below 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> when the RoF transmission link is 85 km-long, the longest between all the modulation schemes. Furthermore, the use of EDFA increases transmission distances by 5 km compared to when the EDFA is not used.