Performance assessment of OFDM-based and OWDM-based Radio-over-Fiber systems in the presence of phase noise

In this paper the impact of a Radio-over-Fiber (RoF) optical subsystem on the sensitivity to the phase noise of an Orthogonal Frequency Division Multiplexing (OFDM) system using Discrete Fourier Transform (DFT) and Discrete Wavelet Transform (DWT) are evaluated and compared by computer simulation. The study investigates the effect of phase jitter on the system Bit Error Rate (BER) of the DFT/DWT-based OFDM for different modulation schemes in the presence of optical sub-system's nonlinearities in AWGN channel. The results of this research show that at low phase noise levels, some DWT-based schemes outperform DFT-based scheme, however they achieve the same performance at high phase noise levels. It is understood that RoF systems are less robust against phase noise compared to their linear counterparts. Also, increasing modulation order leads to an increase in sensitivity to phase noise regardless of the Multi-Carrier (MC) scheme used. Furthermore, the performance of some wavelets are slightly different, especially at low σ (the variance of the phase noise) values. Finally, QAM signals are more robust against phase noise compared to PSK signals in RoF systems.