Effects of noise and distortion on performance of OFDM millimeter-wave RoF systems

In this paper, we theoretically investigate the effects of noise and nonlinear distortion on the performance of orthogonal frequency-division multiplexing (OFDM) signal carried by millimeter-wave radio over fiber (RoF) systems. Various noise components are considered in this paper including shot noise, thermal noise and relative intensity noise. In addition, we take into account the effect of nonlinear distortion caused by two non-linearity devices that are Mach-Zehnder modulator (MZM) and photodetector. Numerical results show that the effect of noise can be effectively mitigated by increasing the optical transmitted power or the modulation index of MZM. However, when modulation index is larger than a specific value, the nonlinear distortion is likely dominant over the noise, which results in degradation of the system performance. Optimum values of modulation index for some special cases are shown in this paper.