Analytic and Simulative Modeling of RoF System with Intensity Modulation Including Fiber Dispersion Effect

Radio over fiber (RoF) network is integration of two networks named as wireless and optical fiber networks. The conversion of the light signal from electric signal at the transmitter is the most challenging task in the radio over fiber system. Radio over fiber transmission of double sideband (DSB) optical signal undergoes frequency-dependent signal fading due to fiber dispersion. In this paper, fiber dispersion effect on RF signal amplitude is theoretically analyzed while using intensity modulation. Numerical and simulation result indicates that the variation of relative RF signal amplitude with respect to depth of modulation and length of the fiber is sinusoidal in nature. Analysis shows the dependence of RF signal amplitude on the modulation index, radio frequency of RF signal, and the length of the optical fiber. It is seen that the RF signal fundamental amplitude which is free from the harmonic sidebands, suffers from the dispersion induced fading only but the variation of the RF signal harmonic amplitude which include the harmonic sidebands with second order as well as the harmonic sidebands with fourth order, has the cyclic property with respect to fading. This cyclic variation depends on modulation index and is due to the harmonic sidebands that are generated through the nonlinear response of the intensity modulation.