AbstractRadio over fiber is a technology in which the light signals at the central station are modulated by a radio frequency signal, and by using the optical fiber it is transmitted to base stations. The data stream being sent is separated into subcarrier frequencies by the technique of orthogonal frequency division multiplexing. The orthogonality between the sub-carriers is provided by FFT modulation, which avoids the demodulators from accepting other frequencies. It is possible to transmit high-data rate signals over short and long distance by implementing orthogonal frequency division multiplexing with radio over fiber system along with the optical fiber. This enhances the system with more coverage area, and without increasing the cost of the system it provides the flexibility. The proposed work is to investigate the performance analysis of single side band orthogonal frequency division multiplexing in radio over fiber system with external and direct modulations using spectral analysers and constellation visualizers. The Mach-Zender modulator is proposed for external modulation, the vertical cavity surface emitting laser is used in direct modulation. The simulations were carried out by using Optisystem Software version 15.0 with global parameters for both intensity modulation schemes.