Measurement of optical impairments in OFDM based radio-over-fiber communication systems

Radio-over-Fiber (RoF) technology allows radio frequency transmission directly over the fiber. Optical link employs laser, optical fiber and optical detector to transmit RF signal. RoF has an ability to carry signals for tens of kilometers, but this transmission is limited by optical impairments such as laser nonlinearity, fiber dispersion, and optical detector noises. In this paper, we study the effects of multimode fiber core refractive index profile, optical detector noises and atmospheric instability on the achievable performance of an OFDM based RoF link. The optical-signal-to-noise ratio (OSNR) and cumulative signal-to-noise ratio (SNRc) are used to evaluate the feasibility of the proposed scheme for a low-cost, reliable, robust, and high data rate fiber-wireless link. Thereafter, numerical results are generated for the downlink to illustrate the performance of the OFDM based RoF system.