Optimum modulation for radio-over-fiber links transmitting OFDM NQAM RF signals

The OFDM modulation format is widely used in several wireless applications because it is robust against multi-path distortions in the radio channel. The OFDM signals are usually transmitted over an optical link to the wireless network. However OFDM is sensitive to the channel nonlinearities. The nonlinearity of this type of modulation can cause distortion and this way limitation on the optical transmission. In this paper we present investigations on the limitations by simulations and experiments with the result of conditions for optimum operation.