OFDM Signal Transmission by EPWM Transmitter in Nonlinear RoF Channel

Radio-over-Fiber (RoF) technology enables low-loss distribution of RF signals over optical fiber, which contributes much for spreading broadband wireless access services into in-building areas and outdoor dead-spots. However, current broadband wireless access systems employ OFDM schemes and suffer from nonlinear distortion of the RoF channel due to nonlinearity inherent in Electrical to Optical (E/O) conversion. In this paper, a new RoF transmission scheme employing Envelop Pulse-Width Modulation (EPWM) transmitter has been proposed to efficiently suppress the impact of RoF channel nonlinearity on OFDM signals. This idea is executed in a typical RoF channel that uses a Mach-Zehnder modulator as its E/O convertor. It is proved by both simulation and experiment that the EPWM-RoF scheme can achieve linear transmission of OFDM signal via nonlinear RoF channel.