FPGA-Based adaptive digital predistortion for radio-over-fiber links

Even though the application of radio-over-fiber links is widely used in wireless communication, nonlinear distortion limits their dynamic range. In this paper, a hardware implementation of an adaptive digital predistortion system for ROF links is described. This complex gain predistortion technique is used to compensate amplitude and phase distortion. The system is adapted from the difference between the input and the output base band signals. Furthermore, this system supports continuous tracking of the modifications and drifts in the link characteristic. Details of the ADP system, the overall design of the hardware system, and field programmable gate arrays implementation of the system are presented and the results of the implementation discussed.