Clipping and predistortion for compensation of OFDM-Radio over Fiber link distortion

A combined clipping/predistortion scheme is proposed and demonstrated for the distortion compensation of OFDM-Radio over Fiber links at baseband. In this scheme, a memory-polynomial-based predistorter and a simple amplitude clipping method are used. No specific filter is used after the clipping function, which reduces the implementation complexity. Experimental results confirm that the proposed approach gives significantly better performance compared to the digital predistortion (without clipping) approach for highly distorted OFDM RoF links. Changes in the OFDM signal´s PAPR through the RoF link are analysed for the predistortion schemes with and without clipping. As a result of this, a way of optimizing the performance of the clipping/predistortion approach is proposed.