Nonlinear amplification of clipped-filtered multicarrier signals

This paper considers nonlinear amplification of multicarrier signals that were preliminary clipped and filtered in order to reduce envelope fluctuations. While reducing envelope fluctuations, clipping introduces an additional nonlinearity which causes similar interference effects as nonlinear amplification does. Filtering attenuates the out-of-band interference, but results in some peak regrowth. In this paper, the aim is to establish how much the clipping-filtering technique can improve the performance of OFDM systems when the amplifier is nonlinear. The scheme with repeated clipping-filtering is also studied. We observe some performance improvement in the case of single clipping with the clipping ratio value equal to 7 dB in AWGN and Rayleigh fading channels. Nonlinearity degrades the BER performance less in a fading environment compared with that in AWGN. Consequently, the TD performance is better in a Rayleigh fading channel.