Optimal Predistortion of Gaussian Inputs for Clipping Channels

Abs t rac t For a clipped channel with a Gaussian input, a predistortionlrestoration technique to reduce clipping-induced nonlinear distortion is proposed and analyzed. The input sig-nal is processed by a nonlinear predistorter circuit, reducing the probability of clipping. The receiver output signal passes through a restorer having the inverse transfer characteristic, which yields the original signal. For both one-sided and two-sided limiter channels, the optimal predistortion curves are determined analytically. A limiter channel with Gaussian input may be used to model clipping-induced nonlinear distortion in optical-fiber common antenna television (CATV) distribution systems using multiple intensity-modulated subcarriers. When applied to an amplitude-modulated vestigial-sideband (AM-VSB) CATV system, the optimal predistortion curves yield sensitivity improve-ments of 5.3 and 4.4 dB for one- and two-sided limiter channels, respectively. I