Second-order statistical properties of nonlinearly distorted phase-shift keyed (PSK) signals

In wireless communication systems operation of the amplifiers near saturation is often required for efficiency reasons, resulting in a nonlinearly distorted signal at the amplifier output. A popular model for the corresponding baseband equivalent nonlinear channel is a truncated Volterra series. By exploiting the bandpass nature of the channel and the statistical properties of phase-shift keyed signals, we show that the different terms in the Volterra series are white and uncorrelated with each other. This result is useful when considering blind equalization approaches for this class of systems.