High-Order Asymptotics of the Mutual Information in Nonlinear Non-Gaussian-Noise Channels

Nonlinear channels with non-Gaussian noise where the transmitted signal is a random function of the input signal are considered. Under some assumptions on smoothness and the behavior of tails of the noise density function, higher-order asymptotics of the mutual information between the input and output signals in such channels is obtained, as the mean power of the input signal (or, equivalently, the signal-to-noise ratio) goes to zero.