Higher order asymptotics of mutual information for nonlinear channels with nongaussian noise

In this paper, we are interested in finding the higher order asymptotics of the mutual information I(X; εf(X) + Z] up to terms of order o(εⁿ) as ε → 0 where n is a given integer, n ≥ 2. The higher order asymptotics for such mutual information in the simplest channel model V. V. Prelov (1989) was found in V. V. Prelov (1988) for the case where the noise Z is Gaussian and in V. V. Prelov (1989) if Z is nonGaussian. In the recent paper V. V. Prelov, S. Verdu (2002), the second order asymptotics of the mutual information was found for multidimensional complex-valued nonlinear channels similar to V. V. Prelov (1988) with a Gaussian noise Z.