  Accurate fading characterization and channel capacity determination are of
paramount importance in both conventional and emerging communication systems.
The present work addresses the nonlinearity of the propagation medium and its
effects on the channel capacity. Such fading conditions are first characterized
using information theoretic measures, namely, Shannon entropy, cross entropy
and relative entropy. The corresponding effects on the channel capacity with
and without power adaptation are then analyzed. Closed-form expressions are
derived and validated through comparisons with respective results from computer
simulations. It is shown that the effects of fading nonlinearities are
significantly larger than those of fading parameters such as the scattered-wave
power ratio, and the correlation coefficient between the in-phase and
quadrature components in each cluster of multipath components.
