A general method of coding over expansions is proposed, which allows one to
reduce the highly non-trivial problem of coding over continuous channels to much
simpler discrete ones. More specifically, the focus is on the additive
exponential noise (AEN) channel, for which the (binary) expansion of the
(exponential) noise random variable is considered. It is shown that each of the
random variables in the expansion corresponds to independent Bernoulli random
variables (each having a mean given by a function of the corresponding level
number and the mean of the underlying exponential random variable). 
This way, each of the expansion level (of the underlying channel) corresponds
to a binary symmetric channel, and the coding problem is reduced to coding over
these parallel channels.