  Motivated by the fact that full diversity order is achieved using the
"best-relay" selection technique, we consider opportunistic amplify-and-forward
and decode-and-forward relaying systems. We focus on the outage probability of
such a systems and then derive closed-form expressions for the outage
probability of these systems over independent but non-identical imperfect
Log-normal fading channels. We consider the error of channel estimation as a
Gaussian random variable. As a result the estimated channels distribution are
not Log-normal either as would be in the case of the Rayleigh fading channels.
This is exactly the reason why our simulation results do not exactly matched
with analytical results. However, this difference is negligible for a wide
variety of situations.
