  The present paper is devoted to the evaluation of energy detection based
spectrum sensing over different multipath fading and shadowing conditions. This
is realized by means of a unified and versatile approach that is based on the
particularly flexible mixture gamma distribution. To this end, novel analytic
expressions are firstly derived for the probability of detection over MG fading
channels for the conventional single-channel communication scenario. These
expressions are subsequently employed in deriving closed-form expressions for
the case of square-law combining and square-law selection diversity methods.
The validity of the offered expressions is verified through comparisons with
results from respective computer simulations. Furthermore, they are employed in
analyzing the performance of energy detection over multipath fading, shadowing
and composite fading conditions, which provides useful insighs on the
performance and design of future cognitive radio based communication systems.
