  Cooperative communication has been shown to provide significant increase of
transmission reliability and network capacity while expanding coverage in
cellular networks.
  The present work is devoted to the investigation of the end-to-end
performance and power allocation of a maximum-ratio-combining based
regenerative multi-relay cooperative network over non-homogeneous scattering
environment, which is the case in realistic wireless communication scenarios.
Novel analytic expressions are derived for the end-to-end symbol-error-rate of
both $M-$ary Phase-Shift Keying and $M-$ary Quadrature Amplitude Modulation
over independent and non-identically distributed generalized fading channels.
The offered results are expressed in closed-form involving the Lauricella
function and can be readily evaluated with the aid of a proposed computational
algorithm. Simple expressions are also derived for the corresponding
symbol-error-rate at asymptotically high signal-to-noise ratios. The derived
expressions are corroborated with respective results from computer simulations
and are subsequently employed in formulating a power optimization problem that
enhances the system performance under total power constraints within the
multi-relay cooperative system. Furthermore, it is shown that optimum power
allocation provides substantial performance gains over equal power allocation,
particularly, when the source-relay and relay-destination paths are highly
unbalanced.
