Contour integral representation for generalized Marcum-Q function and its application to unified analysis of dual-branch selection diversity over correlated Nakagami-m fading channels

Using a circular contour integral representation for the generalized Marcum-Q function, Q_m(a,b), we derive a new closed-form formula for the moment generating function (MGF) of the output signal power of a dual-diversity selection combiner (SC) in bivariate Nakagami-m fading with positive integer fading severity index. This result involves only elementary functions and holds for any value of the ratio a/b in Q_m(a,b). As an aside, we show that previous trigonometric integral representations for Q_m(a,b) can be obtained directly from this contour integral. The MGF is used to unify the evaluation of average error performance and outage performance of a dual-branch SC for coherent, differentially coherent and noncoherent communications systems