  The performance of equal gain combining reception at free-space optical
communication systems is analytically studied and evaluated. We consider the
case when the total received signal undergoes independent and not necessarily
identically distributed channel fading, modeled by the versatile mixture-Gamma
distribution. Also, the misalignment-induced fading due to the presence of
pointing errors is jointly considered in the enclosed analysis. New closed-form
expressions in terms of finite sum series of the Meijer's $G$-function are
derived regarding some key performance metrics of the considered system;
namely, the scintillation index, outage probability, and average bit-error
rate. Based on these results, some useful outcomes are manifested, such as the
system diversity order, the crucial role of diversity branches, and the impact
of composite channel fading/pointing error effect onto the system performance.
