AF relay-assisted MIMO/FSO/QAM systems in Gamma-Gamma fading channels

In this paper, the performance of amplify-and-forward (AF) relay-assisted multiple-input multiple-output free-space optical communication (MIMO/FSO) systems using sub-carrier intensity quadrature amplitude modulation (QAM) over Gamma-Gamma fading channels, which is represented for the case of strong atmospheric turbulence region, is studied. More specifically, an average symbol error rate (ASER) analytical expression for the AF relay-assisted MIMO/FSO/QAM systems is derived taking into account the strong atmospheric turbulence channel and the number of AF relaying stations with fixed gains. Numerical results qualitatively analyze the influence of the number of relaying stations, link distances, fixed gains and MIMO configurations on the performance of such systems.