EGC Reception for FSO Systems Under Mixture-Gamma Fading Channels and Pointing Errors

摘要

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