Performance Analysis of QAM-SIM FSO Systems over Gamma-Gamma Turbulence Channels

In this paper, we investigate the effects of the pointing errors on the performance of a Free-Space Optical (FSO) communication system using subcarrier intensity modulation (SIM) with general-order rectangular quadrature amplitude modulation (QAM) and operating over Gamma-Gamma (GG) turbulence channels. We derive novel, exact closed-form expression for the average symbol error probability (ASEP) of the considered system in terms of the Fox H function. Using the derived analytical results, we investigate the combined effects of turbulence-induced fading and pointing errors on the performance of the SIM-QAM FOS communication system. Numerical and computer simulation results are presented in order to verify the accuracy of the proposed mathematical analysis.

کلیدواژه ها:

free-space optical communications ، quadrature amplitude modulation (QAM) ، Gamma-Gamma distribution ، Pointing error ، Average symbol error probability