Error Rate Performance of MIMO FSO Systems Using SC-QAM Signals and APD Receiver over Log-normal Fading Channels ☆

This paper theoretically study the error rate performance of multiple-input multiple-output (MIMO) free space optical (FSO) systems employing subcarrier quadrature-amplitude modulated (QAM) signals and avalanche photodiode (APD) in weak atmospheric turbulence channels modeled by the Log-normal fading distribution. An analytical expression of average symbol error rate (ASER) is analytical derived taking into account the impact of the turbulence induced scintillation, link lengths, MIMO configurations, APD receiver thermal noise and shot noise. The analysis demonstrates that impressive systems’ performance is achieved when the APD gain values are selected in the range from 5 to 10