BER Analysis of IM/DD FSO System with APD Receiver Over Gamma-Gamma Turbulence

Abstract

In this paper, the bit-error rate (BER) performance of intensitymodulated with direct detection (IM/DD) free space optical (FSO) system using the on-off keying (OOK) and avalanche photodiode (APD) receiver is analyzed. The intensity fluctuations of the received optical signal are modeled by gammagamma distribution, while both zero and nonzero inner scale models are observed. The total receiver noise includes APD shot noise and thermal noise. The BER expression is theoretically derived and numerical results are presented. The results illustrate the BER dependence on the turbulence strength, propagation path length, APD gain and noise temperature.