Closed-Form Error Probability of Blind Detection for Free Space Optical Systems

Atmospheric turbulence is a practical obstacle in deployment of free space optical (FSO) communications. Due to its ease of implementation, on-off keying (OOK) is a widely-adopted modulation technique for intensity modulation with direct detection (IM/DD) in optical communications. For optimal signal detection, the receiver needs to know the instantaneous channel fading coefficient to detect OOK symbols. In this paper, to reduce the effect of atmospheric turbulence, we employ blind detection to estimate the channel and to adjust the detection threshold. Since Monte Carlo analysis requires long simulation time, we derive a closed-form expression for the bit error probability of IM/DD systems. Numerical results are provided to validate the accuracy of derived analytical expressions.