Performance evaluation of OOK free-space optical transmission system with dynamic decision threshold and coherent detection

Transmission performance of free-space optical (FSO) communication is severely degraded by scintillation effect, which is a slow fading process. In this paper, we propose a dynamic decision threshold scheme to efficiently detect the bit stream. The decision threshold is varied in every sub-millisecond time slot. In addition, it is shown that coherent detection with 10dBm-local oscillator (LO) can make the BER performance better than 10^-3 under different atmospheric turbulence scenarios from weak to strong.