On the study of the FSO link performance under controlled turbulence and fog atmospheric conditions

In this paper, the effect of turbulence and fog on the free space optical (FSO) communication systems for on-off-keying (OOK), pulse amplitude modulation (PAM) and subcarrier intensity modulation (SIM) based on binary phase shift keying (BPSK) is experimentally investigated. The experiment is carried out in a controlled laboratory environment where turbulence and fog could be generated in a dedicated FSO chamber. In comparison to 4-PAM signal, the BPSK and OOK-NRZ modulation signalling format are more robust against the fog and turbulence effects. In addition BPSK system is much less susceptible to the signal amplitude fluctuation due to turbulence compared to the other two modulation formats.