FDM FSO communication system with coherent heterodyne optical receiver under strong turbulent condition

We provide an analytical approach to analysis the performances of FDM FSO communication system with coherent heterodyne optical receiver under strong turbulent condition which is modeled as gamma–gamma distribution. Analysis is carried out to find the bit error rate and channel capacity with RF subcarrier modulation taking into consideration the effect of strong atmospheric turbulence. Results are evaluated numerically in terms of average CNR, BER, channel capacity and power penalty suffered by the system due to the effect of turbulence at a given BER for several system parameters like turbulence variance, link distance, local oscillator power, etc. It is observed that at a data rate of 10 Gbps with number of subcarrier 32, the power penalty at a BER of 10 −9 is 12 dB for a link distance of 3.6 km and the performance improves gradually with increasing the number of RF subcarriers. It is also observed that, the overall performance improves with the improvement in both RF and optical local oscillator power.