  A comprehensive novel design is proposed for the free-space optical (FSO)
communication system by hybridizing circular polarization division multiplexing
(CPDM) with coherent optical orthogonal frequency division multiplexing
(CO-OFDM) and its performance is investigated realistically under diverse
turbulent weather conditions of Bangladesh. Here we consider Gamma-Gamma (G-G)
distribution for the turbulent FSO channel model. Moreover, the proposed scheme
presents an excellent performance since CPDM technique not only maximizes the
link capacity of FSO system but also enhances the spectral efficiency (SE) of
the system. Besides, multipath-fading, which is appeared during the FSO
transmission, is significantly mitigated by OFDM modulation. The outcomes from
simulation confirm the advantages of the proposed hybrid scheme and also it can
serve as a reference for the FSO application even in the turbulent weather
conditions. Performance analysis of the proposed model is described in terms of
optical power spectrum (OPS), optical signal to noise ratio (OSNR), bit error
rate (BER), Q factor, constellation diagrams, and eye diagrams.
