Circular Polarization Shift Keying With Homodyne Coherent Detection In Gamma-Gamma Atmospheric Turbulence Channel

We propose a communication system of Circular Polarization Shift Keying (CPolSK) with homodyne coherent detection in free-space optical (FSO) communication with Gamma-Gamma atmospheric turbulence channel. The system need no polarization coordinate alignment, thus the complexity is reduced. Meanwhile, we derived the closed bit error rate (BER) expression of the system compared with the coherent on-off keying (OOK) system. Simulation results show that CPolSK with homodyne system is highly insensitive to the phase noise and BER performance is greatly promoted compared to OOK modulation, the signal-to-noise ratio (SNR) of receiving is reduced about 8dB when the system has the same BER performance under same conditions.