![]() This modulation uses the vectorial property of light waves and coding digital bits as different states of polarization, which can be well preserved in long FSO links, to effectively overcome the phase noise of the laser source and relatively improve the performance of the BER. ![]() Polarization shift keying (PolSK) has been proposed to partially alleviate the restrictions of atmospheric turbulence. This impairment, measured by the scintillation index ( SI) and phase noise, will severely reduce the beam quality, resulting in high error rates and greater probability of interrupted communication, seriously affecting the stability and reliability of the FSO communication system and significantly restricting further development of the FSO technology. However, the most significant problem is that FSO links suffer from random changes in the refractive index caused by variations in air temperature and pressure, , which lead directly to intensity scintillation and phase fluctuation. Recently, there has been a resurgence of research interest in free-space optical (FSO) communication for its advantages of greater bandwidth, higher data transmission rates, more compact equipment, faster link installation, lower power consumption and better security over radio frequency (RF) communications. This study provides reference material for further design of the CPolSK system. Furthermore, we demonstrate that controlling the circular polarization control error below 8° as well as the normalized threshold within 8 dB, 9 dB and 10 dB in turbulent scenarios from weak to strong levels can significantly reduce the probability of communication interruption occurring. This consequently adds to the demand for emissive power from the CPolSK system. The deterioration in BER performance, caused by intensity scintillation and phase fluctuation, is augmented by the power penalty conditioned by the circular polarization control error. Simulation results show that atmospheric turbulence and circular polarization control error have significant effects on the BER performance and interruption of communication in the CPolSK system. We derive closed form expressions of the bit error rate (BER) and outage probability for evaluating the BER performance and communication interruption in the Gamma–Gamma distributed channel model. Intensity scintillation and phase fluctuation induced in atmospheric turbulence, from weak to strong levels, are specifically researched with respect to circular polarization control error caused by the system design. ![]()
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