Introducing an Optimal Modulation Constellation, Resistant to Atmospheric Turbulence

One of the communication platforms commonly used in C4I backing layers is the free space optical  communication platform. In this paper, the modulation of polarization is proposed to strengthen the free space optical communication platform against atmospheric perturbations. In this method, instead of using conventional modulation methods such as amplitude, phase or frequency modulations, the polarization states are modulated on the optical beam. Conventional modulation methods are highly sensitive to turbulence fluctuations. Polarization modulation is highly resistant to the phase noise of laser beams and it maintains the polarization states on a long path in free space. Generally, binary polarization modulation, works better than conventional modulations by about 2 dB or more. More specifically, in this paper, different polarization modulation constellations in Poincaré are plotted and their probability of error is evaluated in different positions. Finally, the optimal states of the constellation are extracted by simulations.