Power Penalty Analysis of IM-DD Free Space Optical Communication Channel in the Presence of Turbulence

In this paper, power penalty analysis is carried out to investigate the effect of free space optical channel turbulence on the Intensity Modulation-Direct Detection (IM-DD) FSO communication system. The effect of atmospheric turbulence is modeled using the Exponentiated Weibull (EW) distribution. It is found that the performance of IM-DD FSO system is highly degraded due to the turbulence impact and suffers from significant power penalties. Further, it is noticed that the effect of turbulence induced intensity distortion can be significantly reduced by increasing the average aperture diameter. For example, in the presence of strong turbulence, the power penalty at a BER of 10-9 and a link distance of 3 km and using an aperture diameter of 15 cm is 15.19 dB. This could be reduced to 8.74 dB when the aperture diameter is increased to 25 cm. Further, as expected, as the link distance increases, the contour plot power penalty curves increase significantly, and the gap between consecutive contours becomes remarkably larger.