EVOLUTION OF FREE SPACE OPTICAL SYSTEM BASED ON SUBCARRIER INTENSITY MODULATION OVER SOME DEGREE OF TURBULENT

Abstract

The use of Binary Phase Shift Keying (BPSK) Subcarrier Intensity Modulation (SIM) in a Gamma-gamma turbulent atmospheric channel was used to study the behavior of Free-Space Optical (FSO) communication system. Subcarrier Intensity Modulation was used to obviate a requirement for an adaptive threshold detector. At the receiver, direct detection was used and each subcarrier is subsequently demodulated clearly. The optimal Maximum Ratio Combining (MRC), the Equal Gain Combining (EGC), and the Selection Combining (SC) was used to combine the received signals linearly. Combining diversity made the effect of irradiance fading less severe. The Bit Error Rate (BER) equations are gotten by putting both the Additive White Gaussian Noise and Gamma-gamma intensity fluctuations into consideration. The simulation results show that at any given Bit Error Rate (BER), the performance of MRC was exceptional compared to the other two techniques. The overall results also put forward the model capability of reducing atmospheric turbulence especially for the 5G wireless network in the terrestrial link.