Analysis of outage probability of PPM-BPSK-SIM based FSO communication system using wavelength diversity

Free space optical communication (FSO) meets the enormous need for high bandwidth and high data rate systems. As a result, FSO has played a critical role in research, with the added benefit of providing large amounts of bandwidth at a low cost and without the need for a licence. However, due to atmospheric turbulence, the optical signal in free space suffers from irradiance and phase variations, which weakens the signal strength and the performance of communication systems over longer distances, which is impractical. To min-imise turbulence-induced fading, the paper proposed a hybrid modulation technique with wavelength diversity over a gamma-gamma (GG) distribution, namely pulse position modulation-binary phase shift keying-subcarrier intensity modulation (PPM-BPSK-SIM). For estimating the probability of a system outage, paper propose a closed form mathematical expression. Finally, the findings show that combining a hybrid modulation scheme with a wavelength diversity scheme enhances the FSO communication system performance.