On Secure Communications for FSO Systems Over Generalized Turbulence Channels

With the continued development of optical wireless communications, the security performance of free space optical (FSO) communications is the most crucial aspect that should receive significant attention. Despite the fact that FSO communications are considered more secure than radio frequency systems, their link performance degrades due to some environmental factors such as atmospheric turbulence, fog, and non-zero boresight pointing errors. The combined effect of these factors on the secrecy performance of FSO communication systems over the generalized Malaga- M fading channel is investigated in this paper. This work assumes a more realistic eavesdropping scenario in which both legitimate and unauthorized receivers are located on the same receiving plane. Secrecy outage probability and strictly positive secrecy capacity are expressed in exact closed-form expressions in this work. The results show that the FSO system has acceptable secrecy performance in moderate and light fog, with potential reach distances ranging from hundreds of meters to a few kilometers. Monte-Carlo simulations are used to verify the numerical results.