Analysis of selection combining hybrid FSO/RF systems considering physical layer security and interference

This paper investigates the hybrid free-space optical (FSO)/radio-frequency (RF) communication system under the influence of non-cooperative target (NCT) which includes eavesdropping the legitimate transmitters and jamming the legitimate receivers. The FSO link and RF link are modeled by Málaga(M) distribution and Nakagami-m distribution respectively. Both yield excellent fit experimental data as unified fading model. Pointing error, which is an indispensable parameter of FSO link, is also considered. Selection combining technique is adopted at the receiver which does not need channel state information at the transmitter. The closed-form expressions for outage probability, average bit error and secrecy outage probability are derived and simulated in this paper. Furthermore, asymptotic performance of the hybrid RF/FSO system is analyzed. The results show that hybrid system shows superior performance than FSO links even if the radio frequency interference exists.