New results in secrecy analysis of mixed RF/FSO cooperative relaying networks

Abstract In this research work, the secrecy performance of a mixed radio frequency (RF)/ free space optical (FSO) cooperative relaying system has been analyzed. The statistics on the RF link has been modeled using the Nakagami- m model. The FSO link has been considered to be affected by joint impact of atmospheric turbulence and pointing error which has been assumed to undergo Malaga ( M ) distribution. The security of cooperative relaying system is considered to be impacted due to presence of eavesdropper in the vicinity of the destination node. The relay to eavesdropper link undergoes turbulence and pointing error modeled using the M distribution. More importantly, the source and relay nodes have been assumed to operate non-ideally which has been quantified as aggregated hardware impairment. For the system under test, closed-form expression has been derived for the average secrecy rate (ASR) in terms of extended generalized bivariate Fox H-function (EGBFHF). Furthermore, considering large values for the average signal-to-noise (SNR) on both RF and FSO links, asymptotic expressions for ASR have been derived in terms of elementary functions. The obtained secrecy rate results of the mixed RF/FSO relaying scheme suggest that the presence of eavesdropper and hardware impairment at the relay impacts the ASR offered by the system significantly.