Secure NLOS ultraviolet communication against active/passive eavesdropping attacks

The security issue in ultraviolet (UV) communication arises due to a light scattering phenomenon wherein a number of light beams emit and scatter in random directions when a light wave strikes an aerosol. This paper investigates the physical layer security in non-line-of-sight UV communication with the consideration that simultaneous scattered light beams are incident on the field of view of the receivers of both legitimate and active or passive eavesdropping users. The novel closed-form average secrecy capacity and secrecy outage probability expressions are derived for both active and passive eavesdropping scenarios. Furthermore, the security performance is investigated under the influence of atmospheric weak, moderate, and strong turbulence effects. The numerical results are validated through computer simulation analysis.