Performance analysis of non-line-of-sight ultraviolet communications under periodic pulse jamming attack through...

The widespread adoption of ultraviolet communication (UVC) in unmanned aerial vehicles (UAVs) introduces new threats to ground-based non-line-of-sight (NLOS) UVC networks from aerial jammers using line-of-sight (LOS) links. This work theoretically investigates the performance of an on-off keying-based NLOS UVC system subjected to asynchronous and periodic jamming pulses. Specifically, a refined probability mass function is proposed to characterize the ratio of jamming duration within a slot of legitimate signal to the slot itself, under the assumption that the jamming pulse period is an integer multiple of the slot, or vice versa. Turbulence over the jamming link is considered and described by the log-normal distribution. A closed-form average bit-error rate expression is derived in terms of the Gauss-Legendre quadrature rule and further verified through extensive simulations. A one-kilometer outdoor transmission experiment using ultraviolet light-emitting diodes (LEDs) is carried out to validate the signal characteristics and adopted channel models of the jamming link. Results reveal that the maximum jamming range of the aerial jammers, benefiting from LOS links, significantly exceeds that of ground-based jammers, which rely on NLOS links. Stronger turbulence along the jamming link exacerbates the degradation of system performance. Moreover, even with imprecise alignment, aerial jammers can induce substantial jamming effects on legitimate NLOS UVC systems due to the wide beam of LEDs. Lastly, the findings highlight that adjusting the receiver's orientation to mitigate jamming effects must also maintain sufficiently low path loss with the legitimate transmitter. Neglecting this balance could jeopardize the reliability of the communication link. This study contributes to the secure design of NLOS UVC links.