Aperture selection approaches for robust NLOS-UV communication in turbulent channels

Abstract

In this research, we investigate aperture selection schemes for non-line-of-sight ultraviolet communication systems operating in log-normal atmospheric turbulence channels. The proposed approaches involve the selection of a single transmit and/or receive aperture from a pool of $N$ transmit and/or $M$ receive apertures for communication, based on maximizing the signal-to-noise ratio along the corresponding optical path. To further improve the performance of non-line-of-sight ultraviolet links, we incorporate an optically pre-amplified PIN photo-detector at the receiver and an optical booster amplifier at the transmitter. We consider all noise sources, including those arising from amplified spontaneous emission due to optical amplifiers. We derive closed-form outage and bit-error-rate expressions and conduct diversity gain analyses to assess the performance. Monte Carlo simulations are employed to validate the accuracy of our derivations. The results reveal that selection diversity schemes offer full diversity gain and outperform multiple-input-multiple-output non-line-of-sight ultraviolet systems without aperture selection. Our study demonstrates the efficacy of aperture selection as well as optical amplifiers in enhancing the reliability and performance of non-line-of-sight ultraviolet communication systems in turbulent atmospheric conditions.