Rich scattering of the signals in the ultraviolet (UV) band of electromagnetic spectrum enables non-line-of-sight (NLOS) outdoor wireless connectivity. It eliminates the line-of-sight requirement of the links which ar...
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Rich scattering of the signals in the ultraviolet (UV) band of electromagnetic spectrum enables non-line-of-sight (NLOS) outdoor wireless connectivity. It eliminates the line-of-sight requirement of the links which are using the signals in the infra-red band. Besides scattering losses, UV signals also suffer from atmospheric turbulence-induced fading. The turbulent atmospheric channel causes fluctuations in the received signal intensity of a NLOS ultraviolet (NLOS-UV) link, resulting in power loss and the performance degradation at the receiver. In this study, spatial diversity techniques are investigated as an appealing fading mitigation technique for NLOS-UV systems over atmospheric turbulence channels. In particular, the outage probabilities of multiple-input-single-output (MISO), single-input-multiple-output (SIMO), and multiple-input-multiple-output (MIMO) links are studied, and the outage performances are investigated for different system configurations. Closed-form expressions are derived for the outage probability of MISO, SIMO, and MIMO systems, and the accuracy of the derivations is confirmed through Monte Carlo simulations. The outage probability of single-input-single-output link is also derived as a benchmark. The results demonstrate significant performance improvements through deployment and proper configuration of MIMO systems in NLOS-UV communication links.
Rich scattering of ultraviolet signals enables the non-line-of-sight outdoor wireless connectivity and eliminates the line-of-sight requirement of free-space optical links. Besides scattering losses, ultraviolet signa...
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Rich scattering of ultraviolet signals enables the non-line-of-sight outdoor wireless connectivity and eliminates the line-of-sight requirement of free-space optical links. Besides scattering losses, ultraviolet signals also suffer from the atmospheric turbulence-induced fading. One of the strong fading mitigation techniques is the spatial diversity, which has been extensively studied in the context of wireless radio frequency and infrared networks. In this study, spatial diversity techniques for non-line-of-sight ultraviolet communication links are considered. In particular, multiple-input-single-output (MISO), single-input-multiple-output (SIMO), and multiple-input-multiple-output (MIMO) non-line-of-sight ultraviolet communication systems are derived. The BER performance of the single-input-single-output (SISO) link is also derived as a benchmark. The accuracy of the derivations is confirmed through Monte Carlo simulations. The results demonstrate the significant performance improvements in spatial diversity schemes over SISO counterparts. The authors further investigate the effect of spatial correlation on the performance of non-line-of-sight ultraviolet links with spatial diversity. They demonstrate that the spatial correlation degrades the performance significantly, and efficient separation between apertures is crucial to achieve the maximum diversity gain.
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