In this paper, a novel single-scatter path loss model is presented for non-line-of-sight (NLOS) ultraviolet (UV) channels. This model is developed based on the spherical coordinate system and extends the previous restricted models to handle the general noncoplanar case of arbitrarily pointing transmitter and receiver. Numerical examples on path loss are illustrated for various system geometries. These results are verified with a Monte Carlo (MC) model, demonstrating the validity of this model.

A universal non-line-of-sight (NLOS) ultraviolet single-scatter propagation model in noncoplanar geometry is proposed to generalize an existing restricted analytical model. This generalized model considers that the transmitter and the receiver cone axes lie in the same plane or different planes, where they can be pointed in arbitrary directions. The model is verified by extensive simulations, showing that the proposed model is consistent with the original NLOS single-scatter propagation model and the Monte Carlo model. The path loss performance is further investigated in terms of different noncoplanar geometric settings and path loss dependence is also analyzed for different factors, including scattering volume size, relative position between the scattering volume and the transceiver, and radiation intensity of the transmitter.

Non-line-of-sight ultraviolet propagation models have been developed for both coplanar and noncoplanar geometries. Based on an exact integral-form single-scatter model, this Letter proposes an approximate closed-form model for tractable analysis applicable to noncoplanar geometries with a narrow transmitter beam or receiver field of view. Numerical results on path loss are presented for various system geometries. These results are verified with the integral-form model and a previous approximate model, showing our model agrees well with the former and outperforms the latter.

Non-line-of-sight (NLOS) ultraviolet communication (UVC) uses the atmosphere as a propagation medium. In previous literature, various scatter propagation models have been derived based on the premise that atmospheric turbulence was ignored and the atmosphere was considered as a turbid medium, also called random scatterers. In this Letter, a NLOS single-scatter propagation model is proposed to describe the singly scattered radiation in a turbulent medium, also called a random continuum, such as the clear atmosphere. The model is established based on the relationship between the scattered power and the characteristics of the random turbulent medium. The scattering cross section is further investigated in terms of different correlation distances and wavelengths. The received power dependence for NLOS UVC is also analyzed for different factors, including refractive-index structure parameter and transceiver range.

In non-line-of-sight (NLOS) UV communication links using intensity modulation with direct detection, atmospheric turbulence-induced intensity fluctuations can significantly impair link performance. To mitigate turbulence-induced fading and, therefore, to improve the bit error rate (BER) performance, spatial diversity reception can be used over NLOS UV links, which involves the deployment of multiple receivers. The maximum-likelihood (ML) spatial diversity scheme is derived for spatially correlated NLOS UV links, and the influence of various fading correlation at different receivers on the BER performance is investigated. For the dual-receiver case, ML diversity detection is compared with equal gain combining and optimal combining schemes under different turbulence intensity conditions.