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.

中文翻译：

---

大气湍流通道上非视距紫外线通信系统的空间分集技术

紫外线信号的丰富散射实现了非视距室外无线连接，并消除了自由空间光链路的视距要求。除了散射损耗外，紫外线信号还会遭受大气湍流引起的衰落。空间衰落是一种强大的衰落缓解技术，它已在无线射频和红外网络的背景下得到了广泛的研究。在这项研究中，考虑了非视距紫外线通信链路的空间分集技术。特别地，推导了多输入单输出（MISO），单输入多输出（SIMO）和多输入多输出（MIMO）非视距紫外线通信系统。单输入单输出（SISO）链路的BER性能也作为基准。推导的准确性通过蒙特卡洛模拟得到证实。结果表明，与SISO相比，空间分集方案的性能有了显着提高。作者进一步研究了空间相关性对具有空间多样性的非视距紫外线链路性能的影响。他们证明，空间相关性会显着降低性能，并且孔径之间的有效分隔对于实现最大分集增益至关重要。作者进一步研究了空间相关性对具有空间多样性的非视距紫外线链路性能的影响。他们证明，空间相关性会显着降低性能，并且孔径之间的有效分隔对于实现最大分集增益至关重要。作者进一步研究了空间相关性对具有空间多样性的非视距紫外线链路性能的影响。他们证明，空间相关性会显着降低性能，并且孔径之间的有效分隔对于实现最大分集增益至关重要。