Spatial-Diversity Imaging Receivers for Non-Line-of-Sight Solar-Blind UV Communications

Optical wireless links in the solar-blind ultraviolet (SB-UV) band transmit data without the need of a line-of-sight through the use of atmospheric scattering. These links have a host of advantages including security, covertness and ease of deployment, however, they inherently suffer large path loss and delay spread due to the underlying atmospheric scattering process. This paper considers the use of spatial degrees of freedom at the receiver to improve the information rates of SB-UV channels. Classical scattering link models are extended to provide both temporal and spatial arrival information for scattered photons. A spatio-temporal channel model is developed for SB-UV channels using multi-element imaging receivers. Spatial diversity techniques for delay compensation and detector noise suppression are presented and information rates under equally likely signalling are computed to contrast their performance. In the particular cases considered, the information rate using a spatial diversity receiver is improved approximately 50% over single element receiver channels.