Invisible Light Communications: Ultraviolet Enabling Robust High-Rate Underwater Communications

Underwater communication is a new frontier of telecommunications, supporting several applications, from glider control to sensor network management and allowing data fusion in what has been recently named the Internet of Underwater Things implemented via acoustic or optical communications. These two technologies show limitations concerning the available communication bandwidth and/or coverage, with the former being suitable for long-range low-rate links and the latter performing broadband transmissions over a few tens of meters in dark water conditions. Such drawbacks can be overcome by ultraviolet wireless technology, which cannot cover the range of acoustic transmissions but can achieve a more convenient trade-off between data rate and transmission range than visible light transmission during daytime. The gain obtained by ultraviolet with respect to visible light communication can be highlighted under different conditions. In some propagation scenarios, UV allows the detection with a signal-to-interference ratio that is at least 4/5 dB higher than that of VLC and a spectral efficiency improvement of 1/2 b/s/Hz.