Experimental performance evaluation of non-line-of-sight ultraviolet communication systems

摘要

Motivated by rapid advances in solar blind ultraviolet (UV) light emitting diodes (LEDs), filters and photomultiplier tubes (PMTs), together with unique UV atmospheric propagation characteristics, a non-line-of-sight (NLOS) UV communication test-bed has been recently built and utilized for extensive experimental evaluation of performance of NLOS UV links in outdoor environments. Towards this end, key link components are first characterized and their limitations are identified. The tradeoffs among communication range, received number of photons, and bit-error-rate are revealed via field measurement results. Wavelength diversity is achieved by utilizing combinations of sources and detectors centered at different wavelengths in the solar blind band. It is demonstrated that signals can be reliably transmitted to their destinations of dozens of meters away through an NLOS channel. Although all reported results in this paper are based on open field experiments, it is found that reflections from surrounding objects such as trees and buildings can enhance the received signal strength, up to an order of magnitude increase in the received number of photons in some cases, thus significantly improving link performance.