UC Riverside

This thesis studies modeling of non-line-of-sight (NLOS) ultraviolet (UV) scattering channels and the corresponding communication link performance. The research focuses on the channel impulse response and path loss models based on extensive field measurements and theoretical characterization. In NLOS UV scattering environments, transmitted signals suffer from severe atmospheric attenuation and fading before arriving at a receiver, such as absorption, scattering, and turbulence. The thesis is devoted to development of analytical and experimental models to characterize NLOS UV communication channels.

The author conducts comprehensive channel measurements for short communication ranges up to a few hundred meters and proposes an empirical path loss model. Meanwhile, an algorithm is developed to simulate the NLOS UV channel impulse response and path loss based on photons stochastic migration in the atmosphere. Effects of atmosphere conditions on single scattering and multiple scattering are investigated. An empirical curve-fitting model is developed to simplify the modeling work. Monte Carlo simulations provide good channel prediction for field tests in many scenarios. Then short range communication link performance is studied based on the theoretical models, and limitations by power and channel bandwidth are examined. Link budget results are also extended to long range communication links up to 5 kilometers. In this case, atmosphere turbulence becomes pronounced, and thus the intensity fluctuation at the receiver is mathematically modeled. These modeling results can provide insight into the performance tradeoffs and algorithm design for practical NLOS UV communication systems.