Performance Analysis of Visible and Ultraviolet Light Communications
Abstract
As the proliferation of wireless communication devices advances, there is an ever-increasing demand for a faster, more liable and environmentally friendly way to be connected. Coincidentally, highly efficient semiconductor lighting devices, such as light emitting diodes (LEDs), have also dominated most of the modern illumination application, and ultraviolet (UV) has attracted much attention as an alternative non-line-of-sight (NLOS) communication medium. This thesis is devoted to the performance analysis of visible and ultraviolet light communication.
About line-of-sight (LOS) communication link, the author described an overview of state-of-the-art visible light communication (VLC) technology. The author also conducted the performance analysis for a precoding design for a red, green and blue (RGB) LEDs under indoor communication link geometry and a beehive structure receiver which enables massive multiple-input-multiple-out (MIMO) via its spatial diversity. Moreover, a vehicular VLC’s communication channel analysis under exhaust fume effect is also characterized.
The thesis also provided the most comprehensive long-distance overland NLOS UV channel analysis and overwater UV NLOS channel field measurement. The result suggested the need for a modified multiple scattering Monte Carlo NLOS UV channel modeling based on empirical data. In overwater NLOS UV scattering environment, the author examined the unique communication link configurations via numerous simulations from previous reported multiple scattering Monte Carlo (MC) channel model augmented with relevant overwater parameters. Comprehensive channel measurement data has been collected and analyzed with the simulated result from a few hundred meters up to 2.9 km. With the increased communication distance, reduced communication channel performance occurs from energy fluctuation and excess path loss caused by turbulence effect. Thus the turbulence strength tradeoff between separation distance and common volume size is investigated.
The author adopted both numerical method and MC simulation to demonstrate the performance of both visible and ultraviolet light communications with varies precoding, modulation scheme, channel conditions, and link geometries. These simulated and experimental results can provide insight into the link budget and system design for practical LOS VLC and NLOS UV communication systems.