Modeling and characterization of ultraviolet scattering communication channels

Abstract

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 vii 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.

Maximal Selective Transmit Diversity for Petahertz Wireless Communications With Continuous Waveform Detector

“…where A r denotes the effective area of the receiver and q s is the scattering phase function and is modeled as a combination of Rayleigh and Mie scattering phase function [26]. α s is the total scattering coefficient and is defined as the sum of the Rayleigh and Mie scattering coefficients.…”

“…where f χ (χ) represents the distribution of the instantaneously received SNR χ. Applying the Jacobean transformation, f χ (χ) is derived as illustrated in (26). Substituting ( 26) into ( 25) and utilizing the identity [33, eq.…”

Optimum Cooperative Spectrum Sensing Technique for Multiuser Ultraviolet Wireless Communications

“…C 2 n denotes the refractive index coefficient of atmospheric turbulence channel. h s in (1) denotes the attenuation term due to atmospheric scattering and can be modeled as [10] h s = A r α s q s φ 2 t φ r sin (ψ t + ψ r ) 12 sin 2 ψ r + φ 2 r sin 2 ψ t 96d sin ψ t sin 2 ψ r 1 − cos φ t 2 exp α t d(sin ψ t +sin ψ r ) sin(ψ t +ψ r )…”

“…where J is the Jacobean matrix. After substituting the values in ( 7), the closed-form expression of f χ (χ) is derived as (10).…”

A Novel Blind Spectrum Sensing Technique for Multi-User Ultraviolet Communications in Atmospheric Turbulence Channel

“…H 0 and H 1 represent the two hypotheses of the UV signal absence and presence, respectively. P r is the received optical power equal to P t × P L , where P t is the transmitting power and P L is the UV channel path loss given by [12]…”