Research On Wireless Ultraviolet Scattering Charcteristics Of The Rain And Fog Channel

Ultraviolet(UV)communication is a new type of communication mode,which uses the UV light of 200nm?280nm solar band as the carrier.It can realize the Non-Line-of-Sight(NLOS)communication in complex environment by the scattering of atmospheric molecules and aerosol particles.Under different weather conditions,the path loss and Bit Error Rate(BER)of UV communication system change with the particles density,particles size and geometric parameters of transmitter and receiver.The scattering of rain and fog particles will also bring serious inter symbol interference to the UV communication system,which will effect the channel performance of the UV communication system.By studying the channel characteristics of UV light in rain and fog environment,which can provide theoretical basis for improving wireless UV scattering communication performance.In this thesis,the UV single scattering and multiple scattering communication link transmission model are used to study the channel characteristics such as UV scattering intensity distribution and path loss under different rainfall intensities and different fog density.The specific research contents of this works are as follows:(1)The channel model of UV light transmission in rain and fog environment are improved.Using T-matrix theory and Monte Carlo photon trajectory pointing probability method,the effect of different rainfall intensity,particles shape and particles size on path loss and scattering intensity distribution are simulated.The simulation results show that the communication quality in rainfall environment is worse than that in sunny days,the path loss increases,and the path loss in Line-of-Sight(LOS)communication is reduced by about 7 dB compared with that in NLOS communication.With the increase of rainfall intensity,particles size and particles orientation angle,the scattering intensity curve shows a downward trend,and the rainfall intensity has the greatest influence on the scattering intensity distribution.(2)The particles size distribution of land fog and sea fog are fitted by generalized Gamma distribution.The influence of different fog density on path loss in two kinds of fog media are studied by Mie scattering theory,and the BER and pulse response of sea fog and land fog multiple scattering are analyzed.The experimental and simulation results in fog environment are compared and analyzed.For the land fog,when the distance of UV NLOS communication is less than 100m,the increase of fog density can reduce the path loss and BER of the system.At the same fog density,the path loss and BER of sea fog increase with the increase of fog density.In summary,this thesis mainly studies wireless UV scattering characteristics of rain and fog channel,and the modeling method of UV scattering channel in rain and fog environment are given.Monte Carlo photon trajectory pointing probability method is used to simulate and analyze the multiple scattering channel characteristics of rain and fog channel.