Research On The Influence Of Atmosphere Scattering On The Performance Of Non-Line-of-Sight Ultraviolet Communication Systems

Ultraviolet communication is a technology which uses ultraviolet light as thecarrier of signal in the atmospheric channel to realize information transmission, withthe strong secrecy, not need ATP system, can be used for non-line-of-sightcommunications, and therefore have a broad application prospect. Atmosphericchannel is the important factor to effect the ultraviolet communication systemperformance for the UV signal transmitting in the atmosphere. However, the existresearch on the influence of atmosphere scattering on the performance ofnon-line-of-sight ultraviolet communication system are only based on singlescattering model to analyze the influence of geometries on the path losses withnoncoplanar, and the single scattering model must undergo the difficult numericalintegration and cannot obtain analytical solution. Therefore, the original model shouldbe simplified to make it easier to get the analytical solution quickly. Meanwhile,considering the noncoplanar geometries, the multi-scatter model which can be used onany geometry is built to study the influence of the off-axis angles on thecommunication systems.The compositions of ultraviolet communication system are described in thispaper. The characteristics of atmospheric channel are introduced, and the effects ofatmospheric composition on the signal transmission are analyzed. We focus on theRayleigh scattering of ultraviolet photons caused by molecular and the Mie scatteringcaused by aerosol particles. The key devices of the transceiver are compared and theoptimal devices are chosen.In this paper the light power density function of single scattering model isderived with the spheroid coordinate system, and the influences of the geometries ofthe transceiver on the power density and impulse responses are analyzed. Consideringthat the solution of the single scattering model is very complicated, required to gothrough numerical integral and cannot obtain the analytical solution, we get theanalytical expression of the path loss, that can be reflect the influence each parameter of communication systems on the path loss clearly and obvious, by using a volume ofcircular truncated cone to approximate the effective scattering volume and theprogram’s run time is cut greatly. The expression is employed to simulate therelationship between the transmission distance and the date rates under the differentBER requirements. the influences of the visibility on the path loss and the data ratesunder the different BER requirements are studied. The multi-scatter model based onMonte Carlo method that can be applied to any geometry is established, and themathematical description of this model is deduced. And we obtain the coordinates ofthe recursive formulas of the photon migration by the coordinate transformation andthe judgment conditions of the photons receiving and the flight time calculationmethod of the photons. Comparing the curves of the impulse response which aregotten from the multi-scatter model and the single scattering model, the multi-scattermodel is verified. The influences of the off-axis angles on the impulse response andthe path loss with noncoplanar geometrics are studied with the application of themulti-scatter model.The work provides theoretical basis for designing non-line-of-sight UVcommunication systems, has some guiding meaning and reference value.