Study On The Characteristics Of Propagation Of Ultraviolet Communication System

Ultraviolet(UV) communication has the advantanges like high secrecy, gooddirection and strong anti-jamming, it is the efficient method to communicate under thecondition of "wireless silence", and has important application value in tacticalcommunication. It can provide important guidance to set up the three-dimensionalscattering propagation model of UV for the propagation characrteristics ofnon-line-of-sight UV communication, the overall design, analysis and performanceevaluation of UV communication system. This paper studies the propagationcharacteristics of UV under three-dimensional environment like non-line-of-sight slantpropagation and round-obstacle propagation. The main contents of this paper are shownas follows:1. The three-dimensional propagation model of UV communication has been set up.The transmitter and the receiver of the UV communication system in the existing modelare in the same altitude, and complex communication environment is not been fullyconsidered. Three-dimensional propagation model of UV communication is set up inthis paper based on multiple-scatter theory and Monte-Carlo method, and this model isappropriate for the study of propagation characteristics under complex environment.2. Based on the three-dimensional model, the propagation characterisitics of slantpath, non-common volume and round-obstacle propagation are studied, which includedthe full-width half-maximum(FWHM) of the pulse, energy density, scattering count,propagation loss and bit error rate. If the UV communication system varies fromcommon scattering volume to non-common scattering volume, the detecting lightdensity dimishes about3~5degrees, FWHM, the detecting light density, the averagescattering count are proportional to the range. The difference of the vertical altitudes ofthe transmitter and the receiver shall be as small as possible if slant path is unavoidable.The best transmitting and receiving elevation angles are determined by the height of theobstacle and the FOVs of the system; the best range of the receiver to the obstacle variesfrom1m to50m as long as the range of the transmitter to the obstacle varies from80mto30m (the height of the obstacle is80m): smaller the range of the transmitter to theobstacle, bigger the range of the receiver to the obstacle. The simulation resultsmentioned above are validated by outdoor experiment.3. The full-duplex UV communication and the connectivity, mutual interference ofmultiple-user communication network are studied. The possibility of full-duplex UVcommunication based on space-resue is analyzed based on the conclusions ofnone-common scattering propagation. The small elevation angle of the receiver is morefit for full-duplex communication, full-duplex communication can be achieved when therange is200m and the elevation angle of the receiver is smaller than61°(when the range is500m, the elevation angle is37°). The mutual interference and connectivity of UVcommunication network are studied based on the Poisson distribution model of nodes.When density of the nodes increases (from10/km~2to50/km~2), the signal-to-noisedecreases (from21.2dB to2.4dB). When the power of source decreases (from10W to1W), the SIN increases (from2.4dB to15.5dB). But the network delay will increase andthe network connectivity will decrease. The1-connectivity of the UV communicationnetwork will decrease from0.90to0.03as long as the decreasing of the power from10W to4W. The bit error rate varies from10-3to10-6, the1-connectivity decreases from0.99to0.78.The conclusions of this paper can provide good guidance of the overall design,analysis and performance evaluation of UV communication system.