【作者】 张海良；

【导师】 谭吉春； 常胜利；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2012， 博士

【摘要】 紫外光通信具有保密性高、全方位性好、抗干扰能力强等优点，是在要求“无线电静默”条件下进行通信的有效方法，在战术通信中具有重要的应用价值。建立三维的紫外光散射传输信道模型对于研究非视线紫外光通信的传输特性，以及紫外光通信系统的总体设计和分析、性能评估等有重要意义。本论文针对非视线斜程传输、绕障碍传输三维环境下紫外光传输特性问题等进行了研究。主要研究内容如下：一、建立了三维紫外光通信传输模型。已有的模型侧重紫外光通信系统接收端与发射端位于同一水平高度，在传输理论分析中不含有高度影响因素分析，且对障碍物通信环境考虑不足。本论文基于多次散射理论，运用蒙特卡洛方法，建立了三维紫外光传输信道模型，有效解决了如何分析复杂环境下紫外光传输特性的困难。二、根据建立的三维模型，重点分析了发射端与接收端之间斜程传输、无共同散射体以及绕障碍物传输特性，主要包括紫外光信号的脉冲展宽、能量密度、散射次数、传输损耗以及误码率等特性。紫外光通信系统从共同散射体情况变化到无共同散射体情况，接收光强减小3~5个数量级。脉冲响应宽度、接收光强、平均散射次数与距离成指数关系。斜程传输时应减小发射端和接收端之间的高度差，以利于减小平均散射次数，从而增加接收光强。紫外光绕障碍传输时，障碍物越高，最佳发射仰角和接收仰角增大；发射离障碍物越近，最佳接收距离越远，发射端距障碍物的距离从80m变到30m时，障碍物另一侧接收端的最佳接收距离从1m变到50m（障碍物高度80m）。并搭建了室外实验，验证了模拟结果。三、研究了全双工紫外光通信技术和多用户通信网络的连通性与互干扰。基于中心节点圆环面积泊松分布的节点模型，研究了紫外光网络互干扰与连通性。随着节点密度增加（从10/km~2增加到50/km~2），通信用户数增加，使得信噪比降低（从21.2dB降到2.4dB）；减小发射功率可以降低干扰(功率从10W减小到1W)，从而提高信噪比（从2.4dB提高到15.5dB）。但减小发射功率，增加了每个节点的路由跳数，这会带来网络延时和降低网络连通性。功率分别为10W和4W时，网络1-连通性分别为0.90和0.03。误码率越小（从10-3提高到10-6），连通性越差（1-连通性从0.99降低到0.78）。根据无共同散射体传输损耗结论，分析了空分复用技术实现全双工紫外光通信的可行性。传输距离越远，越小的接收仰角更适合全双工通信，当通信距离为200m，接收仰角小于61°时，可实现全双工通信；而当距离为500m时，接收仰角小于37°。本文的研究结论对紫外光通信系统的总体设计和分析、性能评估等有重要的指导意义。更多还原

【Abstract】 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.更多还原