紫外光通信系统传输模型研究

发布时间：2018-01-08 09:41

本文关键词：紫外光通信系统传输模型研究　出处：《北京邮电大学》2014年博士论文　论文类型：学位论文

【摘要】：曰盲紫外光通信是近年来兴起的一种无线光通信技术,具有非视距、链路稳定可靠、抗干扰能力强、安全隐蔽、可全天候工作等一系列独特的潜在优势。大气粒子的散射作用与光湍流效应使得紫外光通信信道具有随机性,给信号传输带来不确定因素。因此,研究紫外光通信的大气信道特性有着重要意义。本论文围绕大气散射信道这一关键问题展开创新性理论研究,深入探讨了非视距紫外光通信的大气信道特性,主要成果如下： 1.采用微元光束法,首次建立了任意收发机指向几何条件下的单散射传输模型,可准确计算接收能量值。对从发射机立体角内以任意角度发射出的光束与接收机视场体的相交情况进行了详细分析,消除了以往单散射模型中发射机光束体与接收机视场体的轴线必须共面的限制。 2.建立了非共面条件下的单散射简化模型,仿真结果显示：在发射光束或接收视场较窄的前提下,可对任意收发机指向的紫外光通信链路性能进行快速的近似估计,与以往的简化模型相比具有更高的准确性,适用范围也更广,特别适用于紫外Ad Hoc网络等需要快速计算散射功率的场景。 3.基于已建立的微元光束单散射模型,推导了非视距紫外光通信的时延扩展与脉冲响应函数,并进行了蒙特卡罗仿真验证。建立了收发机非共面条件下的蒙特卡罗多散射模型,首次仿真分析了在任意收发机几何参数及不同通信距离的条件下,单散射与多散射对应的接收能量和脉冲展宽之间的误差大小,给出了非视距紫外光通信中满足单散射近似的收发机几何条件。 4.考虑大气湍流导致闪烁衰减的情况下,推导了随机混浊介质中的非视距紫外光通信湍流模型。利用湍流涡旋的散射效应首次建立了随机湍流介质中的紫外光通信单散射功率模型,分析了适用于紫外光通信的能量谱密度,以及单散射辐照度与湍流特征参数、光波波长、收发机距离等的关系,探讨了该介质中的散射作用与瑞利散射、米散射之间的关联性。 5.推导了空间相关湍流衰落中的多接收机的非视距联合空间分布,分析了基于最大似然策略以及选择合并、最大比合并、等增益合并等线性合并技术实现的紫外光通信空间分集接收系统的性能。仿真结果表明：当大气湍流较弱时,最大似然策略得到的性能比最大比合并和等增益合并更好,但优势并不十分明显；随着湍流变得更强,在高信噪比场景中,最大比合并和等增益合并方法要优于最大似然分集接收。
[Abstract]:Blind UV communication is a kind of wireless optical communication technology which has emerged in recent years . It has a series of unique potential advantages such as non - apparent distance , reliable link stability , strong anti - jamming capability , safe concealment , all - weather work and so on . The scattering effect of atmospheric particles and the effect of light turbulence make the channel of ultraviolet light have randomness and cause uncertainty . Therefore , it is important to study the atmospheric channel characteristics of ultraviolet communication . In this paper , an innovative theoretical study is carried out about the key problem of atmospheric scattering channel , and the atmospheric channel characteristics of non - sight distance ultraviolet communication are discussed in detail . 1 . A single - scattering transmission model with arbitrary transceiver pointing to geometric conditions is established for the first time by adopting a micro - beam method , and the received energy value can be accurately calculated . The intersection between the light beam emitted from any angle in the solid angle of the transmitter and the field of view of the receiver is analyzed in detail , and the limitation that the axis of the transmitter beam body and the receiver field of view of the receiver must be coplanar is eliminated in the conventional single - scattering model . 2 . The simplified model of single scattering under non - coplanar condition is established , and the simulation results show that , under the premise of narrow transmitting beam or receiving field of view , the fast approximate estimation can be carried out on the performance of the UV communication link which can be directed by any transceiver , which has higher accuracy and wide application range compared with the previous simplified model , and is especially suitable for the scene with the need of fast calculation of scattered power in the ultraviolet Ad Hoc network and the like . 3 . Based on the established micro - beam single - scattering model , the delay spread and impulse response function of non - sight distance ultraviolet communication is deduced , and Monte Carlo simulation verification is carried out . A Monte Carlo multi - scattering model under non - coplanar condition of the transceiver is established . The error size between the received energy corresponding to the single scattering and the multi - scattering and the pulse broadening are analyzed for the first time , and the geometrical conditions of the transceiver that satisfy the single scattering approximation in the non - sight distance ultraviolet communication are given . 4 . In the light of the scintillation decay caused by atmospheric turbulence , the non - sight distance ultraviolet communication turbulence model in the random turbid medium is derived . The scattering effect of the turbulent vortex is used for the first time to establish the UV communication single scattering power model in the random turbulence medium . The relation between the energy spectral density suitable for the ultraviolet communication and the characteristic parameters of the turbulence , the wavelength of the light wave and the distance of the transceiver are analyzed . The correlation between the scattering effect and the Rayleigh scattering and the meter scattering in the medium is discussed . 5 . The spatial distribution of multi - receiver in spatial - dependent turbulent fading is derived . The performance of the spatial diversity receiving system based on the maximum likelihood strategy and the combination of choice of combining , maximum ratio combining , and so on is analyzed . The simulation results show that when the atmospheric turbulence is weak , the maximum likelihood strategy has better performance than the maximum ratio combining and the equal gain combining , but the advantage is not quite obvious . As the turbulence becomes stronger , the maximum ratio combining and the equal gain combining method is better than the maximum likelihood diversity reception in the high signal - to - noise ratio scene .

【学位授予单位】：北京邮电大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.1

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