【作者】 霍羽；

【导师】 徐钊；

【作者基本信息】 中国矿业大学 ， 通信与信息系统， 2013， 博士

【摘要】 抑制多径衰落、增加无线覆盖范围，仍然是当前煤矿井巷无线通信的关键问题。本文致力于研究井巷无线电波的发送和传播机理，以期通过天线的改进从源头上减少多径的影响。根据传播机理，研究巷道波导效应对天线辐射场分布的影响；建立便于定量分析电波传播参数的数学模型；分析井巷阵列天线信道传输特征并建立合理的信道模型。根据波导理论研究煤矿井巷电波传播机理：(1)推导井巷电波所有可能传输模式的空间方向及数量；(2)推导高模式电波传播损耗公式，考虑了由巷道壁粗糙度、倾斜度引起的散射损耗。在此基础上建立多波模模型，仿真分析井巷多波模传播特点。煤矿井巷中可激励出的传输波模数量有限，各波模空间相位是与巷道尺寸及载波频率有关的离散变量。为了解巷道中阵列天线波束控制所需关注的重要参数，为信道传输特征的分析提供理论依据，研究巷道中天线辐射场分布特性：(1)推导巷道中天线输入功率耦合至各传输波模的效率；(2)推导巷道中天线的方向函数，给出煤矿井巷天线的辐射场分布规律：巷道中天线的方向图乘积定理。仿真分析了巷道波导效应对天线辐射场分布的影响：天线安装位置是改变巷道中天线耦合效率和辐射场分布的重要参数。为便于计算无线信道中各路径波达方向、时延、传输功率等参数，根据巷道内有效射线必须与波导波模相匹配的推想，提出融合波导与射线理论的电波传播模型：(1)利用波导理论确定巷道内源射线的方向和数量；(2)根据几何光学基本定律，证明了巷道内射线传播路径的投影反射定律和投影夹角定律；(3)推导出射线到达接收面的位置、传播过程中经历的反射次数、入射到巷道壁的掠射角、路径长度与射线离开角的关系，对主动射线法进行改进，避免了传统主动射线法对三维射线复杂繁琐的迭代跟踪计算，降低了计算量；(4)利用接收球判断射线是否被接收。通过与实际测量数据相比较，验证了融合模型的合理性。煤矿井巷阵列天线空时信道建模与分析：(1)研究井巷阵列天线信道传输特征：在井巷中，利用阵列天线改变方向图的本质是利用天线控制巷道内各波模的激励，决定辐射场集中于哪些方向的关键不是阵元间距，而是各阵元在巷道中的位置；(2)根据信道传输特征，运用融合模型建立通用的阵列天线空时信道模型，既注重天线间各个子信道的衰落和空间相关性，也注重信号空间信息及各阵元相位导数的作用；(3)根据信道模型给出井巷内的功率时延谱和功率角度谱公式。通过仿真信道在时域、空域的脉冲响应，并与实测数据相比较，验证了该模型预测信号空时特性的可行性。更多还原

【Abstract】 In tunnels of coal mine underground, the key issue remains how to suppress thesevere multipath fading and to increase the wireless coverage. This paper is dedicatedto the research of the radio waves transmission and propagation mechanism, and try toreduce the multipath effects from the source by improving the antenna. In this work,the effect of the waveguide made by mine tunnels themselves on the radiation fielddistribution of the antenna is researched. A mathematical model is proposed, whichfacilitate to calculate the propagation parameters of the radio waves. Based on theabove study, the transmission characteristics of the channel for the antenna array areanalyzed. And then, a reasonable antenna array channel model is given.Firstly, this paper study the radio waves propagation mechanism based on themodal theory of the waveguide in coal mine tunnels.(1) Educe the spatial directionand the number of all allowed transmission modes in a tunnel.(2) Derive thepropagation loss of higher mode, including the refraction loss caused by the tunnelwalls and the scattering loss caused by the wall roughness and the wall tilt. On thisbasis, the multimode propagation in tunnels is modeled and analyzed by simulations.It is shown that the number of the allowed modes in a tunnel is limited; the spatialphase of each transmission mode is a discrete variable as a function of the tunnel sizeand the carrier frequency.Secondly, research the radiation characteristics of an antenna in coal minetunnels. It is very helpful to understand which parameters should be paid moreattention when apply and research the antenna array to form reasonable beams in atunnel, and then helpful to know about the transmission characteristics of the wirelesschannel of an antenna array.(1) Derive the power efficiency when the total power ofan antenna is coupled into the waveguide modes.(2) Educe directional functions ofthe antenna in coal mines. Then the radiation field distribution laws are provided,which are pattern product theorems of the antenna in coal mines. According to theabove derivations, the effects of the tunnel environments on the radiation fielddistribution of the antenna is simulated and analyzed. The results show that theinstallation location of the antenna is a significant parameter that could change thecoupling efficiency and the radiation pattern of the antenna.Thirdly, propose a fusion model that combined the modal theory and ray theoryin coal mine tunnels to facilitate the calculation of the channel parameters, such as AOD (Angle Of Departure), delay, transmission power of each path.(1) Based on thepresumption that the effective rays should match with the waveguide modes,determine the number of the launched rays and their AOD by the modal theory.(2)According to the theory of geometrical optics, prove the reflection law and theincluded angle law of the projection of the propagation path of a ray in a rectangulartunnel.(3) Deduce the arriving position, the reflections number and the travelingdistance of a ray as functions of its AOD.(4) Whether a ray hits the receiver or not isdecided by the reception spheres. Finally, the theoretical model is validated by theexperimental measurements.Lastly, develop the channel modeling and analysis for antenna array in coal minetunnels.(1) Research the channel transmission characteristics of antenna array. Intunnels underground, the essence of changing beams by antenna array is controlingthe excitation of each waveguide mode. Consequently, to go by appearances, the arrayelement spacing changes the directions which the radiation field focused on, but it isthe insertion position of each array element affects the radiation direction in actual.(2)According to the channel transmission characteristics, use fusion model to finish thespace-time channel model of the antenna array. The model not only focuses on thefading and the spatial correlation of each subchannel, but also focuses on the signalspatial information and the phase steering vector of each array element.(3) Providepower angular spectrum and power delay spectrum through the channel model.Simulations of the channel impulse response in the space and time domain arecompared with the experimental measurements. The results show that the theoreticalmodel is valid to predict the signal space-time characteristics.更多还原