高铁无线通信系统中的隧道信道模型

发布时间：2018-05-22 18:38

  本文选题：高铁无线通信网络 + 高铁隧道信道模型　； 参考：《山东大学》2017年博士论文

【摘要】：作为第五代(5thGeneration,5G)移动通信系统的典型应用场景,高速移动场景(譬如:高铁无线通信场景)正备受关注。伴随高铁的迅猛发展,高铁通信系统也快速发展起来。高铁中乘客密集且用户的通信需求不断增加,因而会产生大量的无线通信数据,而这些数据传输已经远远超过目前高铁通信系统的承受能力,因此,亟需提出一种可以提供较高网络容量和可靠通信服务的新一代高铁通信系统。高铁在实际运行过程中会遇到诸多不同场景,如开阔场景、高架桥、路堑场景、车站及隧道场景等。对于高铁隧道场景而言,由于其自身的结构特点,使得无线信号在高铁隧道内的传输不同于在其他几种场景中的传输。为了设计和评估未来高铁隧道无线通信系统,一个能够准确描述高铁隧道大尺度和小尺度特性的信道模型是不可或缺的。现有的隧道模型研究主要侧重于大尺度衰落特性分析,而忽略了小尺度衰落特性。因此,考虑到目前仍然缺少准确、全面的高铁隧道信道模型和相应的统计特性分析,本博士课题将致力于研究非平稳的多输入多输出(Multiple-Input Multiple-Output,MIMO)高铁隧道信道模型。本论文中,我们首次全面地综述了高铁隧道场景信道建模,归纳了一些目前已开展的隧道信道测量工作,总结了基于不同建模方法的信道模型,并列出了现有的隧道信道特性。结合高铁隧道场景的有限可视性、空间狭长性特点以及产生的波导效应等,我们将着重从以下几方面开展高铁隧道信道建模工作。首先,考虑俯仰角的影响,更加形象、准确地描述高铁三维(3Dimentional,3D)隧道信道模型,弥补现有的二维(2 Dimentional,2D)信道模型之不足。其次,引入高铁隧道信道的非平稳特性。接收端的快速移动会带来较大的多普勒频移,这使得传统的信道广义平稳的假设不再成立。然后,考虑到隧道内存在大量的反射、散射等传播机制,我们首次采用单次反射(Single-bounced,SB)和多次反射(Multiple-bounced,MB)相结合的方式来建模隧道内信号的传输。最后,侧重研究小尺度信道特性。现有的隧道信道建模主要针对大尺度衰落研究,简化了小尺度衰落特性分析。但小尺度衰落特性对于无线系统的设计也是至关重要的,因而不容忽视。基于上述几点,我们需要提出一种新型的高铁隧道信道模型来准确地描述高铁隧道信道特性。从确定性建模的角度,我们首次提出采用模式方法建模高铁隧道信道,分析了一些小尺度信道特性的影响及功率分布情况等。基于现有的多模分布模型,我们扩展提出了时间相关的多模信道模型。基于所提模型,研究了信道内一系列相关的统计特性,如:时间自相关(Autocorrelation Function,ACF)、功率谱密度(Power Spectrum Density,PSD)及功率分布情况等。同时,还研究了不同工作频率、隧道尺寸、模式情况对ACF的影响等。此外,基于高铁隧道射线追踪模型,我们分析了不同参数,例如载波频率、隧道尺寸、隧道形状和天线极化等对隧道内信号传输功率的影响。从随机建模的角度,考虑到隧道的尺寸、形状等均会对隧道内信号的传输产生一定影响,提出了基于几何特性的随机信道模型。对于长方形或马蹄形隧道,将传播空间抽象为一个长方体。假设在封闭的长方体隧道空间中,存在着大量的散射体随机分布在隧道内壁上。结合WINNER模型的建模方法和隧道本身的结构特点,将隧道内的散射体分布转化为一系列的簇随机分布在隧道内部。基于该建模思路,考虑隧道内SB和MB的情况,提出了 3D非平稳宽带几何随机理论信道模型。然后,分别对水平和俯仰角采用修正的等面积法(Modified Method of Equal Area,MMEA)得到离散角度值,提出相应的仿真模型。最后,基于所提模型,研究了隧道信道模型的一系列统计特性,分析了信道的非平稳特性,并通过测量数据对所提模型进行验证。现有的高铁隧道中,圆形或拱形隧道也占据了一定比例。考虑将拱形或圆形隧道近似抽象为圆柱体来进行建模,简化计算,开展基于簇分布的信道建模。首先,随机产生一组初始的簇角度均值,通过角度均值和圆柱体联合确定簇的位置。一旦角度确定,簇的位置坐标即可得到。此时,发送端、接收端和簇的位置坐标都可确定,所有的信道信息均可得到,如到达角、离开角、时延和传播距离等,从而得到3D的非平稳宽带圆形隧道信道模型。此外,考虑到水平和俯仰角的相互关系,采用等体积法(Method of Equal Volume,MEV)对水平和俯仰角进行联合估计,提出了相应的仿真信道模型。基于所提信道模型,研究了信道的一些小尺度衰落特性,最后,将所提信道模型特性与测量数据进行验证。综上所述,我们考虑到隧道内俯仰角的影响,采用3D隧道信道建模,并且通过SB和MB的情况体现隧道内的多次反射、散射等,采用角度时变特性来建模高铁隧道信道的非平稳特性,提出理论和仿真信道模型,并通过测量数据进行验证。本文所提的隧道信道模型,对于5G移动通信系统中高铁隧道系统的设计、测试和性能评估分析等,都具有重要意义。
[Abstract]:As the typical application scene of the fifth generation (5thGeneration, 5G) mobile communication system, high speed mobile scene (such as high speed wireless communication scene) is being paid much attention. With the rapid development of high speed rail, the high-speed rail communication system is also developing rapidly. The data transmission has far exceeded the capacity of the current high-speed communication systems. Therefore, it is urgent to propose a new generation of high-speed communication systems that provide high network capacity and reliable communication services. High speed rail will encounter many different scenes in the actual operation, such as open scene, viaduct, cutting scene, station For the high speed tunnel scene, because of its own structural characteristics, the transmission of wireless signals in the high speed railway tunnel is different from that in several other scenes. In order to design and evaluate the wireless communication system of the future high speed tunnel, a channel that can accurately describe the large and small scale characteristics of the high speed tunnel. The model is indispensable. The existing study of tunnel model mainly focuses on the analysis of large scale fading characteristics and neglects the small scale fading characteristics. Therefore, considering the lack of accurate, comprehensive high speed tunnel channel model and the corresponding statistical characteristics analysis, the PhD topic will be devoted to the study of non-stationary multiple input and multiple output (M Ultiple-Input Multiple-Output, MIMO) high speed tunnel channel model. In this paper, we first comprehensively summarized the scene channel modeling of high speed railway tunnel, summed up some existing tunnel channel measurement, summed up the channel model based on different modeling methods, listed the existing tunnel channel characteristics, combined with the high speed tunnel. The finite visibility of the scene, the spatial slit and the waveguide effect and so on, we will focus on the modeling of the tunnel in the following several aspects. Firstly, considering the influence of the pitch angle, the 3Dimentional (3D) channel model of the high speed railway is described more accurately, and the existing two dimensional (2 Dimentional, 2D) letter is made up. Secondly, the non-stationary characteristics of the high speed tunnel channel are introduced. The fast movement of the receiver will bring a larger Doppler shift, which makes the traditional hypothesis of the broad sense of the channel no longer established. Then, we take a single reflection (Single-bounced) for the first time considering the existence of a large number of reflection and scattering mechanisms in the tunnel. SB) and multiple reflection (Multiple-bounced, MB) are combined to model the transmission of the signal in the tunnel. Finally, the characteristics of the small scale channel are focused on. The existing tunnel channel modeling is mainly aimed at the large scale fading research, which simplifies the analysis of the small scale fading characteristics. However, the small scale fading characteristic is also critical to the design of the wireless system. As a result, we need to put forward a new high speed tunnel channel model to accurately describe the channel characteristics of the high speed tunnel. From the deterministic modeling point of view, we first propose a model method to model the high speed tunnel channel, and analyze the influence of a few small scale channel characteristics and the power distribution situation. Based on the existing multimode distribution model, we extend the time dependent multimode channel model. Based on the proposed model, we study a series of related statistical properties in the channel, such as Autocorrelation Function (ACF), power spectral density (Power Spectrum Density, PSD) and power distribution. In addition, based on the ray tracing model of high speed railway tunnel, we analyze the influence of different parameters, such as the carrier frequency, tunnel size, tunnel shape and antenna polarization on the transmission power in the tunnel. From the angle of random modeling, we consider the size and shape of the tunnel, and so on. A random channel model based on geometric characteristics is proposed for the transmission of signals in the tunnel. For rectangular or horseshoe tunnel, the propagation space is abstracted as a rectangular body. It is assumed that there are a large number of scatterers distributed along the inner wall of the tunnel in the closed rectangular tunnel space. The WINNER model is combined with the model. The scattering body distribution in the tunnel is transformed into a series of random distribution in the tunnel. Based on the modeling idea, the SB and MB in the tunnel are considered, and the 3D non-stationary broadband geometric random theory channel model is proposed. Then, the modified equal area method is adopted for the level and pitch angle. Modified Method of Equal Area, MMEA) obtained the discrete angle value and put forward the corresponding simulation model. Finally, based on the proposed model, a series of statistical characteristics of the tunnel channel model are studied, the non-stationary characteristics of the channel are analyzed, and the model is verified by the measured data. In the existing high speed tunnel, the circular or arched tunnel is also occupied. According to a certain proportion, the arch or circular tunnel is considered as a cylinder to be modeled, and the channel modeling based on the cluster distribution is simplified. First, a set of initial cluster angle mean is randomly generated, and the position of the cluster is determined by the angle mean and the cylinder. The position coordinates of the cluster can be obtained by the denier angle. The location coordinates of the transmitter, the receiver and the cluster can be determined, and all the channel information can be obtained, such as the angle of arrival, the departure angle, the time delay and the propagation distance, and so on, the 3D non-stationary broadband circular tunnel channel model is obtained. In addition, the equal volume method (Method of Equal Volume, MEV) is used to take into account the relationship between the level and the pitching angle. Based on the proposed channel model, some small scale fading characteristics of the channel are studied based on the proposed channel model. Finally, the characteristics of the proposed channel model and the measured data are verified. In summary, we take into account the influence of the tunnel elevation angle in the tunnel, and use the 3D tunnel channel modeling, and pass through the channel model. The situation of SB and MB reflects the multiple reflection and scattering in the tunnel, and uses the angle time-varying characteristic to model the non-stationary characteristics of the high speed tunnel channel. The theoretical and simulation channel models are proposed and verified by the measurement data. The tunnel channel model proposed in this paper is designed, tested and sexed for the high speed railway tunnel system in the 5G mobile communication system. It is of great significance to be able to evaluate and analyze.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U285.2;TN92
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本文编号：1923191