高移动性无线通信系统空间信道测量技术研究

发布时间：2018-02-09 20:56

本文关键词： 信道测量空间信道建模双站合成孔径雷达高铁无线通信信道多输入多输出　出处：《电子科技大学》2017年博士论文　论文类型：学位论文

【摘要】：20世纪90年代后期,多输入多输出(Multiple-Input Multiple-Output,MIMO)技术的兴起为无线数字通信系统带来了一场技术革新。与正交频分复用技术相结合,MIMO已成为从IEEE802.11无线局域网到4G LTE(Long Term Evolution)系列通信技术的物理层标准,也是5G移动通信以及高速列车无线通信建议规范LTE-R(LTE for Railway)的关键核心技术。为了更好的评估、设计和优化MIMO系统,最有效和最直接的方法就是理解MIMO信道传播机制的空间多样性、定位信道传播环境中的散射体,从而探测每个信道冲激响应分量的出发和达到方向,分析接收天线之间的衰落相关性和预测通信链路的可靠性和容量。目前,获取MIMO信道空域特征的信道测量技术通常有两类方法:机械转动定向天线法和多天线系统测试法。其中,机械转动定向天线的方法,除了耗时以外,只适用于静态信道或者较低多普勒频率信道的测量。随着天线阵列的增大,多天线系统测试法需要对收集到的测试数据进行大量后处理,即使采用高性能的阵列方向估计算法,如MUSIC、SAGE、和ESPRIT,运算复杂度也很高,系统成本大。然而对于一些特殊的场景,如高速铁路列车(High-Speed Railway,HSR)无线信道环境,除了高速移动性以外,极高的安全性要求也让信道测量工作者难以在现有的HSR运行平台上布局复杂的信道探测设备,使得传统的信道测量方法难以实施。基于特定通信场景的空间信道模型是发展基于MIMO无线新技术标准的重要基础,也是评定特定环境下MIMO技术性能的根本出发点。本文以高速铁路列车无线通信系统为背景,探讨高速运动场景下进行MIMO信道测量的有效新方法。本文的主要工作如下:1.提出一种基于双站合成孔径雷达(Bistatic Synthetic Aperture Radar,BiSAR)技术的新颖信道测量方法。本文将信道测量问题投影到BiSAR场景重构技术中,建立了一个固定发射机和匀速运动车载接收机信道传播环境下的ST-BiSAR(Stationary Transmitter BiSAR)几何模型。该模型很好地匹配了铁路HSR无线通信的特定场景,通过BiSAR的场景重构技术定位信道中的散射体,从而提取信道特征,简化信道测量。2.设计基于ST-BiSAR技术的信道仿真器。信道仿真器将具体的无线通信信道场景映射到ST-BiSAR的几何模型中,分析成像空间的三维分辨率,设计合理的三维成像算法,重构出三维信道场景;基于信道散射体的三维分布地图,提取出信道特征参数。根据成像的散射体图像性能,对比信道特征参数的仿真结果和理论数值,评估出系统性能。本文利用信道仿真器对HSR信道的仿真分析结果,验证了基于ST-BiSAR技术的信道测量方法是可行的。3.实现ST-BiSAR通信环境的三维场景重构。本文采用经典时域back-projection(BP)算法生成多层二维场景平面图像,利用多普勒聚焦原理提取散射体的高度信息,构建出信道散射体的三维地图。通过分析散射体的聚焦成像性能、散射体的成像地图和信道的特征参数值,验证了本文采用的三维信道成像技术是有效的。4.分析影响散射体成像或信道特征参数提取的因素。本文从散射体的位置分布、合成孔径的时间、探测信道的带宽和成像图像的分辨率等方面,详细讨论了这些因素在不同参数设置下对散射体成像性能、信道特征参数提取的影响。从而为未来的研究工作提供参考。5.开展基于ST-BiSAR技术的信道测量现场试验。在充分利用现有设备的基础上,根据最大化性能、最小化成本的原则,本文设计了以通用软件无线电平台(Universal Software Radio Peripheral,USRP)为核心设备的信道探测发射端和接收端。通过平台传输测试、静止测距和位置定位能力对ST-BiSAR信道探测平台的性能进行了验证测试。开展了以固定的车载发射机和近乎匀速运行的车载接收机布局的ST-BiSAR无线通信场景的现场试验。通过试验的初步结果进一步验证了基于ST-BiSAR技术信道测量方法的工程实践性,并指出信道探测设备需要改进的地方。综上所述,本文提出的基于BiSAR技术的信道测量方法的优越性有三点:1).成本低、探测设备简单,单通道足够探测获取MIMO空域特征;2).信道空域分辨率更高,尤其是较长距离的无线传播信道;3).场景适应性强,特别是常规信道测量方法过于复杂、测量设备过于庞大和昂贵的信道场景,如高速铁路无线通信信道。针对HSR信道场景,本文通过信道仿真和现场测试的初步结果验证了基于BiSAR技术的信道测量方法满足理论可行性和工程实践性。
[Abstract]:In late 1990s, multiple input multiple output (Multiple-Input Multiple-Output MIMO) technology has brought a technological innovation to the wireless digital communication system. Combined with orthogonal frequency division multiplexing technology, MIMO has become the IEEE802.11 wireless LAN to 4G LTE (Long Term Evolution) physical layer standard series communication technology, mobile communication is 5G and the high-speed train wireless communication standard LTE-R (LTE for Railway proposal) key core technology. In order to better assess the design and optimization of MIMO system, the most effective and most direct method is to understand the MIMO channel propagation mechanism of space diversity, scattering body positioning channel propagation environment, so as to detect each channel impulse response component the departure and reach the receiving antenna direction, analysis between the fading correlation and prediction of communication link reliability and capacity. At present, access to MIMO channel space Channel measurement technology domain features there are two methods: mechanical rotation method of directional antenna and multi antenna system test method. The method of mechanical rotation directional antenna, in addition to time-consuming, measurement is only applicable to the static channel or low frequency Doppler channel. With the increase of the antenna array, multi antenna system test method to test the data collected are a lot of postprocessing, even with the array of high performance estimation algorithms, such as MUSIC, SAGE, and ESPRIT, the computational complexity is very high, the cost of the system. However, for some special scenes, such as high-speed trains (High-Speed Railway HSR) wireless channel environment, in addition to high mobility besides, high security requirements for workers to channel measurement in HSR platform on the existing layout of complex channel detection equipment, the traditional channel measurement method is difficult to implement. The spatial channel model based on scene specific communication is an important foundation for the development of new wireless technology based on MIMO standard, but also to assess the specific environment of basic performance of MIMO technology. Based on the background of wireless communication system for high-speed railway train, to explore a new effective method for MIMO channel measurement of high speed scenarios. The main work of this paper is as follows: 1. proposed a bistatic synthetic aperture radar (Bistatic Synthetic Aperture Radar, based on the novel BiSAR) channel measurement technology. This paper will channel measurement problem projected onto the BiSAR scene reconstruction technology, set up a fixed transmitter and receiver channel uniform motion vehicle communication environment ST-BiSAR (Stationary Transmitter BiSAR) of the geometric model. The model matches very well the specific scene of railway HSR wireless communication, by positioning the scene reconstruction technology of BiSAR channel in bulk Shoot the body, so as to extract the characteristics of the channel simplified.2. channel measurement design of channel simulator based on ST-BiSAR technology. The geometric model of channel simulator specific wireless communication channel is mapped to the ST-BiSAR scene in 3D imaging spatial resolution analysis, rational design of the three-dimensional image, reconstruct 3D scene 3D map of the distribution channel; channel scattering based on the extracted channel parameters. According to the image performance of scattering imaging, numerical simulation results of channel characters and theory, to evaluate the performance of the system. This paper uses the channel simulation of HSR channel is really like the results of the analysis, to verify the channel measurement method based on ST-BiSAR technology is the 3D reconstruction of ST-BiSAR communication environment the feasible.3.. This paper uses the classic back-projection domain (BP) algorithm to generate multi dimensional scene plane image, using Doppler poly The focal height information of scatterers extraction principle, construct the three-dimensional map of channel scatterers. By focusing on the analysis of imaging performance of scatterers, characteristic parameters of imaging map and channel scattering value, verified the technology of 3D imaging channel used in this paper is effective.4. analysis of factors affecting the scattering imaging or channel feature extraction this article from the position. The distribution of scatterers, synthetic aperture time, detecting channel bandwidth and image resolution and so on, these factors on the performance of imaging scatterers on different parameters was discussed in detail. The effect of extraction of channel characters. So as to provide reference to carry out.5. channel measurement experiment based on ST-BiSAR Technology for the research work in the future. Based on the full use of existing equipment, to maximize performance and minimize the cost principle, this paper designs the general software radio Electrical (Universal Software Radio Peripheral platform, USRP) is the core equipment of the detection channel transmitter and receiver. Through the platform transmission test, static ranging and positioning capability is tested and verified on the performance of ST-BiSAR channel detection platform. To carry out on-site ST-BiSAR wireless communication systems with fixed transmitter and receiver on-board vehicle near uniform layout run the test. The results further validate the engineering practice of ST-BiSAR technology based on channel measurement method, and pointed out the need to improve the local channel detection equipment. To sum up, the superiority of the channel measurement method based on BiSAR technology has three points: 1). The detection of simple equipment, low cost, single channel detection to obtain enough MIMO spatial feature; 2). Channel spatial resolution is higher, especially the long distance wireless communication channel; 3). The scene. Should be strong, especially the conventional channel measurement method is too complex, the channel scene is too large and expensive measurement equipment, such as high-speed railway wireless communication channel. According to the HSR channel scene, through the preliminary results of channel simulation and field test of the channel measurement method of BiSAR technology to meet the theoretical feasibility and engineering practice based on.

【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN92

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