高速移动环境中基于理论方法的无线信道建模研究

发布时间：2018-04-21 23:36

本文选题：高铁无线信道 + 随机传播图　；参考：《北京交通大学》2014年硕士论文

【摘要】：近年来,我国告诉铁路(“高铁”)的迅速发展受到了国际广泛关注,同时也极大的促进了国内经济增长。随之而来的高铁通信成为了当前学术界和产业界的热点问题。现有铁路通信系统已无法满足未来的高铁通信需求,新一代铁路通信系统的研究与开发势在必行。众所周知,信道模型对于无线通信系统的设计起着至关重要的作用。大尺度衰落模型可用于网络的覆盖预测和干扰分析,而小尺度衰落模型则为系统仿真和算法评估提供参考。本文首先介绍高铁无线信道电波传播特性,根据近年来几次高铁信道测量获得的大尺度传播模型,总结归纳了不同场景不同带宽下的测量结果,罗列出高铁不同场景下大尺度衰落特征。同时介绍小尺度衰落特征,分析高铁无线信道关键参数(如K因子、多普勒(Doppler)功率谱、多径功率延迟潜)提取方法。接着,介绍了其中一种情况下信道容量的计算方法,结合高铁实际测量数据,统计分析高铁不同场景下遍历容量和中断容量的变化特征。接下来本文采用频域/时域理论分析的模型构建方法,建立无线移动通信系统在高速移动场景下的信道模型。(1)基于频域的随机传播图的信道建模方法,通过将传播环境中的反射物和传播射线抽象为有向图中的定点和边,可研究出多个反射体、散射体反射或散射带来的多次反射特性,最终获得整个传播信道的传递函数。同时根据高铁实际测量数据、利用Von Mises分布模拟接收端到达角等方法,校准和验证随机传播图建模方法的可行性和研究价值。基于随机传播图方法对高铁典型移动场景进行信道建模,根据仿真得到信道的冲激响应(Channel Impulse Response-CIRs)，，分析信道关键参数信息,讨论高铁移动信道衰落特性。(2)基于时域的几何随机散射理论建模,信道特征是基于反射物的散射线在接收端射线迭加获取。通常,为了时域迭加的方便和简化数学推导,这种建模方法在传播模型抽象图中假设无线电波在反射物和散射物反射次数有限。本文主要重点研究单环和椭圆模型,深入研究其无线信道时间域和空间域的相关函数,分别推导空-时相关函数的闭合表达式。目前,高铁场景下的信道建模主要是基于实际的信道测量数据。然而,高铁信道测量工作开展难度较大,很难获取足够的测量数据用于信道建模。随着信道建模理论的发展,随机传播图和几何散射理论是两种可靠、准确的信道建模方法。为此,本文基于这两种先进的建模理论构建高铁场景下的信道模型,该模型不仅与实际的测量结果相匹配,而且能够用于评估高铁多天线系统性能。
[Abstract]:In recent years, the rapid development of China's tell railway ("high-speed railway") has received extensive international attention, but also greatly promoted the domestic economic growth. The following high-speed communication has become a hot issue in academia and industry. The existing railway communication system can not meet the needs of future high-speed railway communication, so the research and development of the new generation railway communication system is imperative. As we all know, channel model plays an important role in the design of wireless communication system. The large scale fading model can be used for the coverage prediction and interference analysis of the network, while the small scale fading model can be used as a reference for system simulation and algorithm evaluation. This paper first introduces the characteristics of radio wave propagation in high speed rail wireless channel. According to the large scale propagation model obtained from several high speed railway channel measurements in recent years, the measurement results under different scenarios and different bandwidth are summarized. The characteristics of large scale fading in different scenarios of high-speed train are listed. At the same time, the characteristics of small scale fading are introduced, and the extraction method of key parameters (such as K factor, Doppler Doppler spectrum, multipath power delay submergence) for high speed wireless channel is analyzed. Then, the calculation method of channel capacity in one of the cases is introduced, and the variation characteristics of traversal capacity and interrupt capacity under different scenarios of high-speed rail are analyzed by combining with the actual measurement data of high-speed rail. Then, this paper uses the model construction method of frequency domain / time domain theory analysis to establish the channel model of wireless mobile communication system under high speed mobile scene. (1) the channel modeling method based on random propagation graph in frequency domain. By abstracting the reflectors and propagating rays in the propagation environment into fixed points and edges in the directed graph, the properties of multiple reflectors, scatterers or scattering can be studied. Finally, the transfer function of the whole propagation channel can be obtained. At the same time, the feasibility and research value of the stochastic propagation graph modeling method are calibrated and verified by using the Von Mises distribution to simulate the arrival angle of the receiver according to the actual measurement data of high-speed rail. Based on the stochastic propagation graph method, the channel model of the typical high-speed railway mobile scene is built, and the channel impulse response channel Impulse response to CIRs is obtained by simulation, and the critical channel parameter information is analyzed. In this paper, the fading characteristics of high speed mobile channels are discussed. The model is based on the geometric random scattering theory in time domain. The channel features are obtained by superposition of reflecting-based scattered rays at the receiving end. In order to simplify the mathematical derivation of superposition in time domain, this modeling method assumes in the abstract map of propagation model that the number of reflections of radio waves in reflectors and scatters is limited. In this paper, the single ring and elliptic models are studied, and the correlation functions in time domain and space domain of wireless channel are studied in depth, and the closed expressions of space-time correlation function are derived respectively. At present, the channel modeling in the high-speed train scene is mainly based on the actual channel measurement data. However, it is difficult to obtain enough measurement data for channel modeling. With the development of channel modeling theory, stochastic propagation graph and geometric scattering theory are two reliable and accurate channel modeling methods. Therefore, based on these two advanced modeling theories, this paper constructs the channel model in the high speed train scenario. The model not only matches the actual measurement results, but also can be used to evaluate the performance of the high-speed rail multi-antenna system.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

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