三维空间域MIMO链路信道建模及其性能分析

发布时间：2018-03-15 05:16

本文选题：信道模型　切入点：多输入多输出　出处：《南京信息工程大学》2017年硕士论文　论文类型：学位论文

【摘要】：近些年,迅速增长的无线通信业务需求使得无线通信系统在不断地进行改进。而在无线通信系统设计中,无线信道建模占据重要位置,是建立高品质的无线通信系统必要前提。MIMO (Multiple Input Multiple Output)技术由于能够有效的解决无线频谱有限性问题及提高信道容量的优势已引起广泛关注,但是该系统的性能受无线衰落信道以及接收与发射端天线阵列牵制。另外,信号传播好坏与无线信道的特性相关,所以建立有效而准确的信道模型十分重要。本文主要基于几何空间域信道建模及MIMO系统性能分析,主要有以下几个部分:首先,介绍了信号在无线信道中传输时遇到的大尺度衰落和小尺度衰落,主要介绍了两种衰落的类别和特点,并举出相应信道模型进行说明;并且又详细的介绍了常用信道模型:高斯衰落模型、瑞利衰落模型、莱斯衰落模型。其次,提出一种更适合描述宏小区移动通信环境的信道模型,通常在宏小区环境中基站处天线要高于附近全部建筑物来降低多径效应的影响,但是实际情况并非如此,因此根据这种情况建立更准确有效的信道模型。在该模型中,散射体采用高斯分布,并且分析了到达角度(Angle of Arrival,AOA)、到达时间(Time of Arrival,TOA)以及多普勒频移概率密度分布情况。仿真分析结果与其他模型比较,表明了该模型更适合描述实际情况中宏小区移动通信环境。然后,对于上述信道模型进行再一次的改进,面对移动通信空间环境是非对称性的情况,提出一种更符合实际情况的非对称空间信道模型。此模型不仅可以准确地描述信号传播环境非对称时信道的重要空时参数,还应用于MIMO接收系统信道性能仿真中,通过分析线性天线阵列和圆形天线阵列下数值仿真结果,发现圆形天线阵列相对更有优势。接着,本文提出一种适用于室内微小区移动通信环境中的三维(Three Dimensional,3D)空间MIMO信道模型,从二维分析扩展至三维空间域分析,增加了波达信号在竖直平面上传播特性。在该模型中,移动台周围不存在散射体,且此处看作为中心原点,还在基站处放置指向性天线。推导出了该空间信道模型在两个不同平面上的重要空时信道参数,如AOA和TOA的概率密度函数。通过仿真结果的对比,该MIMO信道模型能够较好的适用于室内微小区的移动通信环境中,为三维空间域信道研究提供了灵活多变的模型。最后基于三维空间域,提出了一种双筒型的理论信道新模型。由于散射体非均匀分布会使理论分析变得复杂且不易得到闭合解析式,因此假设散射体均匀分布于三维空间域中。该模型能够准确地描述室外宏小区环境下空间信道的重要空时参数,推导出了 AOA、TOA的概率分布函数,以及推导出三维空间域下多普勒频移(Doppler Shift,DS)概率分布函数。仿真结果表明,该三维空间域信道模型比二维信道模型更好更准确的描述了室外宏小区移动通信环境。
[Abstract]:In recent years, the rapidly growing demand for wireless communication services has led to the continuous improvement of wireless communication systems, and wireless channel modeling plays an important role in the design of wireless communication systems. The technology of multiple Input Multiple output, which is a necessary prerequisite for the establishment of high quality wireless communication systems, has attracted wide attention due to its advantages of effectively solving the problem of limited wireless spectrum and increasing the channel capacity. However, the performance of the system is constrained by the wireless fading channel and the antenna array at the receiver and transmitter. In addition, the quality of the signal propagation is related to the characteristics of the wireless channel. Therefore, it is very important to establish an effective and accurate channel model. This paper mainly based on geometric space domain channel modeling and MIMO system performance analysis, mainly includes the following parts: first, This paper introduces the large scale fading and small scale fading when the signal is transmitted in the wireless channel, mainly introduces the types and characteristics of the two kinds of fading, and gives the corresponding channel model to explain. It also introduces the common channel models in detail: Gao Si fading model, Rayleigh fading model and Rice fading model. Secondly, a channel model which is more suitable to describe the macro cell mobile communication environment is proposed. Usually, in macro cell environment, the antenna at base station is higher than all buildings nearby to reduce the effect of multipath effect, but this is not the case, so a more accurate and effective channel model is established according to this condition. The scatterer is distributed by Gao Si, and the distribution of angle of arrival angle of Arrivalan AOAA, time of arrival time of Arrivalo toa) and Doppler frequency shift probability density are analyzed. The simulation results are compared with other models. The results show that the model is more suitable to describe the mobile communication environment of macro cell in the actual situation. Then, the above channel model is improved once more, and the mobile communication space environment is asymmetric. A more practical asymmetric spatial channel model is proposed, which can not only accurately describe the important space-time parameters of asymmetric channel in signal propagation environment, but also be used in channel performance simulation of MIMO receiving system. By analyzing the numerical simulation results of linear antenna array and circular antenna array, it is found that circular antenna array has more advantages. Then, a three-dimensional three dimensional spatial MIMO channel model suitable for indoor micro-cell mobile communication environment is proposed. In this model, there is no scatterer around the mobile station, which is regarded as the central origin, which is extended from the two-dimensional analysis to the three-dimensional spatial analysis, and the propagation characteristics of the arrival signal in the vertical plane are increased. The important space-time channel parameters of the spatial channel model in two different planes, such as the probability density function of AOA and TOA, are derived. The MIMO channel model can be applied to the mobile communication environment of indoor microcell, and provides a flexible and changeable model for the research of 3D spatial channel. Finally, based on the 3D spatial domain, In this paper, a new theoretical channel model is proposed. The theoretical analysis is complicated and the closed analytical formula is not easy to be obtained due to the nonuniform distribution of scatterers. This model can accurately describe the important space-time parameters of spatial channel in the environment of outdoor macro cell, and derive the probability distribution function of AOAOTOA. The probability distribution function of Doppler shift shift DSs in 3D space is derived. The simulation results show that the 3D channel model is better and more accurate than the two-dimensional channel model in describing the outdoor macro cell mobile communication environment.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

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