大规模天线系统信道测量方法与空间相关性研究

发布时间：2018-06-02 22:26

本文选题：大规模天线系统 + 宽带信道测量　；参考：《北京交通大学》2017年博士论文

【摘要】：无线移动通信的发展深刻改变了人们的工作与生活方式。随着移动互联网和物联网等新兴应用不断兴起,无线流量呈现爆炸性增长,给第5代移动通信系统(5G)带来巨大挑战。作为5G的关键使能技术之一,大规模天线技术在基站侧使用数十甚至上百根天线利用相同的时频资源为多达数十个用户提供服务,具有高频谱效率、高能量效率和高可靠性等突出优势,能够满足未来高速移动通信需求。无线信道特性对大规模天线系统设计与性能评估至关重要。信道估计、天线选择和信道状态信息回传等算法均可利用基站阵元信道相关性进行优化,而预编码方案的复杂度与多用户信道相关性直接相关。因此,大规模天线系统中阵元和用户信道相关性研究具有重要意义。国内外已在此方面做了大量研究工作,但是仍然存在以下局限:1)在信道测量系统与场景方面,现有信道测量系统多采用商用信道测量仪器,或者利用信号发生器、信号分析仪及矢量网络分析仪等多台商用设备搭建测量系统,高昂的成本限制了信道测量活动的广泛开展;同时,现有信道测量场景多集中于室外,室内热点场景尚未得到充分研究。2)在阵列维度上信道相关衰落特性研究方面,多数优化算法仍然使用传统阵元相关模型,它们基于平面波假设获得,在大规模天线中的适用性需要更多实测验证;此外,视通场景中大规模天线阵列维度上信道空间连续性和随机性需要进一步建模分析。3)在多用户信道相关性研究方面,信道矩阵特征值扩展和条件数等表征参数存在一定局限性;同时,实际系统参数与多用户信道渐近正交性的关系缺乏数学模型进行定量描述。本文综合利用实际信道测量、系统仿真和理论分析建模等方法,研究实际无线场景中大规模天线系统的信道空间相关性。论文主要包括以下内容与贡献:1)基于多子频段切换的宽带无线信道测量方案设计、实现、校准与性能验证。本文提出的宽带信道测量方法在一个测量周期内连续探测多个相邻子频段从而成倍扩展测量带宽。此方法相比逐点扫频可以显著降低测量时间,对于低速移动信道尤为适用。同时,此方法无需使用高速宽带硬件,成本与实现复杂度较低。测量系统基于软件无线电平台实现,利用本文提出的系统校准方法,可以有效消除系统硬件的影响。通过多径信道仿真、有线信道和无线信道实测,验证了此方法的有效性。2)大规模天线阵列维度上信道衰落的自回归滑动平均(Auto-Regressive Moving Average, ARMA)建模,并利用莱斯K因子的ARMA模型改进了视通场景的相关信道模型。本文将线性大规模天线阵列中不同阵元的接收信号功率和莱斯K因子变化序列作为分析对象,使用ARMA模型分别进行建模。利用K因子的ARMA模型,提出了基于变化K因子的相关信道模型,以反映阵列维度上直达径与反散射径相对强度变化的空间连续性与随机性。3)大规模天线阵列中阵元信道相关系数分析与拟合建模。利用不同场景的实测数据,分析多种现有阵元相关模型在不同空间维度、不同房间尺寸条件下的适用性。垂直面内,由于天线增益方向性与环境的影响,阵元相关系数随阵元间隔增加呈现明显的振荡衰减。针对此特殊规律,本文提出了一种负指数衰减余弦模型对其进行有效拟合。4)多用户信道渐近正交性理论分析,并利用实测数据建立了对应的经验公式。本文通过理论推导得到了多用户大规模天线系统容量的上限值,然后利用实际信道容量与其上限值的比值衡量多用户信道正交性。利用不同场景和不同系统配置下的实测数据,建立了多用户信道渐近正交性与系统参数的经验公式。此经验公式可以定量分析不同系统参数对信道容量的影响,对系统设计与性能评估具有实际参考价值。
[Abstract]:The development of wireless mobile communication has greatly changed people's work and life style. With the rising of new applications such as mobile Internet and Internet of things, the explosive growth of wireless traffic brings great challenges to the fifth generation mobile communication system (5G). As one of the key enabling techniques of 5G, the use of large-scale antenna technology on the base station side Ten or even hundreds of antennas provide services for up to dozens of users with the same time and frequency resources. It has the advantages of high frequency spectrum efficiency, high energy efficiency and high reliability. It can meet the needs of high speed mobile communication in the future. The characteristics of wireless channel are very important to the design and performance evaluation of large-scale antenna systems. Channel estimation, antenna selection. The algorithm of selection and channel state information return can be optimized by channel correlation of base station, and the complexity of the precoding scheme is directly related to the correlation of multiuser channel. Therefore, the research on the correlation of array element and user channel in large-scale antenna system is of great significance. There are still the following limitations: 1) in the channel measurement system and the scene, the existing channel measurement systems mostly use commercial channel measurement instruments, or use signal generator, signal analyzer and vector network analyzer to build measurement systems, and high cost restricts the extensive development of channel measurement activities; at the same time, The existing channel measurement scenes are mostly outdoors, and the indoor hot scenes have not been fully studied in.2). Most of the optimization algorithms still use the traditional element correlation model, which are based on the plane wave hypothesis, and the applicability of the large-scale antenna needs more measurement and verification. The continuity and randomness of the channel space on the dimension of the large antenna array in the visual scene need further modeling and analysis of.3). There are some limitations in the characterization parameters such as the eigenvalue extension and the condition number of the channel matrix in the study of the multi-user channel correlation; and the relationship between the actual system parameter and the asymptotic orthogonality of the multi-user channel is lack. This paper makes a quantitative description of the mathematical model. In this paper, the channel spatial correlation of the large-scale antenna system in the actual wireless scene is studied by means of practical channel measurement, system simulation and theoretical analysis modeling. The main contents and contributions of this paper are as follows: 1) the design of broadband wireless channel measurement scheme based on multiband switching and implementation, Calibration and performance verification. The wideband channel measurement method proposed in this paper can continuously detect multiple adjacent subbands within a measurement period to multiply the measured bandwidth. This method can significantly reduce the measurement time compared to the point by point frequency sweep, especially for the low speed mobile channel. At the same time, this method does not require high speed broadband hardware, and the cost of this method is not necessary. The system is based on the software radio platform and the system calibration method proposed in this paper can effectively eliminate the influence of the system hardware. Through multipath channel simulation, wired channel and wireless channel measurement, the validity of the method is verified.2) the autoregression of the channel fading on the large antenna array dimension. The Auto-Regressive Moving Average (ARMA) model is modeled and the correlation channel model of the visual scene is improved by using the ARMA model of the LES K factor. In this paper, the receiving signal power of different array elements and the change sequence of the LES K factor in the linear large-scale antenna array are used as the analysis object, and the ARMA model is used for modeling. In the ARMA model of the sub, a correlation channel model based on the variable K factor is proposed to reflect the spatial continuity and randomness of the relative intensity of the direct and backscattering paths in the array dimension. The correlation coefficient analysis and fitting modeling of the array elements in the large antenna array are modeled and modeled. A variety of existing array elements are analyzed by using the measured data of different scenes. The applicability of the model in different space dimensions and room size conditions. In vertical plane, because of the antenna gain direction and the influence of the environment, the correlation coefficient of the array element presents obvious oscillation attenuation with the increase of the array element interval. In this special law, a negative digital attenuation cosine model is proposed for the effective fitting of.4). The asymptotic orthogonality of the user channel is analyzed, and the corresponding empirical formula is established by using the measured data. The upper limit of the capacity of the multiuser large-scale antenna system is derived by theoretical deduction. Then the multiuser channel orthogonality is measured by the ratio of the actual channel capacity to the upper limit value. The different scene and different system configuration are used. The empirical formula for the asymptotic orthogonality and system parameters of multiuser channels is established under the measured data. This empirical formula can quantitatively analyze the influence of different system parameters on the channel capacity, and has a practical reference value for the system design and performance evaluation.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN919.3

【参考文献】