Precision of direction of arrival (DOA) estimation using novel three dimensional array geometries

Numerous methods for direction of arrival (DOA) estimation, used in smart antennas have been already reported in previous studies. The precision of DOA estimation depends on the choice of the algorithm and the geometrical configuration of the antenna array. In this work, the performance of new geometrical configurations, i.e. 2D with equal area and 3D with equal volume including circular, square, triangular, hexagonal and star geometries, with equal number of antenna elements, are examined and compared to each other to find the most proper geometry. Monte-Carlo simulations are performed to evaluate the DOA precision of the proposed arrays using the MUSIC algorithm. It is shown that in three cases of comparison including 2D geometries, 3D geometries and 3D rotated geometries, with the star and triangular configurations one achieves better resolution in DOA estimation. It is also revealed that the rotated configurations show lower estimation error compared to normal configurations.     

考虑互耦影响下的DOA估计算法

研究了考虑互耦情况下的DOA估计算法MUSIC算法。互耦改变了阵列响应矢量和接收信号相干矩阵的特征值结构,因此影响了DOA估计的精度,用矩量法计算了由半波振子阵列的单元之间的互耦,通过得到的阻抗矩阵来估计互耦的影响。最终给出了计算机仿真的结果。     

多径条件下均匀线阵DOA估计及互耦误差自校正

针对多径信道环境下存在互耦误差的均匀线阵,提出了一种联合波达方向估计及互耦 误差自校正算法。在不改变阵列互耦误差的条件下,首先利用虚拟阵列平移预处理方法,将 相干信源协方差矩阵恢复到满秩。进而利用互耦误差的对称Toeplitz特性,基于子空间原理 构造一代阶函数,采用秩损的方法得到互耦误差条件下的DOA估计及阵列互耦误差。数值仿 真结果表明,该算法具有良好的DOA估计性能与互耦误差自校正性能。     

Direction-of-arrival estimation in the presence of mutual coupling based on joint sparse recovery

A novel Direction-Of-Arrival (DOA) estimation method is proposed in the presence of mutual coupling using the joint sparse recovery. In the proposed method, the eigenvector corresponding to the maximum eigenvalue of covariance matrix of array measurement is viewed as the signal to be represented. By exploiting the geometrical property in steering vectors and the symmetric Toeplitz structure of Mutual Coupling Matrix (MCM), the redundant dictionaries containing the DOA information are constructed. Consequently, the optimization model based on joint sparse recovery is built and then is solved through Second Order Cone Program (SOCP) and Interior Point Method (IPM). The DOA estimates are gotten according to the positions of nonzeros elements. At last, computer simulations demonstrate the excellent performance of the proposed method.     

Direction-of-arrival and polarization estimation with uniform circular arrays in the presence of mutual coupling

A modified Root-MUSIC algorithm is proposed to estimate the directions-of-arrival (DOAs) and the polarization of plane waves, which impinge at a fixed elevation angle, using a diversely polarized uniform circular array (UCA). Special attention is devoted to the presence of mutual coupling effects in antenna arrays. By describing the electromagnetic characteristics on the basis of a phase-mode expansion for the open-circuit voltages and the mutual coupling matrix, the modified Root-multiple signal classification (MUSIC) algorithm takes mutual coupling effects into account by a limited number of phase modes. Finally, the efficiency of the new algorithm is verified based on synthetic antenna data.     

基于三维立体线阵的全方位DOA估计方法

本文基于3D立体线阵以及累量的灵活定义,实现了信号DOA的全方位估计,该算法不依赖于信号的具体结构,并构造了三个累量域DOA矩阵,通过对DOA矩阵的特征分解得到配对特征向量,从而获得信号DOA的全方位估计,该方法避免了2D或1D的谱峰搜索,仿真实验结果表明了这种方法的正确性。     

阵元间互耦条件下一维波达方向估计方法

该文在与波达方向(DOA)有关的阵元间互耦条件下,提出了一种新的自校准DOA估计方法,并给出了参数可辨识性的一个必要条件。该方法利用一维DOA搜索,无需估计互耦参数,避免了多维参数搜索和迭代过程。仿真实验结果表明,阵元间互耦参数和DOA估计存在模糊性。在其间存在互耦的阵元个数已知的条件下,可以得到正确的DOA估计结果。     

Compensation for the mutual coupling effect for the ESPRIT algorithm in single snapshot array processing

An effective method is introduced to compensate the effects of mutual coupling for the Estimation of Signal Parameter via Rotational Invariance Techniques (ESPRIT) direction finding algorithm in application of signal snapshot array processing.Changing the covariance matrix into a Teoplitz matrix can achieve high resolution in the Direction Of Arrive (DOA) estimation.How the mutual coupling affects the array antennas has been discussed and a new definition of mutual im- pedance has been used to characterize the mutual coupling effects between the array elements.Based on the new mutual impedance matrix,a practical method is presented to eliminate the effects of mutual coupling for ESPRIT in the single snapshot data processing.The simulation results show that, this new method not only properly reduces the effects of mutual coupling,but also maintains its steady performance even for weak signals.     

L-shaped array-based elevation and azimuth direction finding in the presence of mutual coupling

For two-dimensional (2-D) directions-of-arrival (DOA) estimation problem, both the mutual coupling and the failure in pairing can cause severe performance degradation. In this paper, a new elevation and azimuth direction finding algorithm is developed to overcome the above-mentioned two difficulties in the L-shaped array configuration. The key points of this paper are: (i) constructing several correlation matrices to blindly compensate the effect of unknown mutual coupling using the outputs of properly chosen sensors and (ii) deriving a rank-reduction propagator method to estimate elevation and azimuth angles so as to avoid pairing parameters. Simulation results are presented to validate the performance of the proposed method.     

L型阵列互耦条件下的二维波达方向估计

针对L型阵列,提出一种去互耦算法.该算法在L型阵列的两均匀线阵上分别取受互耦影响一致的阵元,则其理想导向向量可与互耦参数剥离,用其中一组阵元输出的协方差阵和两组阵元输出的互协方差阵构建矩阵,根据其传播算子构成的信号子空间和阵元导向向量张成同一空间以及均匀线阵的旋转不变特性得到两个与方向角和俯仰角相关的信息参量.在这两参量配对时,只需对包含信息参量的其中一个矩阵进行一次特征值分解以及简单的除法运算即可实现.理论和仿真表明,该算法无需谱峰搜索,只需一次特征分解,有效抑制了互耦影响,测量精度高.     

三维空间多天线相关性及互耦影响研究

针对三维传播环境下多天线系统空域相关性评估问题,首先将达波信号二维角度谱建模为更为通用的von Mises-Fisher（vMF）分布,并推导了不同阵列流型天线空域相关系数的解析式和近似表达式;然后分析互耦机理及其对接收信号矢量的影响,据此推导了互耦效应下天线空域相关性的闭式表达式,并给出了存在互耦的相关性与无互耦相关性之间的内在关系.仿真结果表明,本文推导的天线相关性表达式与数值计算结果非常吻合.另外,小角度扩展时,考虑互耦效应的天线空域相关曲线围绕着无互耦时的相关性曲线上下波动,且面型阵列具有更好的抗互耦能力.     

Directions of arrival estimation with planar antenna arrays in the presence of mutual coupling

Directions of arrival (DoAs) estimation of multiple sources using an antenna array is a challenging topic in wireless communication. The DoAs estimation accuracy depends not only on the selected technique and algorithm, but also on the geometrical configuration of the antenna array used during the estimation. In this article the robustness of common planar antenna arrays against unaccounted mutual coupling is examined and their DoAs estimation capabilities are compared and analysed through computer simulations using the well-known MUltiple SIgnal Classification (MUSIC) algorithm. Our analysis is based on an electromagnetic concept to calculate an approximation of the impedance matrices that define the mutual coupling matrix (MCM). Furthermore, a CRB analysis is presented and used as an asymptotic performance benchmark of the studied antenna arrays. The impact of the studied antenna arrays geometry on the MCM structure is also investigated. Simulation results show that the UCCA has more robustness against unaccounted mutual coupling and performs better results than both UCA and URA geometries. The performed simulations confirm also that, although the UCCA achieves better performance under complicated scenarios, the URA shows better asymptotic (CRB) behaviour which promises more accuracy on DoAs estimation.     

互耦条件下均匀线阵DOA盲估计

阵元间存在互耦时,经典的波达角(DOA)估计算法性能急剧下降甚至失效。针对互耦条件下均匀线阵DOA估计问题,该文提出一种基于盲源分离的DOA盲估计算法。首先,利用源信号的统计特性,由盲源分离方法估计广义阵列流形矩阵;然后,利用均匀线阵互耦矩阵带状、Toeplitz矩阵的特点,将DOA估计问题转化为多个可分离非线性最小二乘问题,由多个1维频域搜索得到DOA的估计。该算法无需高维搜索或多维迭代,对互耦自由度要求更低,互耦自由度未知时仍旧适用,稳健度高。数值仿真验证了该文算法的有效性。     

三维圆柱形电荷俘获存储器件的继续微缩对其性能的影响

本文详细地研究了关键尺寸的继续微缩对三维圆柱形无结型电荷俘获存储器器件性能的影响。通过Sentaurus三维器件仿真器,我们对器件性能的主要评价指标进行了系统地研究,包括编程擦除速度和高温下的纵向电荷损失及横向电荷扩散。沟道半径的继续微缩有利于操作速度的提升,但使得纵向电荷损失, 尤其是通过阻挡层的纵向电荷损失,变得越来越严重。栅极长度的继续微缩在降低操作速度的同时将导致俘获电荷有更为严重的横向扩散。栅间长度的继续微缩对于邻近器件之间的相互干扰有决定性作用,对于特定的工作温度及条件其值需谨慎优化。此外,栅堆栈的形状也是影响电荷横向扩散特性的重要因素。研究结果为高密度及高可靠性三维集成优化提供了指导作用。     

Characterization and modeling of RF substrate coupling effects in 3D integrated circuit stacking

This work addresses parasitic substrate coupling effects in 3D integrated circuits due to Through Silicon Vias (TSV). Electrical characterizations have been performed on dedicated test structures in order to extract electrical models of substrate coupling phenomena when RF signals are propagated in TSV. A good compatibility between RF measurements and RF simulations allows validating modeling tools for predictive studies. Next, parametric studies are performed in order to study impact of TSV design and materials on substrate coupling noise.     

相控阵三坐标雷达中显示补点器的设计

讨论了显示补点器的技术特点、视频补点处理的技术等 ,以及它们在相控阵三坐标雷达中的应用     

三维PDP放电过程数值模拟软件

介绍了三维PDP放电过程模拟软件，该软件可较真实地反映放电单元的实际情况，对放电性能进行优化设计，且具有通用性强、界面友好、使用方便、功能完善等特点。可对不同结构、不同气体成份、不同驱动电压及波形等情况进行计算。     

空间三维分层仿真在LTE无线网络规划优化中的应用

研究一种预测室外宏站对建筑物室内覆盖效果的方法。在LTE无线网络规划仿真中，如何考察室外宏站对建筑物室内的覆盖效果是一个值得考虑的问题。本文主要基于射线跟踪技术对不同高度的楼层进行仿真，然后综合分析各楼层的覆盖指标，基于一定判定标准分析室外宏站对某建筑物的覆盖情况，最后给出建筑物是否需要部署室分的建议。