Comparison of TDOA location algorithms with direct solution method

For Time Difference Of Arrival (TDOA) location based on multi-ground stations scene, two direct solution methods are proposed to solve the target position in TDOA location. Therein, the solving methods are realized in the rectangular and polar coordinates. On the condition of rectangular coordinates, first of all, it solves the radial range between the target and reference station, then calculates the location of the target. In the case of polar coordinates, the azimuth between the target and reference station is solved first, then the radial range between the target and reference station is figured out, finally the location of the target is obtained. Simultaneously, the simulation and comparison analysis are given in detail, and show that the polar solving method has the better fuzzy performance than that of rectangular coordinate.     

Asymptotic boundary conditions for finite element analysis ofthree-dimensional transmission line discontinuities

The finite element method is used to analyze open three-dimensional transmission line structures in the quasi-TEM regime. Starting from the general solution of the Laplace equation in spherical coordinates, a set of asymptotic boundary conditions are derived for three-dimensional quasi-static problems for a spherical outer boundary. The second-order boundary condition is generalized to a box-shaped outer boundary and implemented in the finite element method to solve the potential problem of a rectangular microstrip patch. Numerical results show that the asymptotic boundary conditions yield more accurate results than those obtainable with a perfectly conducting shield placed at the same location     

无源时差定位方程的半定松弛解法

针对基于到达时差量测的多站无源定位系统,提出了一种基于半定松弛的时差定位方程求解方法.该方法首先将关于目标位置估计的非凸二次优化问题转换成等价的非凸半定规划问题,然后通过秩1松弛得到一个凸优化问题,最后对松弛半定规划问题的最优解进行秩1近似,从而提取出最终的目标位置估计.计算机仿真结果表明这种松弛解法可以有效求解目标位置.     

基于调频广播无源定位的有效可定位区

基于调频广播无源定位实际相当于收发分置的双基地雷达,通过对有效可定位区定义的分析,从能量约束、误差约束两个方面着手,建立了基于调频广播无源定位有效可定位区的计算模型。运用栅格法求解模型,较好地解决了有效可定位区的绘制和估算问题。最后,对算法进行了仿真实验,分析了仿真结果。     

Application de l’étude de la diffraction par un réseau à la propagation dans les guides périodiques

The authors propose a method for the study of the propagation of an electromagnetic wave in a periodical guide, which follows that of the plane wave diffraction by a grating. The solution of the Maxwell’s equations under covariant form is calculated in a non-orthogonal system of coordinates, following the geometry of the problem. It leads to the search for eigenvalues and eigenvectors of a matrix which is characteristic of the coordinates and of the medium. For gratings, one has to solve an inhomogeneous linear system. In the case of a rectangular waveguide with meanders, the system becomes homogeneous, which allows the calculation of the dispersion condition.     

A three-dimensional FDTD algorithm in curvilinear coordinates [EMscattering]

The finite-difference time-domain (FDTD) algorithm for the solution of electromagnetic scattering problems is formulated in numerically defined generalized coordinates in three dimensions and implemented in a code with the lowest order Bayliss-Turkel radiation boundary condition expressed in spherical coordinates. It is shown that the algorithm is capable of accurately tracking the progress of a pulse of electromagnetic radiation through the curvilinear mesh generated by a body of revolution, the only problems occurring in the vicinity of the rotation axis, which represents a coordinate singularity. A simple method to deal with this singular line is presented and discussed, and its is shown that, at least for the test problem, this approximation is sufficient. The algorithm discussed is useful for the solution of the exterior problem in the presence of conductors and dielectrics with complicated shapes and electrical compositions, and for near-field problems such as cavity penetration problems. The far fields are obtained by replacing the scatterer with a virtual surface enclosing all sources     

适用于NLOS传播环境的几何定位方法

基于非视距传播(NLOS)的影响,移动通信环境中波达时间(TOA)的测量误差具有正偏置的特性,本文提出了一种简单的几何定位方法。该方法根据基站分布和TOA测量数据确定出若干个定位点,对这些点的坐标取平均值即得到移动台的位置估计。仿真结果表明,该方法能够有效提高NLOS传播环境下的定位精度,对LOS传播条件下的定位精度影响小。     

无线传感网中NLoS环境下的ToA/AoA改进混合定位算法(英文)

An improved hybrid Time of Arrival (ToA)/ Angle of Arrival (AoA) location algorithm by adopting Gauss-Newton iterative algorithm is proposed. It is with the advantage of fast convergence and combining with the grid-search-based method to optimize the initial object coordinates of the iteration, meanwhile, under the condition of small measurement errors caused by noises of ToA and AoA, the algorithm performance can be improved effectively. In the Non-Line-of-Sight (NLoS) environments of the Wireless Sensor N...     

双站基于角度和时差的近似无偏定位算法

联合角度（DOA）和时差（TDOA）信息对运动目标进行无源定位实质上是一种非线性估计问题。针对将非线性观测方程转化为伪线性方程会产生有偏估计的缺点,该文基于双站定位中获得的角度和时差信息,给出了一种对三维空间目标定位跟踪的近似无偏估计滤波算法,它只需要对一对矩阵束进行广义特征分解,即可获得目标坐标和速度的估计值。计算机仿真结果表明,相比有偏估计滤波算法,如伪线性卡尔曼滤波（PLKF）算法或者最小二乘（LS）算法,该算法具有更高的定位精度,并且当观测误差增大时,其优势更加明显。     

一种基于误差距离加权与跳段算法选择的遗传优化DV-Hop定位算法

针对Distance Vector-Hop (DV-Hop) 定位算法存在较大定位误差的问题,该文提出了一种基于误差距离加权与跳段算法选择的遗传优化DV-Hop定位算法,即WSGDV-Hop定位算法。改进算法用基于误差与距离的权值处理锚节点的平均每跳距离;根据判断的位置关系选择适合的跳段距离计算方法;用改进的遗传算法优化未知节点坐标。仿真结果表明,WSGDV-Hop定位算法的性能明显优于Distance Vector-Hop (DV-Hop) 定位算法,减小了节点定位误差、提高了算法定位精度。     

Two-channel constrained least squares problems: solutions using power methods and connections with canonical coordinates

The problem of two-channel constrained least squares (CLS) filtering under various sets of constraints is considered, and a general set of solutions is derived. For each set of constraints, the solution is determined by a coupled (asymmetric) generalized eigenvalue problem. This eigenvalue problem establishes a connection between two-channel CLS filtering and transform methods for resolving channel measurements into canonical or half-canonical coordinates. Based on this connection, a unified framework for reduced-rank Wiener filtering is presented. Then, various representations of reduced-rank Wiener filters in canonical and half-canonical coordinates are introduced. An alternating power method is proposed to recursively compute the canonical coordinate and half-canonical coordinate mappings. A deflation process is introduced to extract the mappings associated with the dominant coordinates. The correctness of the alternating power method is demonstrated on a synthesized data set, and conclusions are drawn.     

Method of regularisation for inverse of convolution of finite-length sequences

The problem of 'ill-posedness' for the case of the inverse of the convolution of finite-length discrete signals is examined. A method of regularisation that enables one to obtain a reasonable solution to such an inverse problem in introduced, and a new definition of the condition number is proposed. A simple example of application is presented.<>     

摄动条件下空间目标天基光学跟踪方法研究

该文针对摄动条件下的空间目标天基光学监视跟踪问题,引入UT变换和混合坐标系,在直角坐标空间内采用UT变换完成目标运动状态预测和预测协方差计算并考虑摄动因素影响,在修正球坐标空间内实现状态滤波更新,提出混合坐标SPKF跟踪方法,可避免EKF线性截断误差影响并增强跟踪滤波稳定性。仿真结果表明,在密集采样和稀疏测量条件下该方法在收敛性和稳健性上均具有优势。     

单站两坐标雷达空间目标跟踪新算法研究

在以常规卡尔曼滤波器为基础的各种跟踪算法中，要求精确的模型和噪声统计，但在实际问题中，大多数情况上述要求不能满足。本文给出了考虑初始条件不精确性的改进型卡尔曼滤波算法，并在引入速度量测信息的基础上，运用该滤波方法进行空间目标二维定位。蒙特卡洛仿真表明该方法降低了对模型精度的要求，在工程上是可行的。     

Definition of parameters values of sinusoidal signal,distorted by unknown pulses

In this paper a problem of definition of sinusoidal signals parameters distorted by unknown pulses is considered. It is supposed that shape, quantity and other parameters of pulses a priori unknown, but their total duration is less then an observation interval. It is given a criterion that this problem solution is achieved at the point of a minimum of a functional “duration residual” between known data and mathematical model.     

融合环境下IMS紧急呼叫业务技术及应用研究

分析了融合环境下IMS紧急呼叫业务实现中用户位置信息定义复杂化、位置信息获取方式多样化等特点。对业界提出的IMS紧急呼叫技术方案中支持终端和接入类型、位置信息的提供方式、紧急指挥中心/联动中心在网络中的连接方式等关键技术进行了研究,指出业界紧急呼叫技术在实际应用中存在的覆盖接入设备和终端不全面、对接入网改造大等问题。结合运营商IMS网络部署特点及终端接入的实际需求,对业界技术方案提出补充完善建议,提出满足固移融合需求的紧急呼叫业务系统实现方案。     

一种红外成像系统的畸变测试方法

红外成像系统图像畸变控制的良好与否对其能否在应用平台上发挥应有作用极为关键,因此在实验室内对红外成像系统的图像畸变进行测试、分析是极其必要的,本文提出了一种结合质心亚像素识别和精密测角的局部畸变测试方法,读取点靶在各个局部视场的质心变化并进一步计算即可得到畸变。采用该方法可以较好地解决点列质心法测试大视场系统操作性不高以及局部畸变法定位不够精确的问题,采用本方法对某型号红外成像系统进行了局部畸变测试,取得了与理论较为相符的测试结果,其相对畸变测试误差不超过0.02%,可以很好地满足红外成像系统的畸变测试需求,并对成像系统性能进行评估,有效反馈图像畸变对红外成像系统探测能力的影响。     

A location-based method for restricting the flooding DoS effect in WLANs

Abstract

WLANs are prone to flooding denial-of-service (DoS) attacks. Present research work proposes a novel method to enhance WLAN security by restricting flooding DoS effect on the access point (AP). Each node in the proposed method listens transmission of other neighbouring nodes and sends at regular interval a linked list to AP, containing the identifiers (IDs) of all nodes from which it hears. AP stores the linked list information and runs location-based coordinate calculation (LBCC) algorithm. LBCC finds the expected coordinates of each node and probable location area with the expected coordinates as centre. Flooding DoS attack by the attacker is restricted at the AP using node’s probable location area. The method is validated by simulation experimentations with varying topologies. Further, geometrical analysis of the method is also provided.     

Solution of the nonlinear eigenvalue boundary-value problem for tm electromagnetic waves propagating in a Kerr-nonlinear layer by means of the cauchy problem method

The problem of propagation of TM electromagnetic waves in Kerr-nonlinear layer is considered. The problem is reduced to the solution of a nonlinear eigenvalue boundary-value problem for a system of two ordinary differential equations. A numerical method is proposed for solving the considered eigenvalue boundary-value problem. It is shown that the proposed method makes it possible to investigate more complicated types of nonlinearity. Numerical results are reported. The method is compared to another known technique and to the linear case.     

Energy-aware infrastructure placement for secure communication

Physical layer security is attracting more and more attention due to its inherent channel properties, while the increasing computing ability is not the obstacle for the traditional encryption any longer. In this paper, we study the base station (BS) and relay station (RS) placement problem in a cooperative secure communication system. Moreover, the system energy consumption problem also has been considered, and an energy-aware infrastructure placement for secure communications (EIPSC) scheme is proposed. Based on the analysis results of different candidate position of the security performance, location of the BS is determined and some imperative RSs are placed to guarantee the eavesdropped subscribers' secure communication. To decrease the system energy consumption, we propose a conception of sharing set of RS in order to place the RS as few as possible. During the BS and RS placing as well as adjusting procedure, renewable energy is also been considered to reduce dirty-energy consumption. Through computational experiments, we show our proposed algorithm can get better performance than the traditional placement algorithm not only at the system security guarantee but also at the system energy saving.