波束成形在水声定位中的应用

由于水声环境的复杂性,存在着海洋噪声,海水吸收,多途效应等一系列问题,水声定位的精度一直很难提升.给出了水声定位的系统结构框图,采用了时延波束成形技术对天线阵列接收信号进行滤波处理.仿真结果表明定位信号经过时延波束成形后,波束图就会在所需的方向上得到加强,而在其他方向上减弱,达到了增强信号、抑制噪声的效果.模拟了东海海域环境对水声定位系统做了仿真,未经过波束成形的接收阵输出信噪比很小,无法判断来波的方向.经过波束形成处理后,阵列的输出信噪比增大,在信号源的方向呈现明显的输出峰值,测向效果得到显著改善.     

基于数字波束形成的多目标测控

针对单站多目标同时测控中存在的问题,提出将数字波束形成技术应用于单站测控系统天线中,以更好实现对多目标的同时测控。针对多目标测控对天线系统的特殊要求,并结合数字波束形成技术自身的特点,分析了数字波束形成技术在实现全空域波束扫描、大型阵列波束形成和多目标跟踪时存在的3方面突出问题,并提出了解决的初步思路和方向。分析表明,采用数字波束形成技术的天线具有诸多优势,其在对多目标测控中具有广阔的发展前景。     

LTE/LTE-A MIMO原理与测试

正1概述天线技术和信号处理技术的发展,也让越来越多的人意识到通过多天线技术实现传输速率的增加是一种有效方式。MIMO(mutiple input mutiple output,多输入多输出)技术应运而生,它通过采用空时编码(STC),利用多天线阵列实现空间分集、复用或者波束赋形,在有限的带宽内极大的提高了频谱效率。因此,     

上海电网应用传送多协议标签交换技术的探讨

多业务传输平台(MSTP)网络已不能适应上海电网信息数据量迅速增长的通信需求.简要地介绍和分析了上海电力光传送网络现状以及传送多协议标签交换(T-MPLS)技术的特点和优点,同时探讨了T-MPLS技术在上海电力中应用方案.     

波束域相位中心互相关DOA估计方法

为提高多波束测深声呐回波到达角度(DOA)的估计性能,将三排阵测深侧扫声呐的相位中心互相关技术与多波束测深声呐的波束形成技术相结合,提出了一种新的波束域相位中心互相关DOA估计方法;并将该方法与传统相位差测向方法进行了比较,且推导出了两者的数学表达式;通过理论分析和仿真研究指出新方法能同时获得较大的相位非模糊区间和较低的DOA估计误差,有效提高了回波DOA的估计性能;对湖上试验数据的处理结果进一步表明该方法具有工程实际应用的有效性和可行性。     

多波束测深系统与侧扫声呐在水电站坝前淤积测量中的应用

水电站作为重要的水工建筑物,其在长期水力作用和环境因素下,坝前很容易淤积泥沙、木头等大型垃圾,这对水电站大坝的安全造成了巨大隐患.拟使用多波束测深系统进行水电站坝前淤积的全覆盖三维水下地形图的测量并利用侧扫声呐测量技术印证上述地形图量测结果的合理性.多波束测深系统与侧扫声呐技术生成的三维水下地形图、水下二维影像能够客观...     

混合波束赋形技术在4G通信系统中的性能研究

首先对常见的4G无线通信系统,描述了混合型的波束赋形算法,混合波束赋形技术是介于长期和短期波束赋形之间,最佳接近于Nrx=1.对于任意一个终端而言,每个RB的瞬时信道类似于单层波束赋形中的情况,一个特征值分解能够应用于瞬时或平均信道相关矩阵.波束赋形传输也能够沿着信道最强的方向传输所有可获得的功率(通过相关矩阵的显性特征向量可实现).接着对混合波束赋形技术做了一个软件设计实现方案,包含上行链路的SRS合路器和下行链路的物理层设计.最后,对于不同的算法性能指标给出了详细的仿真,得到了一些技术结论.     

射频识别技术在电力物资仓储管理中的应用

论述了射频识别技术(RFID)系统的组成及工作流程,指出了RFID技术的先进性,并针对当前吉林电力仓储管理的现状,提出了一种基于RFID技术的仓储管理方案,通过与企业资源计划管理(ERP)系统相连接,使电力仓库真正实现物资收发存储的高效运转.     

基于RPR的MSTP体系结构和MPLS VPN技术在电力城域网中的应用

讨论电力城域网的构架和需求,分析电力城域网建设面临的压力,重点论述了基于弹性分组环(RPR)的多业务传送平台(MSTP)体系结构和多协议标签交换虚拟专用网络(MPLS VPN)技术,两者相结合的组网方案在电力城域网中的应用具有无可比拟的优势,是向未来智能光网络演进的可行方案.     

基于LED的可见光MISO定位系统中波束成形的研究

由于可见光通信技术的能耗小且无电磁干扰等特点,该技术已越来越多地被运用到室内可见光定位系统中。但是,当定位目标接收到来自多个LED发送的位置信息时,受系统设备、传输路径或者多路定位信号本身等引入的系统延迟的影响,定位精度会大大降低。我们通过系统仿真和实验首次发现,由于系统延时的存在,接收信号的强度会发生波动。在多输入单输出(MISO)系统中,我们对在不同条件下的系统延时进行补偿,通过比较系统的误码率发现波束成形技术会明显提高系统定位精度。     

Multi-user MIMO systems: the future in the making

Very few technologies have had as much impact on the trajectory of evolution of wireless communication systems as multiple input multiple output (MIMO) systems. MIMO systems have already been employed in the existing 802.11n and 802.16e standards resulting in a huge leap in their achievable rates. A relatively recent idea of extending the benefits of MIMO systems to multi-user scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G. Although substantial research has been done on the theoretical front, recent focus is on making multi-user MIMO (MU-MIMO) practically realizable. It offers an enormous scope for further research in the coming years. As in the case of any evolving technology in communication systems, the literature concerning MU-MIMO systems involves complex mathematical analysis, making it difficult for an ordinary reader to comprehend. This article aims at giving an insight into MU-MIMO systems---its concept, fundamentals, and trends including an overview of important research results. It is intended at giving a good start to amateurs interested in being part of the community that shapes the future of wireless systems.     

Neutralizing interferences in two‐hop amplify‐and‐forward MIMO relay systems

In this paper, we present the interference neutralization technique for two‐hop multiple‐input multiple‐output (MIMO) relay systems. It enables multiple MIMO transmitters (sources) to simultaneously transmit independent data streams to their MIMO receivers (destinations) without mutual interferences, thereby improving spectral efficiency of the systems. To neutralize the mutual interferences using multiple amplify‐and‐forward (AF) MIMO relays, we establish the sufficient condition for the antenna configuration in the MIMO relay networks, and provide a filter design technique for the AF MIMO relays. The proposed method increases sum rates of the systems linearly with the number of transmitters participating in simultaneous transmission. To improve the sum rates further, this method is combined with transmit power allocation using the water‐filling algorithm. In addition, it is shown that by employing the minimum number of relays required to meet the sufficient condition, the system cost for the proposed method can be reduced without compromising the sum rate performance severely. Finally, simulation results successfully demonstrate that by exploiting radio resources such as frequency and time efficiently, the proposed method achieves a higher sum rate than the existing techniques based on interference avoidance. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

相关无线光MIMO系统的信道容量

空间相关性是制约无线光多输入多输出(MIMO)系统性能的主要因素之一。结合OOK调制技术,建立了相关无线光MIMO系统的信道模型,推导了不同相关机制下无线光MIMO系统的平均信道容量的解析式,分析了其中断性能。采用仿真实验分析了对数正态衰落信道中,空间相关性对均匀圆阵光MIMO系统的平均信道容量和中断信道容量的影响。结果表明,空间相关性的存在使得无线光MIMO系统的平均信道容量减小,中断概率增大;同时完全相关对于系统性能的影响较部分相关而言更为严重。     

MIMO systems with antenna selection

Multiple-input-multiple-output (MIMO) wireless systems are those that have multiple antenna elements at both the transmitter and receiver. They were first investigated by computer simulations in the 1980s. Since that time, interest in MIMO systems has exploded. They are now being used for third-generation cellular systems (W-CDMA) and are discussed for future high-performance modes of the highly successful IEEE 802.11 standard for wireless local area networks. MIMO-related topics also occupy a considerable part of today's academic communications research. The multiple antennas in MIMO systems can be exploited in two different ways. One is the creation of a highly effective antenna diversity system; the other is the use of the multiple antennas for the transmission of several parallel data streams to increase the capacity of the system. This article presented an overview of MIMO systems with antenna selection. The transmitter, the receiver, or both use only the signals from a subset of the available antennas. This allows considerable reductions in the hardware expense.     

MIMO空时处理技术在移动通信系统中的应用

对多天线MIMO技术在3G/LTE移动通信系统中的应用进行了深入分析与归纳总结。首先对比分析了WCDMA与CDMA2000系统中的MIMO技术的基本结构与原理。然后介绍了LTE系统中的MIMO模式及其原理。最后简要说明了多用户MIMO的基本概念,指出MIMO技术的未来发展方向。     

Fixed-time adaptive neural tracking control for a class of uncertain multi-input and multi-output nonlinear pure-feedback systems

This study examines the fixed-time adaptive neural network tracking control problem for a class of unknown multi-input and multi-output (MIMO) nonlinear pure-feedback systems. The introduction of the radial basis function resolves uncertain problems of unknown MIMO systems. The mean value theorem is introduced to overcome the controller design problem attributed to the nonaffine structure in pure-feedback systems. Moreover, a novel fixed-time virtual controller and an actual controller are designed to solve the issue of previous single-input and single-output and MIMO systems that have no solution in the negative domain and at the origin in finite- and fixed-time controls. Furthermore, a design method is proposed. The final designed controller ensures that all signals in the system are bounded. Simulation experiments show that the designed fixed-time controller facilitates smaller tracking error of the system compared with other finite- or fixed-time controllers. Furthermore, the selection of appropriate design parameters allows the tracking error to converge on a small neighborhood of the origin in a fixed time.     

Computing dominant poles of power system multivariable transfer functions

This paper describes a numerical linear algebraic algorithm to compute the dominant poles of multi-input-multi-output (MIMO) high-order transfer functions. The results presented are related to the study of electromechanical oscillations in large electrical power systems, but the algorithm is completely general. The computed dominant poles may then be used to build modal equivalents for MIMO transfer functions of large linear systems, among other applications.     

Multiple-antenna communication systems: an emerging technology

A recent development in wireless communications is the application of multiple-input multiple-output (MIMO) systems to radio communications via use of multiple antennas. In order to investigate the technologys potential, an experimental MIMO system containing two four-element antenna arrays (4x4) has been developed at the University of Alberta. The system is used to obtain MIMO channel measurements in a typical indoor office environment in the ISM band (902-928 MHz). Measurement campaigns have been performed using different antenna spacings and two different types of antenna: half-wavelength (lambda/2) centre-fed dipoles and dual-polarized patches. The measurements are used to calculate channel capacities for an indoor 4x4 MIMO system. The measurements confirm the high capacity potential of a MIMO channel, with ergodic capacity of approximately 21 bits per channel use available with either antenna type at a signal-to-noise ratio of 20 dB if the antenna element separation is lambda/2 or larger. An introduction to basic MIMO theory, a discussion of the University of Alberta wireless MIMO testbed, and observations regarding the measured indoor MIMO channel are presented in the paper.     

Analyzing control system robustness

We have presented mathematical connections among three stability criteria: (1) the Nyquist stability criterion for SISO systems; (2) the small gain theorem for unstructured perturbations in MIMO systems; and (3) the structured singular value for structured perturbations in MIMO systems. This connection can provide an intuitive understanding of MIMO stability analysis using singular values for those who have had prior exposure to the Nyquist stability criterion. Singular value techniques have been extended beyond the stability analysis presented here to performance analysis and robust control system design. This approach has been successfully used for many control problems, including a magnetically levitated train, helicopter control, aero-engine control, power conversion, active sound control, aircraft control, flexible space structure control and distillation process control. In the twentieth century, control theory evolved from classical control to modem control to optimal control to intelligent control. This evolution should continue and robust control (using the singular value techniques discussed here) will become more common in practice