FOC-MUSIC与MUSIC算法的稳健性对比分析

分析比较了阵元存在误差时基于四阶累积量的MUSIC方法（FOC-MUSIC）和基于协方差的MUSIC方法对波迭方向的估计性能，给出了大样本情况下估计误差方差的统一公式，基于这个公式从理论上分析了前一种方法的稳健性优于后一种的原因。仿真结果表明；文中提出的理论比较结果与实际仿真结果吻合，在存在幅相误差的情况下，FOC-MUSIC算法的稳健性确实优于基于协方差的MUSIC算法。     

再论循环码的周期分布

本文揭示了循环码的周期分布与其对偶码的周期分布的关系，给出了一般循环码及其对偶码内无内周期码字的精确计数公式。     

模型误差对非圆信号测向MUSIC算法性能的影响

近年来,针对非圆信号的测向算法已陆续提出,对这些算法的渐近性能及Cramer-Rao界的分析也已见报道,但仍未涉及模型误差对此类算法影响的分析.本文概括介绍了用于非圆信号测向的MUSIC(Multiple Signal Classification)算法,对其空间谱函数进行一阶泰勒展开,得到了测向误差的表达式,从而求得测向均方误差统计意义上的表达式.仿真实验验证了推导的正确性,并由理论结果分析了模型误差条件下测向误差与角度间隔和非圆相位差的关系.     

On 2-D Direction-of-Arrival Estimation Performance for Rank Reduction Estimator in Presence of Unexpected Modeling Errors

The rank reduction estimator (RARE) is one kind of autocalibration method used in the presence of sensor errors. It demonstrates high accuracy of direction-of-arrival (DOA) estimation in the absence of multidimensional search or iteration. However, its estimation performance is affected by “unexpected modeling errors.” There is a lack of research regarding the performance of 2-D RARE estimation, although 2-D RARE estimation is extensively employed in applications. This paper presents a theoretical derivation for the closed-form expression of the mean square error (MSE) of 2-D RARE estimation under the influence of small unexpected modeling errors in the first order analysis. First, three definitions of 2-D joint direction-finding success are introduced, in order to establish the criterion for estimate performance. Then corresponding theoretical formulas for three probabilities of direction-finding success are given with the circularly Gaussian assumption of unexpected modeling errors, and their relations are discussed. Finally, the results of simulations utilizing our analysis method are demonstrated, verifying the effectiveness of the MSE expression and the formulas for probabilities of success. Therefore, our first order approximation provides a good prediction of the necessary calibration accuracy in the presence of unexpected modeling errors in order to help RARE meet an expected performance specification.     

Probability of resolution of the MUSIC algorithm

The MUSIC algorithm is well known for its high-resolution capability, and various aspects of its statistical performance have been investigated. However, rigorous asymptotic analysis of one of its most important performance measures, the probability of resolution, is not available yet. We analyze the probability of the MUSIC algorithm resolving two spatially separated signal sources in the context of array processing. By formulating the resolution problem in the framework of statistical decision theory and directly determining the probability density function (PDF) of the indefinite and singular quadratic form that defines the resolution event, we arrive at an exact asymptotic formula for the probability of resolution. This is accomplished by a multistep procedure. Computer simulations have been performed to confirm the validity of the theory     

阵列模型误差影响下ESPRIT算法的二阶性能分析

 针对阵列模型误差扰动的影响,该文对ESPRIT算法的方位估计性能进行二阶性能分析(即忽略模型误差扰动量的三次及以上各项).与经典分析方法(即一阶分析方法)相比,文中的性能分析方法能够在模型误差扰动较大的情况下提高性能预测精度.此外,文中的理论推导不仅针对阵列流形失配的情况,还针对阵元噪声模型失配的情形.数值实验表明:在较大模型误差的条件下,文中的二阶性能分析方法能够提高对ESPRIT算法的性能预测精度.     

存在近场辐射源情况下的阵列流形建模及分辨性能分析

当辐射源位于天线阵列的近场区域时,信号波阵面在天线阵列的孔径渡越无法忽略,此时电磁波信号到达阵列的波前需要用球面波模型进行描述。本文针对这种情况,研究了传感器阵列的一项固有属性——近场阵列流形,首先构建了任意N元阵列的近场阵列流形数学模型,其次利用微分几何对近场阵列流形的局部特性进行了分析,推导出了近场阵列流形弧长和一阶曲率的数学表达式,并利用这两种局部特性参数分析了近场辐射源参数估计的精度及分辨性能。     

On Probability Density for Modeling Video Traffic

Accurate models for variable bit rate (VBR) video traffic need to allow for different frame types present in the video, different activity levels for different frames, and a variable group of pictures (GOP) structure. The temporal as well as the stochastic properties of the trace data need to be captured by any models. We propose some models that capture temporal properties of the data using doubly Markov processes and autoregressive models. We highlight the importance of capturing the stochastic properties of the data accurately, as this leads to significant improvement in the performance of the model. In order to capture the stochastic properties of the traces, the probability density function of the trace data needs to be accurately modeled. Hence, the focus of this paper is on creating autoregressive processes with arbitrary probability densities. We relate this to work in wavelet theory on the solutions to two-scale dilation equations. The performance of our model is evaluated in terms of the stochastic properties of the generated trace as well as using network simulations.     

阵列模型误差条件下直接定位性能分析及偏差修正方法

相比于常规的"参数估计+位置解算"两步定位模式，直接定位（DPD）算法具有定位精度高、分辨能力强等诸多优势.但是，DPD算法的性能受到阵列模型误差的影响.本文通过一阶Taylor级数展开，定量推导出模型误差条件下基于多重信号分类直接定位算法（MUSIC-DPD）的定位误差，从定位误差的表达式中可以发现辐射源的真实位置和MUSIC-DPD所得的有偏位置估计之间存在一种非线性关系，但这关系在实际条件下无法精确表示.为此，本文提出一种基于多层感知器（MLP）神经网络的直接定位偏差修正方法，该方法能够直接学习由阵列模型误差引起的定位偏差的规律，有效地修正由阵列模型误差导致的直接定位偏差.     

Simulation of MC-CDMA in the Presence of Timing Errors

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Performance of MPEG Codecs in the Presence of Errors

MPEG is emerging as a major international standard for applications in compressed video storage, transmission, and interactive communications. MPEG will be used in applications which involve imperfect channel conditions or storage defects. This work studies the effects of different types of errors on MPEG-encoded bit streams and possible approaches to minimize such effects. The applicability and tradeoff of forward error correction, block interleaving, and error concealment to MPEG-encoded bit streams are also investigated.     

On the constrained MUSIC technique

A constrained MUSIC technique, recently proposed for bearing estimation, is shown to be a version of the beam-space MUSIC. This observation places the constrained MUSIC in a class of bearing estimators whose statistical performance is well understood     

自适应通道均衡在MUSIC空间谱及分辨率中的应用

高分辨率参数估计算法MUSIC对系统误差比较敏感。文中分析了接收阵元间通道失配对MUSIC空间谱的影响。计算机仿真表明自适应通道均衡可以极大地提高MUSIC空间谱峰值及目标分辨力     

Performance Analysis of MC-CDMA in the Presence of Carriers Phase Errors

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IrBurst Modelling and Performance Analysis in the Presence of Transmission Errors

IrBurst is a session/presentation layer protocol dedicated for high speed large volume information transfer over IrDA links. The protocol is developed by IrDA in order to complement the existing protocol OBEX which is best suited for small files. This paper presents a mathematical model for IrBurst over the IrDA protocol stacks taking into account the presence of bit errors and multiple simultaneously applications. The performance of IrBurst is examined considering TinyTP buffer sizes and the number of IrBurst application connections as parameters. The contribution of this work is to develop a mathematical model for IrBurst, investigate the compatibility of IrBurst to low layer protocols, as well as providing suitable design guidelines for IrDA devices for high performance of IrBurst. Pi Huang received the B.Sc. degree in Electrical and Electronic Engineering from University of Central Lancashire, U.K., in 2001, the M.Sc. degree in Telecommunications from University College London, U.K., in 2002 and the Ph.D degree in the Personal Wireless Networks and Outdoor Optical Links from Bournemouth University, U.K., in 2006. He is currently working in wireless solution division of British Telecom. His research focuses on performance modelling and analysis as well as discrete-event simulation of wireless communication protocols and wireless communication networks. He has published over 20 papers in the areas of wireless communications. Anthony C. Boucouvalas has worked at GEC Hirst Research Centre, and became Group Leader and Divisional Chief Scientist until 1987, when he joined Hewlett Packard (HP) Laboratories as Project Manager. He joined Bournemouth University in 1994 and became a Professor in Multimedia Communications in 1996, and in 1999 became Director of the Microelectronics and Multimedia Research Centre. His current research interests span the fields of wireless communications, optical fibre communications and components, multimedia communications, and human-computer interfaces, where he has published over 200 papers. He has contributed to the formation of IrDA as an industry standard and he is now a Member of the IrDA Architectures Council. He is a Fellow of Fellow of the Royal Society for the encouragement of Arts, Manufacturers and Commerce, (FRSA) and a Fellow of IEE, (FIEE). In 2002 he became a Fellow of the Institute of Electrical and Electronic Engineers (FIEEE), for contributions to optical fibre components and optical wireless communications. He is an Editor of numerous Journals and in the Organising committee of many conferences.     

CSIT获得中带有错误呈现的鲁棒THP设计

In this paper, a robust THP is proposed for broadcast channel in multi-user multi-input multi-output (MU-MIMO) system, in which the channel uncertainty caused by feedback delay and mobile speed is taken into account. In order to acquire the imperfect channel state information at transmitter (CSIT), a dynamic CSIT model is introduced where the channel temporal and spatial correlations are considered. By utilizing the unchanged channel statistics and accurate outdated feedback channel information jointly, the...     

幅相误差对修正MUSIC算法测向性能的影响与分析

首先阐述了阵列信号处理中广泛采用的修正MUSIC算法原理，并推导了天线阵元幅相误差条件下的修正MUSIC算法，重点分析了阵元幅相误差对修正MUSIC算法测向性能的影响。最后以均匀线阵为例进行了仿真，计算机仿真结果表明，阵元幅相误差严重影响着修正MUSIC算法的测向性能，因此在应用修正MUSIC算法进行来渡方向估计的时候，必须考虑阵元幅相误差的影响。     

一种检测噪声中正弦信号的SVD方法

本文以对观测数据矩阵直接进行奇异值分解为基础提出了一种正弦检测的新方法.与其它方法相比,本文方法具有噪声特性较好,能处理较短数据序列以及较好的计算稳定性等优点,能够有效地消除正弦观测序列中的噪声干扰,得到较好的估计结果.仿真实验证明了本文方法的正确性和有效性.