一种基于端到端测量的路径性能参数估计算法

现有的网络性能估计技术不能实现对路径容量和可用带宽的同时测量。该文通过对存在拥塞链路的路径作随机分析,得到了一种对路径可用带宽的近似估计式,并通过对Kapoor(2004)中的方法进行改进, 提出了一种基于端到端的可以同时对单拥塞路径的容量及可用带宽进行估算的算法。在较准确估算路径容量的同时,达到了用同一组样本实例同时估计路径容量和可用带宽的目的。仿真验证了算法的有效性和准确性。     

Energy efficient routing with delay guarantee for sensor networks

The paper presents a routing algorithm that maximizes the lifetime of a sensor network in which all data packets are destined for a single collection node. Lifetime is maximized by adjusting the number of packets traversing each node. The adjustment is carried out by transmitting over alternative routes. The first part of the paper assumes that the worst case delay resulting from energy efficient routing is less than the maximum tolerable value. Ignoring the delay constraint of the network, the routes are selected as the solution to a linear programming (LP) problem in which the objective is to maximize the minimum lifetime of each node. The solution is implemented in a centralized algorithm, and then approximated by an iterative algorithm based on least cost path routing, in which each step is implemented efficiently in a distributed manner. The second part of the paper incorporates delay guarantee into energy efficient routing by constraining the length of the routing paths from each sensor node to the collection node. Simulations reveal that the lifetime of the network increases significantly by optimal routing, and including delay constraint in energy efficient routing improves the network performance since the delay of the network keeps increasing as the delay constraint is relaxed beyond the value at which the optimal lifetime is achieved. Research supported by National Science Foundation under Grant CMS-0408627 and California Department of Transportation. Sinem Coleri Ergen received the BS degree in electrical and electronics engineering from Bilkent University, Ankara, Turkey, in 2000, and the M.S. and Ph.D. degrees in electrical engineering and computer sciences from University of California Berkeley (UCB), in 2002 and 2005. Since January 2006, she has been a postdoctoral researcher in electrical engineering at UCB. Her research interests are in wireless communications and networking with a current focus on energy efficient system design for sensor networks. She is a member of the Sensor Networks for Traffic Monitoring project at UCB. She received Regents Fellowship from University of California Berkeley in 2000. Pravin Varaiya is Nortel Networks Distinguished Professor in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley. From 1975 to 1992 he was also Professor of Economics at Berkeley. From 1994 to 1997 he was Director of the California PATH program, a multi-university research program dedicated to the solution of Californias transportation problems. His current research is concerned with communication networks, transportation, and hybrid systems. He has taught at MIT and the Federal University of Rio de Janeiro. Varaiya has held a Guggenheim Fellowship and a Miller Research Professorship. He received an Honorary Doctorate from LInstitut National Polytechnique de Toulouse, and the Field Medal of the IEEE Control Systems Society. He is a Fellow of IEEE and a member of the National Academy of Engineering. He is on the editorial board of several journals, including “Discrete Event Dynamical Systems” and “Transportation Research—C”. He has co-authored three books and more than 250 technical papers. The second edition of “High-Performance Communication Networks” (with Jean Walrand) was published by Morgan-Kaufmann in 2000. “Structure and interpretation of signals and systems" (with Edward Lee) was published by Addison-Wesley in 2003. Varaiya is a member of the Board of Directors of Sensys Networks.     

A low-power rail-to-rail input-range linear delay element circuit

Delay elements are one of the key components in many time-domain circuits such as time-based analog-to-digital converters. In this paper, a new rail-to-rail current-starved delay element is proposed which not only presents good linearity for the voltage-delay curve over the input range of ground to supply voltage, but also it consumes a dynamic power only during the transition times without consuming any static power. The proposed delay element is designed and simulated in a 0.13-µm CMOS technology with a supply voltage of 1.2 V. Post-layout simulation results demonstrate that the proposed circuit has a linear voltage-delay transfer function with a voltage-to-time gain of −1.33 ps/mV. Moreover, when samples of a full-scale sin-wave input signal are applied to the proposed circuit with a clock frequency of 100 MHz, the power consumption is 30 µW, and signal-to-noise-and-distortion ratio (SNDR) of the output delay times is 30.4 dB, making it suitable for use in a time-based analog-to-digital converter with up to 5-bit resolution.     

Catia aided radome analysis using geometric optics method

In this paper, the Geometric Optics (GO) method using the approximate ray paths coupled with the Computer Aided Tri-dimensional Interface Application (CATIA) meshing modeling are implemented to analyze the performance of electric large three-dimensional dielectric radome-enclosed antenna of arbitrary contour shape. The surfaces of the radome are approximated by planar triangular patches, the influences of various number of patches on power transmission coefficient and Insertion Phase Delay (IPD) via an ogive and a conical radome are discussed by the hybrid method. The simulation results indicate that computational error from planar triangular patches can limit in one percent, meeting the engineering application requirements.     

典型微区环境下信道特性的仿真结果

多径效应产生的扩散效应一直是无线信道研究的主要问题。作者利用自行开发的无线信道仿真软件对微区环境下的主要信道特性进行了大量的仿真，得到了典型微区环境下的传播损耗，时延扩展和角度扩散等主要信道特性的描述。     

NGN业务的端到端时延分析

对下一代网络（NGN）业务的QoS特性进行了分析，重点针对实时的语音业务进行了端到端的时延分解，给出了可供工程设计参考的时延分配方法。     

控制回路振荡及振荡原因诊断平台设计

控制阀粘滞特性是导致控制回路振荡的一个重要原因,对控制回路振荡原因的诊断对实际工业控制具有重要的意义。本文利用MatlabGui设计了控制回路振荡原因诊断平台,集成了替代数据方法、继电器方法、基于输入输出特性的定性描述法、互相关方法、信号概率密度法五种方法。通过振荡原因诊断平台对基于Kano粘滞模型生成的仿真数据进行了振荡原因诊断,仿真结果初步验证了平台的有效性,当前平台设计、布局、算法优化性等方面仍需要进一步增加、改进。     

OFDM技术在无线接入中的应用

文章首先介绍了OFDM的关键实现技术，然后结合不同无线通信环境的特点，对OFDM在无线局域网和固定无线接入中的应用进行了分析。     

罗兰-C信号快速捕获方法及其性能分析

罗兰-C系统与全球导航定位系统(GNSS)相结合已成为新的应用模式,为用户提供可靠的定位、导航和授时服务。针对传统罗兰-C接收机信号捕获时间长、抗噪性能差等缺点,该文提出一种基于延迟相关技术的罗兰-C信号抗噪快速捕获方法,并从理论分析和仿真实验两个方面验证了该方法的有效性,解决了强噪声背景下罗兰-C信号的快速捕获问题。结果表明：罗兰-C延迟相关捕获方法的捕获时间优于200 ms,抗噪性能优于-10 dB。     

基于电机温度时滞耦合系统的自抗扰控制研究

电机过热时会造成绕组绝缘降低,严重时会烧坏电机。由于电机温度存在较大的时滞性和耦合性,无法用准确的数学控制模型进行描述。传统的双通道PID控制算法降低了对电机温度的控制精度,导致电机过热。提出一种基于自抗扰控制算法（ADRC）的电机温度控制方法,以双通道PID控制方法为基础进行了改进,对内外扰动进行综合处理,对扩张状态观测器进行估计,并在反馈中引入非线性特性。利用Matlab平台模拟实验环境和实际电机,与传统的PID控制算法进行了仿真实验对比。结果表明,自抗扰控制算法能够有效的对电机温度进行解耦控制,实现了对电机温度的精确控制。