Current-crowding effect in diagonal MOSFET's

Electrical and reliability characteristics of diagonally shaped n-channel MOSFETs have been extensively investigated. Compared with the conventional device structure, diagonal MOSFETs show longer device lifetime under peak I_sub condition (V_g =0.5 V_d). However, in the high-gate-bias region (V_g=V_d), diagonal MOSFETs exhibit a significantly higher degradation rate. From the I_sub versus gate voltage characteristics, this larger degradation rate under high gate bias is concluded to be due mainly to the current-crowding effect at the drain corner. For a cell-transistor operating condition (V_g>V_d), this current-crowding effect in the diagonal transistor can be a serious reliability concern     

多天线对角空频编码传输

将平坦衰落信道的对角代数空时码(DAST)推广到频率选择性衰落信道,提出了对角空频分组码(DSF).基于多输入多输出天线和正交频分复用(OFDM),DSF码将满秩的旋转信号星座和子载波分组结合起来,以对角发送方式(每时刻只有一个天线发射)发射旋转信息符号向量的每个分量.成对错误概率分析表明:在频率选择性信道中,通过选择最佳的旋转矩阵,这种DSF-OFDM系统能实现满分集增益和最大的编码增益.系统采用了球型解码器对DSF码实施最大似然解码,它的解码复杂性是中等的,并且,解码算法的复杂性与信号星座的维数无关.此外,和先前所提出的一些方法相比,提出的空频码还具有频谱效率高(1symbol/s/Hz)的性能特点.     

High-gain step-profiled integrated diagonal horn-antennas

Dipole-excited integrated horn antennas are limited by their large flare angle of 70°, which is inherent in the anisotropic etching process of 〈100〉 silicon wafers. The large flare angles does not allow for integrated horns with gain higher than 13 dB and for 10-dB beamwidths less than 90°. A step-profiled horn is proposed which reduces the effective flare angle of the horn and allows gains in the region 17 dB to 20 dB to be achieved. The symmetry of the horn's radiation pattern is enhanced by positioning the exciting dipole along the diagonal of the horn cavity. A specific design example is shown with a gain of 18.4 dB and a 10-dB beamwidth of 37° in the E, H and 45° planes. The coupling efficiency of this horn to a Gaussian beam is calculated to be 83%. An equivalent smooth envelope-horn was built at 12.1 GHz and the measured patterns agree well with theory. The integrated step-profiled horn is well suited for millimeter-wave and terahertz focal plane imaging arrays requiring a large number of elements     

ASON动态路由解决方案浅析

以自动交换光网络(ASON)标准路由模型为基础,介绍了域间路由协议在ASON路由中的实现方法,并针对其动态路由算法的不足进行分析,结合ASON控制平面发展趋势提出了初步的解决方法.     

路由协议测试研究—边界网关路由协议BGP—4测试

现有测试理论和方法在路由协议测试中面临挑战。由于路由协议具有与通信协议不同的特点,现有测试系统的能力已经难以满足测试需求,本文介绍了在路由协议测试中进行的探讨和实践,深入分析了路由协议的特点,在此基础上对现有测试方法的适用性进行考察,选择了相应的测试方法和结构,扩充了测试系统中的考实现增强测试能力,设计了TTCN格式的测试集,通过测试实践,证实所用方法手段的有效性,并为国产路由器的开发提供了有力的支持。     

GMPLS路由算法研究

首先简要介绍了路由算法的一些特征及设计目标.在此基础上重点讨论了基于GMPLS的网络各种不同的路由算法,并对各种路由算法做了简单的对比.     

零陷展宽对角载入算法

提出了零陷展宽对角载入算法,该算法既解决了干扰在快速运动时,干扰零陷过窄的问题,又解决了协方差矩阵误差和导向矢量误差存在时,算法稳定性变差的问题。同时,通过对角载入因子和采样协方差矩阵间的关系确定了对角载入算法载入因子的值。计算机仿真结果表明该算法有很好的稳健性,以及较宽的零陷。     

Double-sided least-squares problem with diagonal constraints

The double-sided least-squares problem with a constrained parameter matrix is formulated and solved using multilinear products.     

On diagonal algebraic space-time block codes

Theoretical and practical aspects of diagonal algebraic space-time block codes over n transmit and m receive antennae are examined. These codes are obtained by sending a rotated version of the information symbols over the principal diagonal of the n /spl times/ n space-time matrix over n transmit antennae and n symbol periods. The output signal-to-noise ratios of two predecoding filters and two decoding algorithms are derived. Analysis of the information loss incurred by using the codes considered is used to clarify their structures, and the expected performances. Different algebraic real and complex rotations presented in the literature are analyzed and compared as regards the achieved coding gains, the complexities, performances, and peak-to-mean envelope power ratios.     

Two-dimensional block diagonal LMS adaptive filtering

The paper is concerned with the development of two-dimensional (2D) adaptive filters using the block diagonal least mean squared (BDLMS) method. In this adaptive filtering scheme, the image is scanned and processed block by block in a diagonal fashion, and the filter weights are adjusted once per block rather than once per pixel. The diagonal scanning is adopted to avoid the problems inherent in the 1D standard scanning schemes and to account for the correlations in two directions. The weight updating equation for 2D BDLMS is derived, and the convergence properties of the algorithms are investigated. Simulation results that indicate the effectiveness of the 2D BDLMS when used for image enhancement, estimation, and detection applications are presented     

一种基于自适应对角加载的雷达通道均衡算法

雷达通道均衡可以保证通道间的幅度和相位一致性。对角线加载技术能减弱均衡器阶数增加带来的矩阵病态的影响,改善了均衡性能,但是加载量的确定是一个比较困难的问题。文中提出采用自适应对角线加载进行雷达通道均衡的算法,提高了通道均衡的稳健性。仿真结果证明了该算法的有效性。     

Active routing

Active routing permits individual customers, network managers, or network owners to control the paths that their data takes through the network. The objective is to allow routing mechanisms that provide quality of service (QoS), mobility, etc., to be quickly deployed, without waiting for standards, and to allow different routing mechanisms, that provide similar services, to compete. The current work on label switching (MPLS) can also be used to give high level customers, such as virtual private networks (VPNs), more control over their paths. We show how active routing can extend the capabilities of MPLS. We address several implementation issues, including pricing and distributed sandboxes. Pricing or policing must be used to limit the resources that customers acquire, in order to encourage them to use network resources economically. Sandboxes must be used to limit the resources that the participants acquire, in order to limit the harm that they can inflict on other participants. Active routing creates a free market system where network providers compete to sell their resources and implementers compete to sell their active routing programs. We establish a framework to quantitatively compare networks and service providers. As an example, we route Internet protocol (IP) telephony over combinations of circuit and packet networks     

Minimum-interference routing based on flow maximisation

A new on-line routing algorithm based on the notion of minimum-interference is presented. The algorithm maximises the sum of residual flows of ingress-egress pairs, using a simple heuristic method. It achieves good results in terms of total bandwidth routed     

BGP路由的动态性研究

BGP路由的不断变化使得对协议策略的维护、定位路由故障、控制协议流量十分困难。本文从优化BGP路由策略配置、解释产生路由更新的根本来源、预测BGP的路由行为等角度对BGP路由的动态特征的相关研究进行介绍,进而对不同研究进行比较分类,剖析其优劣。     

Introducing intelligent sensors in presses for plastic material injection

This paper presents some theoretical and experimental results concerning the introduction of advanced sensors in the design and development of a new generation of presses for plastic material injection used to produce washing machine tubs. The architecture of the control system for the presses is based on a distributed solution and relies on fieldbus communications to obtain a graceful migration path to the adoption of sensors of a new generation. This enables a dramatic decrease in both the cabling complexity and cost, together with a significant improvement in the performance of the whole machine. The adoption of the field network to connect sensors and actuators to the controller has been carefully evaluated by means of a preliminary theoretical analysis. Then, two test systems have been implemented to collect data and performance figures by carrying out experiments and measures on some of the real devices selected for the design of press control equipment.     

Optimal diagonal precoder for multiantenna communication systems

In this paper, we examine a multiantenna single-user wireless communication system fitted with a QR-based successive cancellation receiver (QR receiver). Initially, our consideration is confined to uncoded binary phase shift keying (BPSK) signals transmitted through independent and identically distributed (IID) Rayleigh fading channels and to the design of an optimum precoder for the transmitter. For minimum feeding back of the channel state information (CSI) to the transmitter from the receiver, we stipulate the precoder to be in the form of a power loading square diagonal matrix. We proceed to develop the theory for the design of this diagonal matrix based on the minimization of the lower bound of the average bit error rate (BER) of transmission. The design obtained provides substantially lower error rates than most of other existing schemes under the same environment. The corresponding gain in signal-to-noise ratio (SNR) can be several decibels. To further improve the performance, we extend the design to include an optimal detection order of the received bits using an iterative approach. This iterative process proves to have fast convergence and results in a design providing significant SNR gain. We also propose a subchannel dropping scheme for cases in which SNR is low, and when the minimum BER precoder is equipped with this scheme, its average performance can be substantially superior to the Vertical Bell Laboratories Layered Space-Time (V-BLAST) detection. We extend our design of the optimum precoder to quadrature amplitude modulation (QAM) modulation scheme and similar performance gain has been observed.     

DTN routing using explicit and probabilistic routing table states

Routing in communication networks involves the indirection from a persistent name (ID) to a locator. The locator specifies how packets are delivered to a destination with a particular ID. Such a mapping is provided by a routing table entry, i.e. state. In a DTN, it is hard to maintain routing state because intermittent connectivity prevents protocols from refreshing states when they become inaccurate. In prior work, per-destination state mostly corresponds to utilities, where a high utility value about a destination implies that the probability to encounter the destination for the node maintaining the state is high. This approach depends on a particular mobility pattern in which nodes that met frequently in the past are likely to encounter in the future. In this paper, we use the concept of weak state that does not rely on external messages to remain valid (Acer et al. in MobiCom ’07: proceedings of the 13th annual ACM international conference on mobile computing and networking, pp 290–301, 2007). Our weak state realization provides probabilistic yet explicit information about where the destination is located. We build Weak State Routing protocol for Delay Tolerant Networks (WSR-D) that exploits the direction of node mobility in forwarding. It provides an osmosis mechanism to disseminate the state information to the network. With osmosis, a node has consistent information about a portion of the nodes that are located in regions relevant to its direction of mobility. Through simulations, we show that WSR-D achieves a higher delivery ratio with smaller average delay, and reduces the number of message transfers in comparison to Spray & Wait (Spyropoulos et al. in Proceedings of ACM SIGCOMM 2005 workshops: conference on computer communications, pp 252–259, 2005) and Spray & Focus (Spyropoulos et al. in IEEE/ACM Trans Netw, 16(1):77–90, 2008), a stateless and a utility based protocol, respectively.     

基于主动网络的多约束路由探测算法

本文提出了一种基于主动网络的多约束路由探测算法MAR(Multi-constrained Active Routing).与传统路由算法相比,MAR不仅能灵活地提供多种约束条件的服务质量保证,而且充分发挥了主动网络的可编程和自定制能力,允许用户根据业务要求和网络状况自定制约束条件和相关参数.通过仿真MAR算法在各种网络条件下的性能表明,MAR算法能够提高多约束条件寻路的成功率.     

IPSEC/VPN动态路由问题研究

图1 网络拓扑结构图引 言IPSEC目前是构建3层安全VPN的关键技术,它通过安全策略在IP层提供安全服务,其中虚拟网络拓扑结构的变化是影响安全策略的主要因素之一。拓扑结构变化主要有两种:安全网关之间拓扑关系的改变;安全网关所保护子网的改变。为了适应这些变化,必须对安全策略做出相应的调整,通过手动方式分发策略扩充性、安全性都较差,通过策略管理系统来分发策略是很好的解决方案,但目前还没有成熟、统一的策略管理协议,并且在网络结构很复杂的情况下,策略管理的工作量也比较大。因此IETF VPN相关工作组根据VPN的需求,提出通过…