光纤通信系统技术的发展与展望

本文对光纤通信系统的若干热点技术领域的发展趋势作了简要总结和展望。主要结论是: SDH将向融合的低成本多业务平台转型;某些新型光以太网解决方案正逐渐具备公用电信网所要求的必备功能和性能,成为城域多业务网的可选技术,但还需要解决一系列问题;40Gibt/s系统技术已趋成熟,但是大规模应用还需时日;超长距离WDM传输系统技术和市场均已成熟;粗波分系统在我国城域网具有良好的发展前景;点到点WDM传输将走向自动交换光网络;EPON和GPON将成为主导FTTH技术,但大规模应用还需要解决成本、配套技术和应用问题。     

光通信技术的发展趋势和展望

本对光通信技术的若干热点领域的发展趋势做了简要评述和展望。主要结论是SDH将向下一代融合的多业务平台转型：40Gbit/s系统的发展将继续推迟并可能首先在短距离互联上获得应用：波分复用除了继续向超长距离和超大容量发展外,粗波分系统将在城域网获得应用;点到点光通信将向光联网方向演进：光以太网将成为城域多业务网的可选技术,但还需要解决一系列问题：无源光接人网技术有突破,但大规模应用还需要解决成本和配套问题;为满足光通信技术的发展需要．下一代光纤的应用时机已经成熟。     

承载IPTV业务的IP城域网的优化和改造

随着宽带用户和宽带应用的快速发展,目前以承载互联网接入业务为主的IP城域网难以适应新业务发展的要求,尤其是以IPTV为代表的新的宽带业务的应用,对lP城域网提出了巨大的挑战:同时,随着通信技术的不断发展,运营商必须作手考虑对IP城域网进行优化改造,使之能够适应IPTV等应用的要求.本文通过分析IPTV的系统架构,IPTV的技术特点、IPTV对城域网的关键性技术要求、IP城域网的技术发展出发,将IP城域网分为城域骨干网和宽带接入网进行分析,指出城域网在核心网络结构、带宽、QoS、可靠性,安全性和组播技术的运用等方面存在的不足,论述了将核心网络由三星型改造成双星型、核心层的设备扩容和接入网的优化等方面的内容,并充分布署组播技术,建设一个高品质的、支持多业务的IP承载网,使之不仅能够依然满足互联网应用的需要,而且能够充分保障IPTV业务的要求.该项目建成后,在网络容量、网络结构、业务控制点的能力都有了巨大的提高,对IPTV业务的推广和企业发展起到非常大的作用.由于是在城域网范围内首次大规模引入组播技术,是新技术在城域网范围内的突破.     

PTN市场巨大烽火通信充分应对

经过两年多的测试和试验,分组传送网(PTN)技术已逐渐成熟,成为了城域网的主流技术,2010年将进入大规模部署和实际应用阶段.在PTN的规模部署期,将会面临许多新的问题和新的挑战.     

软交换AG承载方案的探讨

针对目前软交换的大规模建设及应用,AG不断的引入和建设,如何实现AG上连的业务承载是承载网领域迫切需要研究的课题。文章分析了NGN的体系结构和承载方案,深入阐述了城域网VPN、城域网SR延伸和MSTP传输网三种AG上连承载方案,提出了选择具体技术方案的建议。     

CWDM技术在通信网络中的应用分析

文中首先对CWDM技术进行了介绍,包括CWDM的系统组成和系统原理等,然后以城域网为例分析了CWDM技术在通信网络中的应用,并总结了CWDM技术在通信网络中的优势,最后提出了一些可行的应用维护意见。综上所述,目前CWDM在城域网、接入网、企业网、校园网等领域具有广泛的应用前景。     

WiMAX无线城域网的应用研究

在WiMAX技术和IEEE 802.16标准的基础上,研究了WiMAX无线城域网的应用;给出WiMAX无线城域网的应用领域以及具体应用设想.研究结果表明,WiMAX无线城域网的应用前景广阔.     

高带宽视频大规模组网的组播技术实用性探究

某单位以专属城域网为基础,从实用性出发,综合应用组播技术和视频技术,并结合特定的组播辅助软件,完美实现了大规模高带宽实时视频应用需求。经过多年实际使用验证,该系统具备高可用性、高可靠性和灵活扩展能力,充分利用了网络资源。本文对于如何组建专属网络的大规模多点高带宽应用,具有相当地适应。陛和借鉴意义。     

城域网为光通信提供了又一竞争机会

当今的通信世界已把 SDH和 DWDM技术作为传输系统的主要技术 ,尤其是随着因特网应用的迅速发展 ,DWDM技术以强劲的势头进入其他领域 ,显示出了喜人的市场前景。北电、华为、UT斯达康等公司根据自身的技术特点 ,分别推出了技术方案和城域网产品。北电网络作为光通信领域有实力的供应商 ,在世界光网络市场占有最大份额 ,他们非常看好城域网市场 ,尤其注意光以太网的市场机遇和前景。他们认为 ,光传输具有目前所有传输技术所不可比拟的优势。城域网的发展将充分利用光纤技术大容量、长距离的传输优势。他们与康宁公司合作推出了针对城域…     

IP城域网引入虚拟交换机技术的研究

首先重点介绍虚拟交换机及部署方式,多虚一技术和一虚多技术两种虚拟技术在网络中的应用,然后论述虚拟交换机在现网中的实验和数据统计分析,最后给出虚拟交换机在城域网中的部署方案建议,虚拟交换技术的引入不仅能够大幅降低故障率,减轻运维压力,提高链路和端口的利用率,降低总体投资成本,而且还能够为后期城域网的大规模提速打下坚实的网络基础。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks