IP电话网络连续处理技术

在IP电话系统中,鉴权处理、接续过程、用户和计费管理、网络管理都与传统电话技术有所不同。本文简要介绍电话到电话方式的IP电话所涉及到的用户验证、路由选择、呼叫处理、计费和网管等技术。一、IP电话网络组成及呼叫处理过程如图1所示,IP电话网络主要由同关（Gateway）、关守（Gatekeeper）、用户管理和计费系统（Billingsystem）和网管系统等组成。网关是传统PSTN电话网和Internet网间的桥梁,完成语音的压缩、IP打包及与PSTN网的信令配合等工作。关守单独或与计费系统协作完成对用户的身份进行验证,完成地址转换、路由选择…     

基于数据库的IP网络管理研究

针对广泛应用的网络管理协议SNMP,研究了如何高效地进行基于SNMP的IP网络管理。首先分析了目前基于SNMP的IP网络管理框架结构中存在的一些问题,然后有针对性地提出了基于数据库的SNMP网络管理结构,并具体分析了改进结构的工作机制。     

IP RAN的IP网络架构选择

移动接入网（RAN）IP化的最大的问题将是使IP地址资源严重匮乏的状况即时恶化,选择合理的IP网络架构,采用实用、有效的IP网络技术方案对移动接入网IP化的成败和发展进程至关重要。     

面向业务和网络协同的未来IP网络架构演进

IP技术作为互联网的技术基础,在今后5～10年如何发展是通信行业面临的关键问题。分析了传统IP网络架构的成功与不足,提出未来IP网络既要继承传统IP技术的设计原则,比如端到端原则和分层解耦原则,又要解决现有IP网络中业务和网络过于割裂的问题。从网络演进和未来业务需求的角度出发,认为未来IP网络的核心问题是要加强业务和网络的协同,提出了改进后的IP网络设计原则“横向：服务化网络赋能的端到端架构,纵向：智能控制面支撑的分层模型”,并且基于此原则提出了未来网络的参考架构。     

IP核网络管理系统的设计及实现

目前,基于IP核复用的SOC技术已经发展成为IC设计的一种主流技术,而SOC设计的关键是可复用IP核的获取.IP核网络管理系统可以有效的组织和管理IP核数据,并且为用户查找、选择合适的IP核提供一个便利的公共平台.文章主要分析了IP核数据的特点,从而确立了IP核的数据结构;并且详细讨论了IP核网络管理系统的设计考虑与实现过程.     

基于TCP协议的网络管理系统的设计与实现

目前,网络管理技术主要有两种：基于TCP/IP网络的简单网络管理协议SNMP和由ISO开发的公共管理信息协议CMIP。SNMP使用了提供无连接服务的传输层协议（UDP）。其特点是不保证数据接收的顺序性、完整性和可靠性,不适于较复杂的电信网络的管理。CMIP协议使用的是面向连接的方式,但是需要OSI七层协议栈的支持,实现起来较复杂,因此尚未得到广泛使用。虽然Internet的有关组织提出了公共管理信息服务与协议（CMOT）,以在TCP/IP协议上实现CMIS服务,但这是一种过渡解决方案,许多网络管理系统开发商并不想花费时间实现一个…     

基于移动代理的IP网络管理及其安全机制

相对于传统的网络管理方法，基于移动代理技术的网络管理把智能部分移到原始数据产生的地方，具有灵活、分布、可扩展和容错性好等优点，克服了传统的集中式网络管理的毛病。结合IP网络大量存在SNMP代理的现状，提出了一种基于移动代理的网络管理系统，分析了可能遇到的安全威胁并研究了解决方法。     

IP QoS研究的现状与发展趋势

目前，随着电信业务的引入，IP网的服务质量（IP QoS）成为下一代Internet的重要研究课题。由于IP协议的无连接特性和IP网络松散的控制管理方式，使这项研究面临很大的挑战。IPQoS的研究范围十分广泛，不仅包含路由和业务流量控制，还涉及到网络管理、计费和网络测量。当前主要的IP QoS技术集成服务（IntServ）集成服务的基本思想是在传送数据之前，根据业务的QoS需求进行网络资源预留，从而为该数据流提供端到端的QoS保证。资源预留协议（RSVP）是集成服务的核心。这是一种信令协议，用来通知网络节点预留资源。如果资源预留失…     

在VC++6.O平台下基于SNMP网络管理软件的开发

SNMP（简单网络管理协议）是目前TCP/IP网络中应用最为广泛的网络管理协议.本文详细介绍了SNMP的基本原理和框架结构,并给出了一个在VC＋＋6.0平台下利用SNMP＋＋进行快速网络管理应用程序开发的简单例子.     

从传统移动通信网向全IP网络的演进

目前在国际上,各国都在积极研究“全IP网络”技术。简单地说,就是未来移动通信网是建立在IP技术的基础上,其中包括无线接入网和移动核心网都采用IP技术。整个移动通信网都将IP化,所以叫做全IP网络。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.