浅析SIP-I协议

一、引言 下一代网络(NGN)是以IP为基础,以软交换为核心的技术。软交换中的核心控制协议是SIP协议,由IETF发起和制定,并且被3GPP,ITU-T以及众多电信设备运营商,IT厂商采用,作为下一代网络多媒体业务领域的核心协议。     

基于IP的移动软交换核心网组网策略

随着软交换技术的日益成熟和3G牌照发放的推迟，基于IP的移动软交换方案被认为是运营商提升核心竞争力的重要技术手段之一，并成为移动运营商扩容和优化2G核心网选择。文章对2G核心网络中的移动软交换技术进行了详细的介绍，并给出了基于IP方式下的组网方案。     

以软交换为核心的下一代网络综述

首先阐述了以软交换为核心的下一代网络(NGN)的系统架构和涉及的相关协议；接着描述了NGN的系统特点；最后论述了待解决的四个问题，包括NGN继承了IP网所具有的缺陷，网络的安全性和可管理性需要解决，各种协议亟待标准化，新兴的能够吸引运营商的业务还很少。目前软交换技术也仅仅处于摸索阶段，要实现利用软交换来接入各种终端设备、接入各种网络还需要漫长的道路。     

基于IP的移动软交换核心网组网策略

软交换技术是向下一代网络演进的核心技术。在移动核心网中引入软交换技术，可以实现核心网内资源的共享和集中控制。从而提高整个网络的利用率、降低运营成本。当前软交换技术已经成熟，提供业务的能力也得到了验证，因此目前在移动运营商的2G核心网络中都大量使用移动软交换设备，目前的应用模式多为软交换设备、分离架构、TDM承载语音的软交换组网方式。随着IP骨干网的建设初具规模。为了最大限度地提升骨干传输网的利用率和网络投资的效益，进一步发挥软交换技术的优势，在现有条件下的GSM核心网络中实现VoIP（语言IP化）和信令IP化、宽窄带信令互通是目前2G移动核心网的发展方向。本文将主要讨论基于IP的移动软交换在2G网络中的应用方案。[编者按]     

移动核心网语音IP化以适应未来3G、IMS格局的几点分析

目前移动核心网规划、建设以软交换技术为核心，将业务与信令控制分开，基于IP承载的面向3G、IMS的软交换核心网，实现既支持2G网络，又能适应未来3G网络的思路已为业界所公认。在移动核心网软交换化以适应未来3G、IMS格局进程中，语音IP化即IP承载网承载语音是非常重要的一环。本文以陕西移动为例就移动核心网软交换化进程中语音IP化阶段的特点，作几点分析。     

电信业务基础设施：业务驱动的多媒体软交换平台

IP技术、软交换技术和电信业务体系结构的进步，极大地推动了电信业的发展。特别是应用使能的IP多媒体域软交换应用，已经展示了软交换巨大的业务潜力。但是，这些软交换技术都是以面向特定应用的产品形式出现的。从电信运营商业务开发的生命周期来看，需要一个动态的、不断发展的业务驱动的软交换平台来支持业务的定义、协议的选择、接入／互联的控制、业务控制、应用控制和网络控制以及对业务和网络能力进行管理。本介绍了UT斯达康公司对软交换在下一代网络中作用的理解，通过可对申信市场的演变和软交换发展历史的分     

以软交换为核心的下一代网络综述

首先阐述了以软交换为核心的下一代网络(NGN)的系统架构和涉及的相关协议;接着描述了NGN的系统特点;最后论述了待解决的四个问题,包括NGN继承了IP网所具有的缺陷,网络的安全性和可管理性需要解决,各种协议亟待标准化,新兴的能够吸引运营商的业务还很少。目前软交换技术也仅仅处于摸索阶段,要实现利用软交换来接入各种终端设备、接入各种网络还需要漫长的道路。     

NGN中的SIP技术

NGN是一个基于IP的全新通信网络,融合了语音、数据、多媒体等多种业务.NGN以软交换为核心,SIP作为软交换的呼叫控制信令协议,简单、开放、灵活,可扩展,已成为NGN的重要技术.本文主要分析了SIP网络结构、SIP消息内容、SDP协议以及SIP在NGN中的应用.     

以软交换为核心的下一代网络综述

首先阐述了以软交换为核心的下一代网络(NCN)的系统架构和涉及的相关协议;接着描述了NGN的系统特点;最后论述了待解决的四个问题,包括NGN继承了IP网所具有的缺陷,网络的安全性和可管理性需要解决,各种协议亟待标准化,新兴的能够吸引运营商的业务还很少.目前软交换技术也仅仅处于摸索阶段,要实现利用软交换来接入各种终端设备、接入各种网络还需要漫长的道路.     

SIP及其在NGN业务集成中的应用

会话发起协议(SIP)是IP网络应用层的控制协议,用于建立、修改和终止两个或多个参与者之间的会话.SIP的设计方法和结构特点使得它成为下一代网络软交换体系的重要技术.3GPP也决定在基于IP的核心网络中采用SIP协议栈实现多媒体会话控制信令.文章介绍了SIP的基本概念并着重阐述和分析了SIP的本质特性及SIP的适用场景,在此基础上,分析了SIP在下一代网络多媒体业务集成中的核心地位和要解决的关键问题并提出了一个SIP和相关技术结合的开放业务集成框架.     

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.     

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.     

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.     

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.     

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.