FTTH中H.248协议相关问题研究和实践

主要介绍中国联通天津分公司在开展FTTH业务过程中,针对软交换和xPON ONU中语音网关之间应用Megaco/H.248协议发生的非法注册和控制效率低的问题,通过对Megaco/H.248协议的研究采用了诸多创新性的优化手段,使用专业测试软件进行数据采集、理论分析、制定相应解决方案,解决了媒体网关控制器和媒体网关之间非法注册的问题,同时通过调整协议中的定时器和优化了软交换的处理能力,确保天津联通FTTH业务高速发展.     

软交换网络体系结构和SIP协议

网络结构和控制协议是最为重要的组网技术，软交换网络结构的重要特点是其明确的功能分层，其于会话启动协议（SIP）的呼叫控制协议、以H.248为主的边缘接入协议以及SIGTRAN信令互通传送协议构成了软交换网络的控制核心，首先给出软交换网络的分层结构，简要阐述各层功能以及软交换系统的结构，然后深入讨论了软交换网络的核心协议－－SIP和电话应用的协议SIP（SIP－T），并将其与H.323协议和与承载无关的呼叫控制（BICC）协议进行了比较。     

软交换网络简述

随着IP网络时代的到来和人们对通信业务越来越高的要求,传统的公共交换电话网络(PSTN)已显露出其自身的缺点和不足,软交换网络的出现,掀开了电信网业务崭新的一页,实现了语音、数据和视频多媒体业务,是网络融合的趋势。文章通过介绍软交换网络的分层结构、体系结构、SIP/H.248信令协议和业务,阐述了软交换网络的概况和SIP协议的应用,最后通过软交换网络的展望,展示了其强大的发展空间和生命力。     

H．248协议在通信网络中的应用

对下一代通信网络的结构以及网络各个层次进行了细致说明,剖析了软交换控制设备的内部功能模块。H．248协议是软交换网络中主要通信协议。从H．248协议的结构入手,在对其呼叫流程进行说明的基础上,提出了一种修改用户信号音的新思路。此方式与目前电信运营商采用的智能网方式相比,修改更灵活,且无需业务申请和付费,具有一定的市场前景。     

单IP提供10万网关注册在5020MGC软交换中的实现

当前5020MGC软交换单IP地址最多支持20 000个H.248网关,可实现共计72 000个用户的注册和呼叫。随着FTTH、PON等接入设备的大量部署,电信运营商从网络运维的需求和网关小型化的实际出发,需要核心网软交换能提供IP收敛的功能。重点介绍了5020MG软交换中全新设计的CoCoProxy软件模块及其实现方式,通过该功能可以有效提升网关注册容量,使得单IP地址支持100 000个H.248网关注册及呼叫。     

单IP提供10万网关注册在5020MGC软交换中的实现

当前5020MGC(5020媒体网关控制器)软交换单IP地址最多支持20000个H.248网关,可实现共计72 000个用户的注册和呼叫。随着FTTH(光纤到户)、PON(无源光纤网络)等接入设备的大量部署,电信运营商从网络运维的需求和网关小型化的实际出发,需要核心网软交换能提供IP收敛的功能。文章重点介绍了5020MGC软交换中全新设计的CoCoProxy软件模块及其实现方式,通过该功能可以有效提升网关注册容量,使得单IP地址支持100 000个H.248网关注册及呼叫。     

软交换体系中H.323和SIP协议的互通

软交换技术是下一代网络(NGN)的核心技术,它可以成为下一代分组网络中为语音业务、数据业务和视频业务提供呼叫、控制和业务的核心,同时也是电路交换网向分组网演进的关键：H．323、SIP、MGCP等信令系统之间的互通．是我们实现软交换核心设备的基础：本文简要介绍了软交换技术,讨论了软交换体系中H．323与SIP信令协议．并研究两者之间的互通问题。     

PC2Phone业务中的安全注册问题探讨

本文所指的PC2Phone业务是由基础电信运营商经营的，基于宽带互联网的软电话终端或硬电话终端发起，呼叫至电路交换网电话的语音业务。由于这种业务的发起方来自互联网，我们不能象传统电话网那样根据用户线判断用户身份，所以我们需要采取一种新的方法验证用户的真实身份。这样就需要在呼叫控制信令中进行用户的注册，但是在互联网上，数据传递的过程中存在比较高的被窃取的风险，因此在注册的过程中需要采用加密的手段来确保合法用户的身份即能够得到有效的验证，同时在验证过程中其身份不会由于被非法的用户截获而进行仿冒。可以说，解决好用户注册的问题是PC2Phone业务有序开展的一个重要前提。而要解决用户安全注册的问题，我们先要从密码学的基本原理谈起。     

FTTx中BAC设备组网方案研究

在接入网络"光进铜退"迅速推进的形势下,越来越多贴近用户的语音接入设备连人软交换网络.如何保证软交换网络的安全与服务质量是电信运营商关注的一大问题.本文介绍了软交换边缘接入控制(BAC)设备的定义、作用与网络中所处位置,根据现网中语音接入设备所处的不同场景提出了BAC设备的部署策略,并对未来应用的大容量BAC设备的组网方案进行了研究.     

VoIP体系协议的分析与研究

VoIP是一种在Internet网络上进行语音通信的新业务。H.323、MGCP、Skype、H.248、SIP是VoIP的重要协议。论文在分析这些协议结构的基础上,研究和对比了各种VoIP协议的使用特点,为架构不同的VoIP网络提出了协议选择建议。     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

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.     

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.     

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.     

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.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.