移动通信准同步码分多址的研究

在简要分析和对比目前各种ＣＤＭＡ标准的基础上,提出了在移动通信反向信道中采用准同步ＣＤＭＡ方式,并在ＣＤＭＡ经典文献「７」的基础上,推导得到了准同步ＣＤＭＡ性能描述公式,可作为经典文献「７」的扩展,准同步ＣＤＭＡ将导致与现有ＣＤＭＡ方式不同的技术设计,初步探讨了ＰＮ码设计,得到了有 结论,下一有待于对准同步ＣＤＭＡ技术包括扩频码设计进行更深入研究。     

第三代移动通信系统（下）

４３种主要的ＩＭＴ－２０００无线传输技术（ＲＴＴ）提案的比较目前国际上呼声最高的３种ＩＭＴ－２０００ＲＴＴ提案是Ｗ－ＣＤＭＡ、Ｗ－ＣＤＭＡＯｎｅ、ＴＤＭＡ／ＣＤＭＡ（ＴＤ－ＣＤＭＡ）,下面对其技术特点和主要技术参数作一比较。４１技术特点Ｗ－ＣＤＭＡ...     

光码分多址技术在光接入网中的应用

无源光网络是光接入网的主要发展方向,ＦＴＴＨ是ＰＯＮ的最终方式,将ＯＣＤＭＡ,ＷＤＭ等技术用于光接入网中,是帝现接入网宽带化的途径之一。介绍了ＯＣＤＭＡ的技术报目前光接入网中多址技术的弊端,探讨了ＯＣＭＤＡ用于光接入网的可能性和优势,提出实现无源光网络多址接入的ＷＤＭ／ＣＤＭＡ方案。     

将CIMS技术引入到SMT生产线中来

ＳＭＴ生产线中的大多数加工设备均为数控设备。它们编程所需的大多数特征数据均可从ＣＡＤ设计系统中得到。如何在ＣＡＤ设计系统和ＳＭＴ自动化加工设备之间建立有机的信息联系和共享，正是ＣＩＭＳ技术所要解决的问题。因此，本文以ＣＩＭＳ系统中的ＣＡＤ／ＣＡＭ为重点，介绍了构造和设计一个电子ＣＡＤ／ＣＡＭ集成系统的方法和思路，以期以引导卢更多的同行加入到该的研究中来。     

PCB—CAD／CAM过程中工艺设计初探

本文阐述了ＰＣＢ－ＣＡＣ／ＣＡＭ过程中有关工艺设计的问题和若干相关数据。其内容具体地反映了目前ＰＣＢ制造技术的水平，以便于电子产品开发人员在ＰＣＢ－ＣＡＤ／ＣＡＭ过程中参考。     

产品聚焦

目前ＩＳ－９５ＣＤＭＡ技术的主要发展方向是ＣＫＭＡ ２０００技术、与ＩＳ－９５ＣＤＭＡ技术相比。为了适应数据业务的需求,ＩＳ－９５ＣＤＭＡ基站需要在信道结构上做相应的改进。这也是ＩＳ－９５ＣＤＭＡ基站的发展方向,目前国内的ＣＤＭＡ基站生产厂商主要是中兴通讯,国外的则主要有摩托罗拉、朗讯、北电网络、爱立信、三星等公司。     

韩国如何把CDMA做成主流

ＣＤＭＡ是于２０世纪６０年代由美国开发出的移动通信技术,最初主要用于军事目的。尽管从技术角度看,ＣＤＭＡ有着优于ＧＳＭ的诸多优势,但从市场占有率角度看,ＣＤＭＡ却处于劣势,其中的重要原因之一就是由欧洲本土开发的ＧＳＭ标准在欧洲这一全球最大的移动通信市场占据着绝对优势。目前,韩国是全球最大的ＣＤＭＡ市场,拥有２７００万ＣＤＭＡ用户。了解韩国ＣＤＭＡ的发展历程,对我国的ＣＤＭＡ产业界也会有不小的帮助。 ＣＤＭＡ的技术优势 与其他两种２Ｇ数字移动通信标准相比,ＣＤＭＡ在技术上有着诸多优势。 首先,ＣＤＭ…     

CDMA技术在光纤通信中的应用研究

近年来，由于码分多址（ＣＤＭＡ）技术在卫星通信和移动通信中的广泛应用，使其越来越受到人们的重视。国外已有不少人正致力将ＣＤＭＡ技术与光纤通信技术相结合，并由此形成了一种新的通信方式－－光纤ＣＤＭＡ通信。目前国内尚无此方面研究成果的报道。本文次对ＣＤＭＡ技术在光纤通信中的一些可能的应用进行了一个初步的研究。并对光纤ＣＤＭＡ系统结构提出了自己的见解。     

联通CDMA的两大法宝——机卡分离和双模手机

联通的第一法宝──机卡分离 众所周知,ＣＤＭＡ技术是不同于ＧＳＭ的北美技术制式,当初在设计ＣＤＭＡ手机时,由于种种原因,并没有采用类似于ＧＳＭ那样的机卡分离技术,而是采用了机卡一体技术。也就是说,ＣＤＭＡ手机没有ＳＩＭ卡,机身上也没有ＳＩＭ卡插槽,网络号码和用户资料是通过特定程序写在手机上的。这种机卡一体技术的弊端在ＣＤＭＡ发展初期并没有充分暴露出来。 机卡一体的诸多不便 但随着ＣＤＭＡ技术的不断完善和发展,随着用户、运营商和制造商数量的不断增加,ＣＤＭＡ的这种机卡不分离无论是给运营商还是用户都带…     

与CDMA国际漫游相关的几个问题

目前,越来越多的国家采用了基于ＩＳ９５的ＣＤＭＡ系统,用户不断增加,我国也开始着手建设ＣＤＭＡ网络。在这种国际国内大背景下,ＣＤＭＡ用户国际漫游问题逐渐成为ＣＤＭＡ领域的一个热点问题。有些人认为,ＣＤＭＡ系统实施国际漫游很困难,这是ＣＤＭＡ系统的一个缺陷。事实上,这种情况是由于ＣＤＭＡ技术管理方式造成的。因为与ＧＳＭ系统相比较,ＣＤＭＡ相关技术的管理方式工作程序与我国传统的管理方式工作程序有很大的差别,使人产生误解。本人将在工作中遇到的相关问题简要总结如下,希望能对读者了解情况有所帮助。１ＣＤＭ…     

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.