共查询到20条相似文献,搜索用时 46 毫秒
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VoLTE需要终端、无线和核心网的全面支持和优化,目前来看实现复杂度较大。CSFB是在产业界未实现VoLTE时提出的一种相对较为简单的语音解决方案。由于目前VoIP业务的性能指标未能达到现有电路域语音业务的质量,而且需要全网布署IMS,因此在现有网络基础上,形成了三种不同的LTE语音解决方案:基于双待机终端方案、CSFB和VoLTE。CSFB和VoLTE均为3GPP定义的LTE语音解决方案,两个方案在3GPP规范中均有明确定义。VoLTE需要终端、无线和核心网的全面支持和优化,从目前来看实现复杂度较大。CSFB是在产业界未实现VoLTE时提出的一种相对较为简单的语音解决方案。 相似文献
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承载于LTE的语音业务(VoLTE)无线频谱利用效率优于传统CS语音,高清语音和视频编解码的引入显著提高了通信质量,VoLTE呼叫接续时长较传统CS语音大幅缩短.主要针对VoLTE的接续时延,提出基于信令消息的VoLTE接续时延优化,依据VoLTE终端在接续过程中不同阶段的网元间交互的信令消息,从寻呼、域选、资源预留3个阶段分别对影响VoLTE接续时延的因素进行针对性分析,并给出相应的解决方案. 相似文献
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文章对LTE网络下的目标语音解方案-VoLTE技术做了详细的分析,涉及VoLTE技术实现的各个层面,包括VoLTE技术的基本架构、基本业务流程、设备功能要求和互通技术等,并对几种LTE语音解决方案的应用进行了比较和总结。 相似文献
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VoLTE(通过LTE承载语音)是在LTE(长期演进)时代移动语音业务的终极解决方案。网络覆盖能力和用户容纳能力是移动运营商最为关注的两项网络指标。文章简单描述VoLTE的网络架构,重点介绍VoLTE采用的能够增强覆盖和容量能力的技术,通过理论计算以及与CDMA2000 1x和GSM的对比分析,证明相对现有移动语音承载方式,VoLTE无论在覆盖能力还是用户容纳能力上都具有非常显著的优势。 相似文献
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LTE采用全IP组网架构,取消传统电路域,如何在LTE网络上支持语音业务,成为热点研究问题,介绍多模双待、CSFB及VoLTE 3种LTE语音解决方案,详细阐述能够提供完美QoS保证的基于IMS的VolTE语音解决方案,在对VoLTE组网架构研究基础上,针对提供语音连续性保障的SRVCC及eSRVCC技术进行详细分析。 相似文献
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我国的移动通信网络技术历经多年的技术更新和演变,已发展成以VoLTE技术为代表的第四代移动通信技术.目前,VoLTE技术已日益受到重视和广泛应用.VoLTE技术的语音业务优势是4G移动通信时代的最大亮点,它具有比电路域回落方案(CSFB)和终端双待方案更明显的优势.在应用中,VoLTE技术经过了热点覆盖发展期、LTE网络连续覆盖发展期和LTE网络全覆盖发展期三个阶段.VoLTE技术在用户体验、语音接续力、应用范围与业务特性、频谱利用率与覆盖率以及应用成本等方面具有更大的网络优势. 相似文献
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VoLTE(基于IP多媒体子系统的语音业务)技术的应用是LTE发展的主要趋势之一,是LTE网络的最终语音解决方案。VoLTE的部署对于促进LTE网络演进具有重要作用,何时部署VoLTE以及如何部署Vo LTE对于运营商的业务发展具有重要意义。文章介绍VoLTE业务及产业链发展情况,对CSFB(电路域回落)、SVLTE(LTE与语音网同步)、OTT(Over the Top)等几种VoLTE部署前的语音过渡方案进行分析,指出运营商的网络现状及部署VoLTE面临的主要问题,对比几种过渡方案的特点,探讨运营商部署VoLTE的策略。 相似文献
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Meihua Shen Wilfred Pau Nicolas Gani Jianping Wen Shashank Deshmukh Thorsten Lill Jian Zhang Hanming Wu Guqing Xing 《半导体技术》2004,29(8)
This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration. 相似文献
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White organic light-emitting devices based on fac tris(2- phenylpyridine) iridium sensitized 5,6,11,12-tetraphenylnap -hthacene 总被引:1,自引:0,他引:1
We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4' -bis(2,2 -diphenyl vinyl)-1,1' - biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/NPBX (20 nm)/CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/NPBX (5 nm)/DPVBi (30 nm)/Alq(30 nm)/LiF(0.5 nm)/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N' -bis- (1-naphthyl)- N,N' -diphenyl -1, 1' -biphenyl-4,4' -diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (PPY)3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V. 相似文献
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Complete approach to automatic identification and subpixel center location for ellipse feature 总被引:1,自引:0,他引:1
XUE Ting WU Bin SUN Mei YE Sheng-hua 《光电子快报》2008,4(1):51-54
To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction. 相似文献
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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. 相似文献
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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. 相似文献
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Credence Systems Corporation 《半导体技术》2004,29(9)
Integrated circuits (ICs) intended for increasingly sophisticated automotive applications bring unique test demands. Advanced ICs for applications such as highly integrated automatic braking system (ABS) and airbag controllers combine high voltage digital channels, significant VI demands and precise timing capability. Along with continued missioncritical reliability concerns, the trend toward higher voltage operation and increased device integration requires specialized test capabilities able to extend across the wide operating ranges found in automotive applications. Among these capabilities, automotive test requirements increasingly dictate a need for a cost-effective versatile mixed-signal pin electronics with very high data rates reaching up to 50MHz with a voltage swing of-2 V to +28 V. 相似文献
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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. 相似文献
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YUXiao-hua XIANGYu-qun 《半导体技术》2005,30(2):30-32,37
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. 相似文献
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It is of interest to get appropriate information about the dynamic behaviour of rotating machinery parts in service. This paper presents an approach of optical vibration and deviation measurement of such parts. Essential of this method is an image derotator combined with a high speed camera or a laser doppler vibrometer (LDV). 相似文献