LTE网络端到端优化系统

LTE网络使用了64QAM调制,MIMO,OFDM等以往移动通信系统没有采用的新技术,给组网和优化带来新的困难。而且,我国决定先期使用2.6GHz频段用于TD-LTE组网,这个频段的无线传播特性比较差,在城市复杂的建筑与地形环境下,将给网络测试和优化带来巨大的挑战。传统的路测方法,很难覆盖所有的测试点,因此需要新的技术和手段来处理这个问题。端到端的网络优化方案,结合网络分析和传统路测的优点,能较好地解决这个问题。     

GPRS端到端优化思路的探讨

1前言GPRS移动通信系统是在原有的移动网络中引入了IP技术而形成的分组交换移动数据网络,真正实现了“无线+因特网”,率先满足了大众对移动多媒体的需求,但与常规的以电路交换型话音业务为主的移动通信系统相比,GPRS的网络结构、优化维护思路和方法有较大的差异。GPRS网络结构如图1所示。从图1可看出,由GPRS承载的服务要由无线网、核心网、外部因特网以及最终服务提供设备等多个方面共同提供,中间的任何环节出现问题均可能对用户造成影响。2GPRS的引入对移动网络优化的影响首先看一下移动网络中数据业务与话音业务有何区别:·数据…     

面向客户感知的集中性能端到端分析研究

以提升客户感知为出发点,需开展面向客户感知的端到端分析研究,推进对客户感知问题的发现、处理、评估的闭环管理。通过搭建性能指标体系、构建端到端分析方法、优化分析性能指标、跟踪问题处理解决等环节,逐步建立端到端分析闭环管控思路,并结合质量、感知、资源等多维度评估网络健康度,为网络短板排查提供有力支撑。     

基于端到端思维的LTE网络概率性感知差的优化研究

随着LTE网络规模迅速扩大,网络结构逐渐演变为2G/3G/4G并存的局面,网络覆盖不足、多网切换、同频干扰加剧等问题导致了用户感知差,特别是概率性的用户感知差问题不断增多。由于传统的路测/拨测优化手段在面对日益复杂的网络情况,越来越捉襟见肘。在这种情况下,端到端的网络优化思想就逐渐显露出优势。文章通过现网运营中发现的一些概率性用户感知差的问题进行详细分析,指出端到端思维在概率性用户感知差问题上的解决方式和方法,为后续4G网络优化提出一种解决困难的思路。     

移动互联网的端到端QoS的几点思考

移动互联网是互联网与移动通信系统的融合与发展,随着移动互联网的高速发展,用户对移动场景下的移动互联网服务质量及有线网络的服务质量的要求越来越高,希望可以实现移动互联网的无延迟、无阻塞、高质量服务。但由于移动网络的资源及拓扑结构具备动态性,这就增加了实现移动互联网端到端QoS的难度。为实现移动互联网中端到端QoS,就需要在移动互联网体系结构的基础上,解决移动管理、移动QoS协议、无线资源管理、分组调度等关键技术。     

5G NSA网络端到端差异化QoS策略研究

通过将不同的业务、用户映射到不同的QCI类型承载,并对不同的QCI类型承载配置不同的QoS参数,可以实现基于业务和用户的网络差异化服务。首先对NSA网络进行整体介绍,明确NSA网络无线承载类型,并逐一介绍相关的QoS参数。之后从业务差异化和用户差异化2个维度,制定相应的QoS策略,同时基于不同的策略,对无线网、传输网和核心网参数进行统一梳理,实现5G NSA网络端到端差异化QoS参数的合理化、标准化。     

Ixia展示面向LTE三重播放测试的端到端用户建模技术

聚合IP网络测试解决方案提供商Ixia,于2010年2月巴塞罗那移动通信世界大会期间,展示了如何使用Ixia的用户建模技术,实现对LTE节点和从无线到互联网核心整个网络的全面测试。用户建模通过配置真实用户的业务模型组合,     

基于802.16接入的端到端切换机制研究

对802.16无线接入网络的端到端切换机制进行了分析研究,结合802.16接入网络的特点,使用SIP协议实现端到端切换,提出了旨在减少切换时延和丢包的网络设计构架。     

IP城域网端到端QoS部署与优化研究

当前IP城域网负责的新业务给原本的网络传送方式带来了挑战,若想提升IP城域网负责业务的综合承载能力,则需要优化QoS技术。通过分析IP城域网端到端的QoS部署原则,围绕服务模式、分类、流量调整、网络拥塞解决等方面探究QoS部署和优化策略,为运营商解决QoS部署存在的问题并提供指导,总结QoS部署与优化策略的关键点。     

端到端重配置技术研究

端到端重配置技术起源于软件无线电,软件无线电技术实现了终端的多模式支持功能,并实现了软件从空中接口的下载.端到端重配置技术利用软件无线电提供的重配置能力,构建起以可重配置的终端、基站等网元为主体的体系结构,结合先进的动态网络规划、灵活频谱管理和联合无线资源管理技术,实现对重配置能力和异构无线资源的有效利用,保证用户的无缝业务体验.本文论述了端到端重配置技术的产生背景、基本概念和研究现状,对重配置研究中的主要问题和关键技术(包括架构、规划和管理等方面的内容)进行了系统的总结,最后就重配置未来研究的重点提出了自己的看法.     

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.     

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.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its