SDN技术及其在移动通信网中的应用

提出移动分组域网关控制面进一步分离以及面向用户和业务的智能路由两种在移动核心网引入软件定义网络(SDN)技术的思路,对移动分组域架构的演进展开了进一步思考;分析了数据中心内部和跨数据中心网络中可能的SDN应用场景,预测了SDN短期应用的可能性;分析了网络服务虚拟化的应用场景和关键技术.     

数据中心的网络虚拟化技术研究

文中以数据中心的网络虚拟化技术为研究对象，探讨了在现代数据中心环境下如何优化网络资源利用、提高网络性能和灵活性的问题。首先，引入了软件定义网络（Software Defined Networking，SDN）的基本概念与架构，分析了SDN与网络虚拟化的关系。在此基础上，设计了一个综合性的网络虚拟化总体架构，以支持多租户的虚拟网络隔离和灵活配置。随后，详细介绍了虚拟局域网（Virtual Local Area Network，VLAN）技术在该总体架构中的实现方法。为验证VLAN技术在数据中心网络中的效果，文中设计了实验环境并进行了实验评估。结果表明，VLAN技术有效提高了数据中心网络的资源利用率，提升了网络的灵活性和性能，验证了其在数据中心网络中的实用性和优越性。     

基于SDN的数据中心网络技术研究

随着云计算数据中心规模的扩大,虚拟化技术的成熟应用保证了计算能力、存储能力的自动伸缩,然而仍然采用传统网络技术,虚拟化程度严重不足,网络能力逐渐成为制约云计算灵活提供资源的瓶颈。SDN(Software Defined Network,软件定义网络)实现了控制与转发的分离,有效解决了网络资源的灵活配置问题。文章对现有SDN技术进行研究,重点分析基于SDN的数据中心网络技术,详细阐述SDN架构,并对控制器和转发设备进行分析说明,对理解基于SDN的数据中心网络具有借鉴意义,对SDN在数据中心落地提供了技术依据。其引入有效解决了数据中心的海量数据多路径转发、虚拟机智能迁移等网络问题,实现了对网络流量的智能规划。     

基于SDN的按需智能路由系统研究与验证

软件定义网络(SDN)是一种新型的网络技术,SDN开放可编程的理念与网络管道智能化的需求能够完美地契合。在基于SDN的下一代高智能网络(S-NICE)总体架构研究的基础上进行探索,论述了S-NICE架构中的核心系统——按需智能路由系统的关键技术、系统设计、部署验证和应用场景。     

SDN技术在电力企业数据中心应用的探索与研究

随着电力企业数据中心网络规模的不断增大和网络管理难度的不断提高,如何更有效地管理电力企业数据中心网络成为一项急迫的研究问题.面对这一问题,首先介绍了软件定义网络(software definednetworking,SDN)这一创新的网络架构技术,并着重对现有SDN在数据中心的部署方案进行了综述分析,最后以电力企业数据中心的云服务为实际案例,提出了SDN在电力企业数据中心尤其是桌面云池体系中的部署方案,并对其具体实施方式进行了探索及可行性分析.     

SDN

推荐理由：作为一种脱胎于Openflow技术的新的网络设计思路,2013年软件定义网络（SDN）的应用领域超越了数据中心（IDC）内部组网和路由交换设备内部设计,SDN所代表的＂网络开放性、虚拟化和可编程＂的理念开始在光网络、移动接入网络以及城域网中应用,受到了学术界和产业界越来越多的关注,技术路线竞争合作日益激烈,设备形态不断丰富,应用领域逐步拓宽,公司并购与重组频繁,SDN成为了近年来少有的技术热点,其对网络架构、设备形态、业务应用,以及网络运营企业、设备制造企业和互联网企业都将产生深远的影响。     

基于SDN的数据中心网络节能路由机制研究

新型数据中心大量采用"富连结"的网络拓扑,引入了大量交换机参与路由,造成大量能耗的出现,当前急切需要高效的网络节能机制,来降低数据中心网络的能耗并改善能量的使用效率。节能路由机制涉及到网络流量状态的收集和调配等问题,这些问题在SDN集中控制的架构下可以得到很好地支持。文章提出了一种基于SDN的数据中心网络节能路由机制,充分利用SDN集中控制的优势,非常好地满足了节能路由的需求。     

层次化跨区域SDN验证示范系统的设计与建设

软件定义网络（SDN）架构给网络带来了卓越的灵活性和可管理性。为了给新型SDN技术与应用提供大规模可行性验证试验床与试点部署平台,提出了依托于CERNET的层次化跨区域SDN 异地验证示范网络试验系统的总体架构,建设了9个城市、13个节点的SDN验证示范核心网与包含3个数据中心的接入网,并对基于SDN的vCPE智能专线业务、IPv4/IPv6过渡技术、流量监控调度应用和数据中心应用进行验证与示范。     

NFV和SDN在云数据中心的协同部署

为了解决云数据中心网络面临的诸多挑战,本文提出了一种NFV和SDN在云数据中心的协同解决方案,分析了部署方案中的关键网元,给出了NFV基于传统网络环境和基于overlay网络环境的两种部署架构,并分析NFV和SDN协同部署时需要重点关注的问题。     

基于SDN的云数据中心网络

随着云计算技术的发展和成熟,传统网络架构和技术已经难以适应云数据中心的发展.SDN技术为云数据中心网络部署提供了新的解决方案,被认为是云数据中心网络架构的未来演进方向.本文首先分析了云数据中心发展面临的主要问题和SDN技术特点,然后对比分析业界几种主流的SDN实现方案,考虑技术成熟度和部署难易的问题,深入分析了SDN Overlay方案,最后探讨了云数据中心网络的发展趋势.     

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