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1.
队列调度对于网络QoS至关重要。常见的多队列轮询调度算法对不同的输出队列设置不同的固定权值,这类算法在一定程度上能改善队列调度的公平性,但对于网络数据类型和流量变化较大的场合适应性较差。本文提出一种队列轮询权重自适应的方法,能较好的满足不同类型数据分组的QoS需求。  相似文献   

2.
基于Diffserv(区分服务)体系,研究实现QoS(服务质量)控制的核心技术之一的队列调度技术。基于WRR(加权轮询)队列调度算法,提出新型的改进算法。改进的队列调度算法主要由流量调节器和调度策略两部分构成,将网络上的包按照Diffserv体系分为EF(加速转发)、AF(保证转发)、BE(尽力服务)三种业务类型,对不同的类型采用不同的调度策略。针对高优先级的EF业务直接采用PRI(优先级调度),针对AF业务采用改进后的WRR调度。仿真结果表明,该改进型调度算法在网络资源分配上具有一定的优越性。  相似文献   

3.
目前已提出的HSDPA调度算法仅是基于用户的优先级进行数据分组的调度.文章考虑了3G系统的业务多样性,综合考虑用户的优先级和业务的级别,创新性地提出将两类分组调度算法,即基于业务类别的分组调度算法--加权公平排队算法,与基于用户优先级的调度算法--最短队列算法或者最长队列算法相结合后的调度算法.仿真的结果显示,提出的调度算法能满足不同业务要求的QoS.从吞吐量和延时来看,最短队列算法与加权公平排队算法结合方案优于最长队列算法与加权公平排队算法结合的方案.  相似文献   

4.
介绍了包交换芯片流量管理中队列调度的算法,分析DWRR(Deficit Weighted Round-Robin)算法的优缺点,并提出了一种基于DWRR改进的调度算法.该算法能够根据网络中实时的数据包帧长,来调节每次轮询中向各个队列添加的信用度,能够减少各个队列的时延,同时又增强带宽分配的相对公平性,改善了DWRR算法不能很好满足业务的时延特性.使用NS-2仿真器来对改进的算法进行网络仿真,最终的仿真结果表明改进后的DWRR算法能够有效地降低时延,可以在一定程度上提高QoS.  相似文献   

5.
首先介绍了队列调度算法在流量控制中的关键地位,然后讨论了现有队列调度算法,如基于优先级的调度算法、轮询调度算法与公平队列调度算法,最后提出了一种新的队列规程,该队列规程融合了优先级调度算法与DRR调度算法。在网络正常情况下,不同业务流公平地共享网络带宽,在网络出现拥塞的情况下,高优先级业务流能够抢占带宽,保证其较低的丢包率,并能够实现两种调度算法的快速切换。  相似文献   

6.
文章简要介绍了网络处理器及常见的队列调度算法,设计完成了基于网络处理器的队列调度策略.有效实现了不同数据流的服务质量控制。  相似文献   

7.
一种适用于宽带无线IP网络的分组调度算法   总被引:3,自引:0,他引:3       下载免费PDF全文
纪阳  李迎阳  邓钢  胡健栋  张平 《电子学报》2003,31(5):742-746
自适应调制技术在许多新型的无线分组网络如WCDMA HSDPA、HiperLAN/2中得到广泛采用.本文在充分考虑自适应调制系统链路带宽随时隙呈不平均分布特点的基础上,提出一种全新的调度算法,自适应区分补偿公平队列(ADCFQ).该算法采用了基于工作量的分析方法,设计了不同功能的多个子队列,可以为系统所有待发流提供基本的QoS保证,为各个流公平共享剩余带宽,并能够通过合理的补偿机制克服无线环境中突发错误影响.分析和仿真结果表明,这一算法可以满足目标要求.此外,仿真中,针对自适应链路的特点,本文还提出了一种基于多状态Markov链的信道建模方法.  相似文献   

8.
在无线Mesh网络中,支持QoS的IEEE 802.11eEDCA协议,其固定的队列接入机制,使得在网络负载较重的时高优先业务的QoS得不到应有的保障,同时在网络负载较轻时信道利用率也不高.文中提出了一种动态调整业务接入队列的算法.节点可以根据感知到的网络负载状况自适应调整队列接入方式,在保障高优先级业务QoS要求的同时,尽可能提高信道的利用率.仿真结果表明,在不同网络负载的场景下,该算法相对于IEEE802.11e在QoS保障和利用率方面都有较好的表现.  相似文献   

9.
本首先介绍了在Internet中实现QoS的必要性,然后从支持协议,调度算法,队列管理和流量工程等几个方面探讨了QoS的实现机制,最后给出了高速网络节点中QoS实现的一种结构。  相似文献   

10.
首先介绍了在TD-HSUPA系统中调度算法对无线资源管理的重要影响及Node B调度的基本原理.然后分析了几种常用的无QoS保证的调度算法和两种保证多业务QoS的调度算法,并通过公平性、吞吐量等性能指标对它们进行分析比较.最后引入了经济学中的效用函数思想,分析了基于效用函数的调度算法,它能够结合相应业务的QoS要求,更加真实地反应用户的满意情况,为调度算法的改进提供依据,从而使网络能够承载更高的数据服务容量,增强网络建设的有效性.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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   

16.
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   

17.
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   

18.
A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.  相似文献   

19.
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   

20.
A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.  相似文献   

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