WLAN_MESH中一种基于负载均衡的接入点选择方法

针对WLAN Mesh网络进行接入点选择方法设计时,传统的接入方法以RSSI强度作为接入判断准则存在的缺陷问题,本文提出一种基于负载均衡的接入点选择方法,通过在负载均衡器中添加负载控制模块对网络和节点的负载进行实时监控,并建立网络效用模型,确定联合网络收益最大所对应的每个网络的接入用户数量,使得网络之间负载均衡且联合收益最大化。     

基于模糊神经网络的异构无线网络接入选择算法

针对现有异构无线网络基于模糊逻辑及神经网络的接入选择方法未能合理考虑网络负载状况的问题,提出一种基于RBF(径向基函数)模糊神经网络的接入选择方法.该方法以可接入网络的接入阻塞率相等为模糊神经网络参数强化学习的目标,对网络负载程度具有很好的动态适应性,实现了智能化的接入判决.仿真结果表明,该方法能有效均衡异构无线网络间的负载,保障实时与非实时业务的QoS,并且相对于负载均衡算法(MLB算法)降低了网络的接入阻塞率.     

多层立体网络基于用户特征的切换方法

文中提出了一种多层立体网络中基于用户特征的切换方法,以天地一体的用户接入和通信过程为主要研究对象,提出了在多层立体网络中用户切换的方法与实现过程。切换方法考虑了接入点的基础条件、用户特征和相对移动性,以提高负载均衡和降低切换次数等作为设计目标,降低了切换对网络的影响,提高了网络的可控性与安全性。该方法可用于未来天地一体多层立体网络中,实现多种接入方式的优化选择与无缝切换。     

基于负载均衡的中继选择和频谱转移联合优化策略

针对负载失衡或热点覆盖无线中继网络,提出一种基于负载均衡的自适应中继选择和频谱转移联合优化策略。定义了一种衡量一个站点对周围同频站点干扰程度的干扰容量,为某站点对其他站点的干扰提供了量化分析指标。当用户申请接入时,首先根据各条链路的信道状况选择首选接入站点和备选接入站点,当首选接入站点负载过重而无足够资源使其接入时,对接入备选站点和从与首选站点同扇区的其他站点向首选站点进行频谱转移的性能进行比较,选择一种维持系统性能较好的方式接入。仿真结果表明,所提算法在中心小区的频谱效率和阻塞率都优于单一的基于负载均衡的中继选择策略和单一的基于负载均衡的频谱转移策略,并且平均干扰容量也最低,对周围小区的系统性能影响较小。     

北电网络推出面向企业和运营商的WLAN产品系列 进一步补充北电网络WLAN战略 提高安全性并改进无线漫游

北电网络近日推出一系列面向企业和运营商的新型无线局域网 (WLAN)产品。该产品系列旨在安全地提供高带宽话音和数据业务 ,使最终用户能够通过个人计算机 (PC)、手持设备或蜂窝电话随时随地接入各种应用。北电网络WLAN产品系列将包括四种核心产品 :安全交换机 2 2 5 0 :提供安全性管理业务 ,如基于权限的接入、非法接入检测以及中央控制保护和管理WLAN上的移动通信。此外 ,负载均衡功能将提供更高效的流量分配和带宽管理功能 ;使网络管理员最大限度地提高网络可用性。接入点 2 2 2 0 :为有线以太网络提供基本安全性且功能丰富的接入点…     

基于5G无人机通信的多智能体异构网络选择方法

摘 要：5G无人机通信网络和各种不同无线接入技术的结合使无线异构网络呈现多样化的发展趋势。然而，用户繁多且不同的业务请求对网络要求也不同，造成网络接入选择问题。提出了一种基于5G无人机通信的多智能体异构网络选择方法，将用户分为多个智能体，从用户端和网络端两个方面出发，将用户侧的时延和传输速率需求与网络侧的负载均衡需求综合考虑作为即时回报的相关参数，通过基于Nash Q-Learning的算法进行学习，得到异构网络环境下的网络选择决策模型。仿真结果表明，所提异构网络选择方法针对不同业务类型用户的需求均能选择合适的网络，同时均衡网络的负载，充分利用异构无线网络的资源。     

异构无线网络多用户多业务接入中多目标优化控制方法研究

针对多异构网络重叠覆盖、多用户多业务共存环境下,用户最大化传输速率易致网络负载不均衡的问题,提出一种基于非支配排序遗传算法的业务接入控制方法。该方法首先以传输速率最大化及网络负载最均衡为目标,以带宽资源受限为约束,构建了传输速率最大化及网络负载最均衡的双目标优化模型;然后基于多目标优化方法非支配排序遗传算法(Non-dominated Sorting Genetic AlgorithmⅡ,NSGA-Ⅱ)求解该业务接入控制问题。仿真结果表明,所提算法兼顾了用户的传输速率需求及网络间的负载均衡,取得较好的效果。     

无蜂窝大规模MIMO中基于深度强化学习的无人机辅助通信与资源调度

无蜂窝大规模多入多出(MIMO)网络中分布式接入点(AP)同时服务多个用户,可以实现较大区域内虚拟MIMO的大容量传输;而无人机辅助通信能够为该目标区域热点或边缘用户提供覆盖增强.为了降低反馈链路负载,并有效提升无人机辅助通信的频谱利用率,该文研究了基于AP功率分配、无人机服务区选择和接入用户选择的联合调度;首先将AP...     

LTE-A系统中继网络中接入点选择算法的研究

LTE-A系统中引入中继技术后,用户可以根据不同的接入点选择算法选择接入基站或中继。传统的接入点选择算法只是直接对比接入链路和直接链路的链路质量,选择质量较好的一条链路接入,并没有考虑到选择接入中继时会在回程链路消耗额外的无线资源,因此并不能选择一个能够使系统单位带宽传输数据量较大的接入点进行接入。针对上述问题,文中提出了基于两跳链路的接入点选择算法,它综合考虑了链路质量和消耗的无线资源,然后选择相应的接入点。仿真结果表明新提出的接入点选择算法可以提高系统吞吐量。     

基于改进蚁群算法的软件定义网络负载均衡

为改善软件定义网络(SDN)负载均衡问题,对传统的蚁群算法进行改进,并结合服务器负载均衡算法,提出一个改进型的联合算法。该算法使用加权最小连接调度算法,服务器端选择负载最小的服务器,并利用改进蚁群算法(Im-ACO)选择到达所选服务器的最佳路径。理论分析及实验结果表明,提出的联合算法使网络性能得到显著提高,网络吞吐量更高,丢包率更低。     

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.     

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.     

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.     

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.     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.