弹性分组环带宽公平分配方案的优化设计

在弹性分组环(RPR)各源节点公平性基础上,提出一种MAC层带宽公平分配的优化方案来确保RPR网络的稳定.该方案通过采集源节点信息来计算公平速率,以此调整源聚合流及各个链路速率,从而实现整个RPR环网的公平性,达到高的链路带宽利用率.仿真结果显示,该方法能够针对非平衡流优化RPR网络中的带宽分配,是有效的公平分配方案.     

RPR技术及其QoS分析

弹性分组环(RPR)是目前在城域网中进行数据传输的一种新的传输技术。网络的服务质量(QoS)是下一代IP光因特网中一个很重要的问题。RPR作为一种新的光传输技术,必须支持QoS。基于此,主要介绍了RPR网络特点,并回顾和总结了已有的RPR网络QoS方案。最后,提出了MPLSoverRPR的QoS方案。     

基于IXP2400的RPR综合业务接入系统设计

介绍了IXP2400网络处理器的结构特点,提出了一种基于IXP2400的弹性分组环(RPR)综合业务接入系统方案,可接入千兆以太网和弹性分组环等宽带业务,并说明了利用该接入系统构建弹性分组环站点和实验网络的方法.     

弹性以太环节点设计方案

提出一种基于IEEE802.17标准和IEEE802.3标准的弹性以太环节点设计方案,以及主要模块详细的功能设计,并给出了弹性以太环节点验证系统的设计方案.该方案既有效利用了RPR的特点,又实现了在城域网络中传输以太网数据和有效降低城域网络建设成本的目的.     

弹性分组星-环的研究

弹性分组环(RPR)是城域网发展的关键技术,基于环形结构存在的局限性,提出了一种融合RPR和WDM技术的弹性分组星-环方案:将环形结构和星形结构结合起来,组成一个四环结构,外二环是标准的RPR环,内二环在逻辑上则是星形结构,分析结果显示该结构在传播时延,吞吐量,链路利用率,平均跳距和扩展性等方面都比传统的RPR具有优越性.     

RPR环网中的一种带宽公平分配算法

首先讨论了RPR网络中的公平性原则,然后结合该原则引入了一种适合于RPR网络的公平分配方案,基于该方案提出了一种能满足RPR环网性能要求的公平分配算法。该算法通过采用控制的方法为共享某链路的各数据流合理地分配带宽资源,从而达到:(1)各流的速率达到稳定;(2)链路缓存的占有量稳定到一个目标值;(3)链路带宽得到充分利用且实现公平分配。同时该算法能顺次协同地处理完网络中的各个链路,从而能够实现整个RPR环网的公平性与高的链路带宽利用率,达到RPR协议所要求的目标。给出了该算法的代码描述并对其作出稳定性分析,然后通过仿真对其性能进行了验证。     

RPR软硬件协同验证平台设计(本期优秀论文)

提出了一种低成本、省时且简便易行的软硬件协同验证平台,用以实现完整的RPR芯片验证工作.该验证平台还可用于RPR样片的功能测试.借助于该平台实验室已经成功开发了具有独立自主知识产权的RPR MAC层专用芯片--MX10GRPR-71.     

弹性分组环(RPR)芯片的一种实现方案

发展弹性分组环(Resilient Packet Ring RPR)技术要依赖专用集成电路.给出了一种完全符合802.17标准的RPR专用集成电路设计方案,以及主要模块详细的功能设计,并给出了芯片验证系统的设计方案.此芯片设计方案满足标准性、通用性、可扩展性,其验证系统可以实现几种不同的RPR组网方式.目前,此芯片方案已经进入组环验证阶段.     

华中电力光环网组网案例分析

光同步传送网(SDH)是20世纪80年代后期提出来的一种新的数字传输体系,当时电信网正处于电话网占主导地位的时代,所以SDH具有固定比特率、电路交换、面向连接等"基因"。弹性分组环(RPR)是2000年提出来的适合于城域网的新传输技术。进入新世纪的电信网是多业务网,数据业务量已接近电话业务量,并在几年内超过。RPR能适应这种变化,经济有效、灵活可靠地接入和传送各种业务。实现RPR功能有几种方案,其中在SDH设备中嵌入RPR功能是已实用化的方案之一,该方案具有SDH和以太网两种技术优点。北电网络车轮奔先生所撰《华中电力光环网组网案例分析》一文有助于读者了解北电网络内嵌RPR的SDH产品在华中电力的成功应用,值得一读。     

基于Inte1网络处理器实现弹性分组环交换节点

在阐述了RPR交换节点软件结构之后介绍了使用Intel IXP2800实现网络设备的优势,最后总结了IXP2800数据平面开发的一些方法和经验.实践表明基于Intel IXP2800网络处理器设计并实现RPR交换节点是一种可行的方案.     

一种配电自动化分组光环网的设计

设计了一种适用于配电自动化以及相似环境的通信网络,它由双光纤环构成,使用GFP协议封装信息,在环上传递分组。此网络接入灵活、路由机制简单、支持QoS和流量控制、保护恢复迅速。测试表明本系统具有较高的链路利用率、低传输时延和恢复时间。目前生产的设备在小规模网络环境下运行正常。     

The second-order magnetization precession in an anisotropic medium. Part 2: The cubic anisotropy

The second-order precession of the magnetization vector in a normally magnetized magnetic plate with the cubic anisotropy is considered for the [001], [011], and [111] orientations of the axes of a cubic cell along the static field. The precession pattern of the forced oscillation in the form of a large ring and small rings located along the envelope is obtained. A relationship between the observed high- and low-density groups of small rings and the spatial position of the [111] easy magnetization axes is revealed and explained on the basis of the energy model of the potential. It is found that the phenomenon is highly sensitive to the orientation of cubic axes, the anisotropy constant, and the intensities and directions of the static and alternating fields. It is reported that the observed phenomena can be used in practice.     

Dispersion-flattened Bragg photonic crystal fiber for large capacity optical communication system

A novelty dispersion ultra-flattened Bragg photonic crystal fiber (PCF) has been fabricated in this paper.The fiber is composed of compound cores and periodical claddings with 11 coaxial rings.It has flattened dispersion of 8.54±1.3 ps-(nm· km)-1 in the communication wavelength range of 1460-1625 nm.Its dispersion slope alters from -0.0428 to 0.0392ps·nm-2·km-1.The low attenuation of 0.52 dB/km and low bending loss of 0.09 dB at 1550 nm of the fiber are also achieved.The Bragg PCF has enormously potential application in the fields of dense wavelength division multiplexing systems because of its superior dispersion properties and easy splicing performances.     

SONET ring applications for survivable fiber loop networks

Synchronous optical network (SONET) self-healing rings (SHR) are studied in the loop environment. SONET SHR architectures for loop feeder networks are discussed, focusing on three possible dual central office (CO) architectures for fiber loop networks, using SONET SHRs to reduce network costs and provide network service survivability. These architectures reflect an integrated planning concept for SONET networks that eliminates the boundary between the access network and the inter-office network. It is shown that the use of SONET SHRs makes it easy to evolve to a protected dual CO access architecture. Economic and survivability studies are discussed. The economic studies show that using the ring approach yields significant advantages over the traditional diverse protection approach in terms of cost and survivability, especially for the dual CO architectures     

Fast optical Layer mesh protection using pre-cross-connected trails

Conventional optical networks are based on SONET rings, but since rings are known to use bandwidth inefficiently, there has been much research into shared mesh protection, which promises significant bandwidth savings. Unfortunately, most shared mesh protection schemes cannot guarantee that failed traffic will be restored within the 50-ms timeframe that SONET standards specify. A notable exception is the p-cycle scheme of Grover and Stamatelakis. We argue, however, that p-cycles have certain limitations, e.g., there is no easy way to adapt p-cycles to a path-based protection scheme, and p-cycles seem more suited to static traffic than to dynamic traffic. In this paper we show that the key to fast restoration times is not a ring-like topology per se, but rather the ability to pre-cross-connect protection paths. This leads to the concept of a pre-cross-connected trail or PXT, which is a structure that is more flexible than rings and that adapts readily to both path-based and link-based schemes and to both static and dynamic traffic. The PXT protection scheme achieves fast restoration speeds, and our simulations, which have been carefully chosen using ideas from experimental design theory, show that the bandwidth efficiency of the PXT protection scheme is comparable to that of conventional shared mesh protection schemes.     

减少测粒仪光靶环数提高颗粒尺寸求解速度

本文指出当采用函数限制解法求解颗粒尺寸分布时,仅用光靶上的少数几个环就能确定分布函数,而且得到与原来(15个环)相同的可测粒径范围和对颗粒尺寸变化的灵敏度,文中对此进行了理论分析和计算机模拟计算,并给出了对标准颗粒的实测结果。     

Miniaturized coplanar waveguide stop band filters based on multiple tuned split ring resonators

A novel compact stop band filter consisting of a 50 /spl Omega/ coplanar waveguide (CPW) with split ring resonators (SRRs) etched in the back side of the substrate is presented. By aligning SRRs with the slots, a high inductive coupling between line and rings is achieved, with the result of a sharp and narrow rejection band in the vicinity of the resonant frequency of the rings. In order to widen the stop band of the filter, several ring pairs tuned at equally spaced frequencies within the desired gap are cascaded. The frequency response measured in the fabricated prototype device exhibits pronounced slopes at either side of the stop band and near 0 dBs insertion loss outside that band. Since SRR dimensions are much smaller than signal wavelength, the proposed filters are extremely compact and can be used to reject frequency parasitics in CPW structures by simply patterning properly tuned SRRs in the back side metal. Additional advantages are easy fabrication and compatibility with MMIC or PCB technology.     

偏振不敏感的九聚物太赫兹超材料

在实验上提出将九个开口谐振环以第一个谐振环的开口方向为基准按照涡旋状的轨迹排布,且依次将开口环逆时针扭转40,构成九聚物太赫兹超材料,并在理论上系统研究了该超材料的传输特性。将原本只具有单一谐振模式的开口谐振环按照类似于低聚物的结构排布方式构成周期单元结构时,利用结构末端引起的能量耦合来增强相邻谐振器间的能量耦合,便会有更多的谐振模式产生,最终实现偏振不敏感的效果。这种思路丰富了传统超材料离散结构的设计理念,为太赫兹超材料功能器件,如开关,调制器和滤波器等的设计提供了一种新的参考方案。     

Vibrational spectroscopy of amorphous carbon modified with Pt

IR absorption spectra of films of amorphous carbon (a-C) and a platinum-modified nanocomposite based on amorphous carbon (a-C:Pt) have been studied in the range of stretching vibrations of the carbon skeleton (1200–1700 cm^?1) and bending vibrations of C-H bonds (2700–3100 cm^?1). It is shown that modification of amorphous carbon with platinum gives rise to an absorption band at 1500 cm^?1, which is attributed to platinum-induced destruction of graphene rings of graphite-like fragments into isolated benzene rings. It is concluded that hydrogen “cross-links” benzene rings into graphene clusters, whereas platinum “de-cross-links” graphene clusters.     

基于CSRR 改进的双陷波超宽带天线

针对超宽带系统易受窄带信号干扰的问题,提出了一种基于互补金属开口谐振环(CSRR)改进的双陷波超宽带缝隙天线。在现有文献中,单个CSRR只能实现单陷波功能,要想增加陷波频段,只能通过增加CSRR个数的方法来实现,这就增加了设计的复杂性。通过天线辐射贴片上的表面电流分布图分析了CSRR内外环与两个陷波频段的对应关系。对所设计的超宽带天线进行了制作和测量,实测结果与仿真结果吻合较好,证明了该设计方法的正确性。