Optimum signal wavelength for a distributed erbium-doped fiberamplifier

Theoretical analysis of a 100-km-long transparent germanosilicate distributed erbium-doped optical fiber has been carried out. It is shown that the optimum signal wavelength is 1.554 μm both considering the noise performance and the necessary pump power for achieving unity gain when the distributed erbium-doped fibers are pumped at 1.48 μm     

面向分布式网络数据的容错控制策略

随着多核处理器核心数量的增多,系统容量的扩大,在制造和运行过程中产生的故障将会增多,容错能力对于系统的可靠性将变得更加重要。而一个片上系统的正常工作,将会非常依赖于片上网络系统传输数据的可靠性。芯片的制造偏差和组件故障、多处理器系统芯片集成不规则IP以及动态的电源门控都将导致片上网络中出现不规则拓扑结构。片上网络应当具备可以重新配置网络路由方式并将数据传输路径绕过无法正常工作的位置。文中设计了一种用于路由计算的特定约束跳转配置方法,为了保证其健壮性,采用基于局部信息的通信方式,设计实现了分布式的路由器传输路径配置单元,并完成了该方法的算法实现。     

WASPNET: a wavelength switched packet network

WASPNET is an EPSRC-funded collaboration between three British Universities: the University of Strathclyde, Essex University, and Bristol University, supported by a number of industrial institutions. The project which is investigating a novel packet-based optical WDM transport network-involves determining the management, systems, and devices ramifications of a new network control scheme, SCWP, which is flexible and simplifies optical hardware requirements. The principal objective of the project is to understand the advantages and potential of optical packet switching compared to the conventional electronic approach. Several schemes for packet header implementation are described, using subcarrier multiplexing, separate wave lengths, and serial transmission. A novel node design is introduced, based on wavelength router devices, which reduce loss, hence reducing booster amplifier gain and concomitant ASE noise. The fabrication of these devices, and also wavelength converters, are described. A photonic packet switching testbed is detailed which will allow the ideas developed within WASPNET to be tested in practice, permitting the practical problems of their implementation to be determined     

基于大数据的分布式网络安全管理平台的设计

随着企业信息化程度与安全意识的不断提高,企业部署了大量的信息安全设备与安全监控系统用于企业信息安全防护,同时也带了海量的信息安全数据。面对如此大规模的信息安全数据,传统的安全管理平台显得力不从心,近年来随着各种基于针对大数据处理的分布式开源组件在互联网行业广泛的推广与应用,也为海量信息安全数据处理提供了一种新的思路。因此,文中提出了一种基于大数据的分布式网络安全管理平台的设计,平台是一套基于分布式文件系统的开源架构,以Kafka为数据收集工具,使用Hbase和My SQL作为多源异构数据数据库,结合Storm和Elastic Search进行实时处理与检索,并通过实验验证了平台的快速检索与关联分析能力,为企业部署大数据安全管理平台提供有力的依据。     

Intelligent network: a distributed system

The aspects of a distributed system that must be introduced into a telephone system to achieve the objectives of the intelligent network are explored. Several of these distributed constructs are discussed, namely, hierarchically controlled replicated data, precontrolled replicated data, and distributed nonreplicated data. It is shown by examining an actual or a theoretical service why each of these constructs could be advantageous to have in the intelligent network architecture. Various aspects of implementing these constructs in the telephone network are examined     

An evaluation of distributed wavelength provisioning in WDM optical networks with sparse wavelength conversion

Distributed wavelength provisioning is becoming one of the most important technologies for supporting next-generation optical networks. This paper describes the evaluation of the performance of distributed wavelength provisioning in wavelength-division-multiplexing (WDM) optical networks with sparse wavelength conversion (i.e., where wavelength conversion is available at only a subset of network nodes). Using the well-known destination-initiated reservation method as a case study, a highly accurate analytical model supported by comprehensive simulation validation is proposed. Both analytical and simulation results show that, in optical networks with distributed wavelength provisioning, sparse wavelength conversion still helps to significantly lower the connection-blocking probabilities. However, unlike that in centralized wavelength provisioning, sparse wavelength conversion may not easily achieve nearly the same performance as that of full wavelength conversion, especially under light traffic loads. This paper evaluates how the potential contribution of sparse wavelength conversion depends on different factors, such as the number of wavelength converters, the number of wavelength channels per fiber, the burstiness of traffic loads, and the network size, and discusses the influence of the signaling scheme.     

Optimized in-band control channel with channel selection scheduling and network coding in distributed cognitive radio networks

This article proposes an optimized in-band control channel scheme with channel selection scheduling algorithm and network coding based transmission paradigm in the distributed cognitive radio network (...     

Broad wavelength tuning under single-mode oscillation with a multi-electrode distributed feedback laser

Broad wavelength tuning under single-mode oscillation is achieved for a 1.5 ?m range multi-electrode distributed feedback laser. The lasing wavelength can be tuned electrically, maintaining a stable single-mode oscillation without mode jumping. The tuning has reached over 20 ? under a noticeable condition of constant power (5mW), with a sufficient side-mode suppression ratio over 30 dB.     

基于分布式网络的1553B数据处理软件设计与实现

为了解决当前1553B数据处理单机软件制约海量数据情况下多课题并行处理效率的现状,在此采用基于Web的分布式中间件技术,将1553B数据处理软件开发成基于分布式网络的标准数据处理中间件。为保持参数名的惟一性,以ICD文件中的消息规范名为数据库中的参数名称,并且编写了该软件与飞行试验数据网络处理系统(FTDPS)的标准数据接口文件,根据分布式中间件的调用流程设计了相应的算法,最终实现100%1553B数据的网络化并行处理,极大地提高了总线数据处理效率。     

Optimized distributed MIMO for cooperative relay networks

This paper presents an optimized distributed multiple-inputmultiple-output (OD-MIMO) for cooperative communication in wireless relay networks. The set of cooperating nodes is a priori unknown. In order to avoid the centralized stream and pilot allocation procedure, a fixed signature vector (SV) is assigned for each node in the network. We analyze the constraints of the proposed scheme, and derive an optimization criterion for the decision of the SVs. A gradient-based algorithm for SV design is provided. Simulation results show that the performance loss of OD-MIMO compared to centralized distributed MIMO is small for large number of cooperative relay nodes.     

Detecting disruptive routers: a distributed network monitoringapproach

An attractive target for a computer system attacker is the router. An attacker in control of a router can disrupt communication by dropping or misrouting packets passing through the router. We present a protocol called WATCHERS which detects and reacts to routers that drop or misroute packets. WATCHERS is based on the principle of conservation of flow in a network: all data bytes sent into a node, and not destined for that node, are expected to exit the node. WATCHERS tracks this flow, and detects routers that violate the conservation principle. We show that WATCHERS has several advantages over existing network monitoring techniques. We discuss WATCHERS response to several different types of bad router behavior. We demonstrate that in ideal conditions WATCHERS makes no false positive diagnoses, and we describe how WATCHERS can be tuned to perform nearly as well in realistic conditions. Also, we argue that WATCHERS impact on router performance and WATCHERS memory requirements are reasonable for many environments     

Collaborative sensing in a distributed PTZ camera network

The performance of dynamic scene algorithms often suffers because of the inability to effectively acquire features on the targets, particularly when they are distributed over a wide field of view. In this paper, we propose an integrated analysis and control framework for a pan, tilt, zoom (PTZ) camera network in order to maximize various scene understanding performance criteria (e.g., tracking accuracy, best shot, and image resolution) through dynamic camera-to-target assignment and efficient feature acquisition. Moreover, we consider the situation where processing is distributed across the network since it is often unrealistic to have all the image data at a central location. In such situations, the cameras, although autonomous, must collaborate among themselves because each camera's PTZ parameter entails constraints on the others. Motivated by recent work in cooperative control of sensor networks, we propose a distributed optimization strategy, which can be modeled as a game involving the cameras and targets. The cameras gain by reducing the error covariance of the tracked targets or through higher resolution feature acquisition, which, however, comes at the risk of losing the dynamic target. Through the optimization of this reward-versus-risk tradeoff, we are able to control the PTZ parameters of the cameras and assign them to targets dynamically. The tracks, upon which the control algorithm is dependent, are obtained through a consensus estimation algorithm whereby cameras can arrive at a consensus on the state of each target through a negotiation strategy. We analyze the performance of this collaborative sensing strategy in active camera networks in a simulation environment, as well as a real-life camera network.     

适用于波长交换光网络（WSON）的波长旋转图模型设计

将网络虚拓扑链路及关联波长均匀分布到旋转球体的表面,建立了新型的波长交换光网络(WSON)的波长旋转图模型,并基于旋转图模型提出了路由波长分配(RWA)新策略及算法.仿真结果表明,每条链路的总波长数分别为4和8时,新策略算法的阻塞率平均降低5.03%和9.71%,资源利用率平均提高3.3%和1.54%.该模型用于解决具有波长转换能力的RWA问题效果明显.     

一种用于波长路由光网络的分布式快速波长预留协议

波长预留协议用于在光通道建立过程中预留和配置波长.目前已有的波长预留协议都把协议设计的目标定为降低网络阻塞率,没有一种协议设计把目标定为缩短光通道的建立时间和简化协议处理过程.然而更短的建立时间和更小的协议复杂度对于未来极其动态的光网络却是非常重要的.提出了一种新颖的用于波长路由光网络的分布式快速波长预留协议-目的端预留协议,它在保证网络阻塞率可以接受的前提下,不仅可以降低连接建立时间,还可以减少控制节点处理器需要处理的信令消息数量.仿真结果证明了这一点.     

Logical process partitioning in distributed simulation using genetic algorithms

This paper presents a method to partition models in logical processes in the context of distributed simulation. The proposed method uses genetic algorithms to decide on the viability and the partitioning technique most indicated. The input parameters to the genetic algorithm are information about the model (number of elements, communication, arrival and service taxes), and the architecture where the simulation is executed. As result, we have the number of logical processes and their mapping on the distributed environment. Two models were used to evaluate the proposed method.     

Realization of all-pass characteristics utilizing a distributed RC network

An active network is described which incorporates lumped and distributed RC elements in order to realize all-pass transfer functions.     

Analysis of a λ/4-phase-shifted doublephase-shift-controlled distributed feedback wavelength tunable opticalfilter

We have proposed a new λ/4-phase-shifted double phase-shift-controlled distributed feedback wavelength tunable optical filter structure. Theoretical analysis based on the transfer matrix method reveals that this filter can achieved a wavelength tuning range of 28.3 and 34.3 Å for the grating coupling coefficients of 6 and 10 mm, respectively. The filter has almost constant peak transmissivity (gain) of more than 30 dB within its tuning range, and its side-mode suppression ratio (SMSR) ranges from 15 to 34.7 dB     

XGM波长变换器网络的路由波长分配算法研究

交叉增益调制(XGM,Cross-Gain Modulation),用于波长变换技术,可较简单地制成全光波长变换器。该文先用一个简单的近似模型分析了XGM波长变换器对路径阻塞率的影响,进而根据其本身固有的特点,设计了3种适合于XGM波长变换器网络的路由波长分配算法。通过在美国科学基金会骨干网络(NSFNET,National Science Foundation backbone network),和网孔型(Mesh-torus)网络中的仿真,从网络的阻塞率和公平性两个方面研究XGM波长变换器对网络性能的影响,同时比较了3种算法的性能。仿真结果表明,XGM波长变换器较无波长变换,可以在网络的阻塞率和公平性两个方面都得到较大的改善;3种算法中,FF/lowest算法在改善网络的阻塞率和公平性两个方面都是最优的。     

Applying a 3-D-GUI to a distributed network management system

Three-dimensional (3-D) GUIs help network operators to understand complicated network configurations. With the goal of applying 3-D-GUI technology to CORBA-based network management systems, this paper proposes a method of integrating VRML/Java/CORBA, in which Java applets mediate management information between a VRML scene and a CORBA server. A prototype system configuration that incorporates this method and its operation sequence, which displays the fault notifications on VRML scenes, is described. An evaluation of the prototype system demonstrates the effectiveness of this method