LOCNET--A local area network using optical switching

A wide-band local area network using optical switching is presently being developed by the Heinrich-Hertz-lnsitut in Berlin (West). To ensure high reliability the system will be implemented as a star type network, divided into two subsystems. All switching within the system will be done by optical switching techniques. The wide-band subsystem will use Lithium-Niobate switching matrix elements, interconnected as a multistage space switch. Thus bit rate independent channels will be available with the ability to establish various wide-band services of the in-house area. The second subsystem makes use of a single-mode star coupler. Distributed circuit switching with fast switching capability and flexible data rates will be implemented, utilizing a TDM frame, that supports 63 narrow-band connections and a capacity of 8 Mbit/s for fast data services. To prevent typical disadvantages of distributed switching like line tapping and system disturbance, caused by malfunctioning system components, LiNbO3switches will be installed in front of and behind the star coupler. The single-mode star coupler will be implemented by cascading 2 × 2 star couplers, which are available as 3-dB couplers.     

基于GMPLS的光突发交换体系及其关键技术

文章给出了基于通用多协议标签交换(GMPLS)的光突发交换(OBS)对等体系(GLOBS)的功能结构和分层视图.在此范畴内,针对标签空间减小和流量工程两方面,结合国内外最新的研究动态,比较了各种已有技术的优缺点,并提出了适合于GLOBS体系的可能的解决方案以及今后工作的重要技术问题.     

A new distribution network based on controlled switching elementsand its applications

The paper presents a new distribution network which is capable of concentrating and shifting the incoming active packets simultaneously, without requiring dummy destination address generation and extraction processes. It has the structure of a reverse banyan network (RBN) and consists of controlled switching elements (CSEs) which is obtained by extending the passive iterative-cells introduced by Narasimha [1994]. The CSE-based RBN has a set of external control inputs (ECIs) in addition to the data input and output lines and can generate different output patterns according to the ECI values. It is shown through four properties that the CSE-based RBN can perform the distribution function of the conventional distributor. In addition, it is rigorously described in the properties how to determine the set of ECI values to achieve the desired distribution function, which includes the distribution in the normal mode, in the reversed mode, and in alternation of these two modes. The proposed CSE-based distributor can be applied to a variety of occasions by modifying the use of the counter, the numbers to write on the registers, and the table to store the ECI values. Some of useful examples are demonstrated through applications to shift-sequence permutation, N×R concentration, nonblocking point-to-point switching, and virtual FIFO queueing     

An optical router with multistage management functions for asynchronous optical packet switching network

An optical router with multistage distributed management features for the asynchronous optical packet switching (OPS) network is presented, which can improve switching capacity and all-optical scalability. A compact recycling-fiber-delay-line (Rec-FDL) based collision resolution mechanism is proposed to resolve the contentions for asynchronous and variable length optical packets. The analysis models of stabilities, packet loss rates (PLR) and average packet waiting latencies (PWL) for the router are developed based on the timer based optical packet assembly algorithm. The simulation shows that PLR and PWL for a 400-byte optical packet transmitted in the 32 wavelengths dense wavelength division multiplexing (DWDM) system equal to 3.48 × 10⁻⁴ and 0.072 ns, respectively. The non-blocking switching can be realized for the packets with lengths less than the buffer granularity of the Rec-FDL, and the optimized performance for the proposed router can be obtained through properly selecting of the system parameters.     

核心通信网的光分组交换

文章首先简单说明了新一代通信网需要使用分级交换的由来。接着详细叙述了光分组交换在未来光通信网的应用，包括节点结构、分组格式、输入、输出接口和一些特别重要的技术，如再生、同步、信头处理、缓冲、空间交换和波长转换等。     

太比特可重构全光交换网络设计

通过使用硅基液晶技术,在高非线性光纤中采用双向简并四波混频,提出了一种可重新配置的太比特网络可重构全光交换模块,实现了对23个100Gb/s差分正交相移键控信道2.3Tb/s的高速率可重构全光交换。当比特误码率为10-9,全光上/下路和光功率均衡的功率代价小于1.5dB,可切换的双通道和同步7通道数据交换功率代价小于5dB。     

Multirate payload switching using a swappable optical carrier suppressed label in a packet-switched DWDM optical network

Optical packets with multirate payloads have been demonstrated for optical label switching (OLS) and transport in a multihop dense wavelength-division-multiplexed (DWDM) optical network with over 200 km fiber and a low-power penalty for the first time. The key functions for label generation, swapping, and switching have been successfully realized.     

Software Defined Networking (SDN) controlled all optical switching networks with multi-dimensional switching architecture

Ultrahigh throughout capacity requirement is challenging the current optical switching nodes with the fast development of data center networks. Pbit/s level all optical switching networks need to be deployed soon, which will cause the high complexity of node architecture. How to control the future network and node equipment together will become a new problem. An enhanced Software Defined Networking (eSDN) control architecture is proposed in the paper, which consists of Provider NOX (P-NOX) and Node NOX (N-NOX). With the cooperation of P-NOX and N-NOX, the flexible control of the entire network can be achieved. All optical switching network testbed has been experimentally demonstrated with efficient control of enhanced Software Defined Networking (eSDN). Pbit/s level all optical switching nodes in the testbed are implemented based on multi-dimensional switching architecture, i.e. multi-level and multi-planar. Due to the space and cost limitation, each optical switching node is only equipped with four input line boxes and four output line boxes respectively. Experimental results are given to verify the performance of our proposed control and switching architecture.     

Robust photonic transport network implementation with optical crossconnect systems

We adopt the optical path concept to develop a photonic transport network. Because robustness is critical in a nationwide backbone network, we implement, as a first step, digital frame-based optical path network systems. NTT has developed several types of photonic transport systems. They are an optical path cross-connect system which has little quality of service monitoring large-scale integration circuit for each wavelength; a photonic transport payload assembler-disassembler, which accommodates client signals into optical path payloads and vice versa; and a repeater. The implementation of a PTS is depicted. A network-element-level operating system and an optical-network-level operating system are required to operate the WDM photonic transport network. We introduce a TMN-based network operating system. Finally, an overview of NTT's photonic transport network trial is presented     

Micromechanical optical switching with voltage control using SOImovable integrated optical waveguides

Optical switching is demonstrated using movable integrated optical waveguides fabricated on silicon-on-insulator substrates. The switching effect is produced by the voltage-controlled micromechanical deflection of the movable waveguides. The dynamic response of the deflection is studied. A contrast ratio of 12 dB of switching is obtained using an applied voltage of less than 10 V. At 20 V, the contrast ratio is about 40 dB     

Electron-beam controlled switching using quartz and polycrystallineZnS

Results of electron-beam controlled switching experiments with switch samples of quartz crystal and polycrystalline zinc selenide (ZnSe) are presented. For switch samples of both materials, drastic reductions of the switch resistance were induced by the electron beam. The quartz sample showed very fast temporal response (less than 1 ns) with potential applicability for current control. The ZnSe samples, on the other hand, showed longer current transients (on the order of 10 ns) with exponential development of the switch resistance after the electron beam pulse     

A novel scheme for generating optical dark return-to-zero pulses and its application in a label switching optical network

We experimentally demonstrate a novel and simple method to generate a dark return-to-zero (RZ) pulse with tunable pulsewidth and extinction ratio by using a dual-arm LiNbO /sub 3/ intensity modulator. Our experimental results show that this dark RZ pulse signal can be used in a 10-Gb/s optical packet switching system as an optical label. In addition, we demonstrate that this dark RZ label can be easily erased using the gain saturation effect in a semiconductor optical amplifier.     

统一交换技术的研究和实现

文章介绍了统一交换原理和实现统一交换的关键技术,包括信元交换技术和 SAR(切割与重组)技术,给出了统一交换设备实现功能框图,讲述了设计中需要关注的交换效率、时延、交换板冗余保护和交换容量计算等方面的问题。该文的成果已经在光传输设备上得到应用,并取得了良好的效果。该技术具有明显的优势,是构成下一代通信网络的关键技术之一。     

一种支持业务均衡的OBS自适应多可达性路由机制

针对光突发交换(OBS)网络中如何高效解决频繁发生的光突发竞争问题,提出了一种支持业务均衡的OBS自适应多可达性路由机制(AMR-LB).首先根据发送端发送业务量大小和当前网络业务承载状态,按需地为光突发确定多可达性路由;然后在非线性规划下,自适应地调整各条路由的业务承载比例.通过性能仿真,并与自适应替代路由算法(AA...     

Cost-saving two-Layer wavelength conversion in optical switching network

A novel two-layer wavelength conversion (TLWC) scheme, for reducing the implementation cost of an optical switching (OS) node, is presented in this paper. The study stems from practical observation that wavelength converters are expensive. The paper thus presents a new OS node architecture that uses significantly less wavelength converters without compromising on drop performance. In this TLWC system, partial wavelength converters (PWCs), which can only convert wavelengths within a limited range, form the first layer; thereafter, complete wavelength converters (CWCs), which can convert wavelengths within all input ranges, form the second layer. When new optical data needs a wavelength converter, PWC resources are first provided; if PWC resources are not available, CWC resources are used. For the case of the CWC layer, a sharing-mode scheme called the share per fiber (SPF) mode for improving the utilization of the limited number of wavelength converters is proposed. Subsequently, a two-dimensional Markov-chain model of TLWC-SPF is presented to evaluate its performance. Numerical-simulation results are presented to verify the accuracy of the analytical model. The analysis shows that the cost of the OS fabric of TLWC-SPF is similar to an OS node employing a limited number of CWCs (i.e., CWC-SPF). However, in terms of wavelength-converter savings, the TLWC-SPF architecture provides 50% (in heavy load) savings compared to full wavelength conversion (FWC) optical nodes, while 40% savings is achieved compared against CWC-SPF nodes.     

Photonic switching modules designed with laser-diode amplifiers

Photonic switching elements are designed from semiconductor optical amplifiers and passive couplers with fiber-to-fiber unity gain and low crosstalk. Designs for a 2×2 and an asymmetric 2×3 element, and several designs for 4×4 elements, are presented. While most amplifier analyses have stressed the importance of ultralow facet reflectivities for high-gain operation, with protection against external reflections with optical isolators, modest facet reflectivities are satisfactory for these elements. It is also shown that substantial amounts of external reflection can be tolerated. The various architectures are compared according to amplifier count, blocking characteristic, broadcast potential, noise power (amplified spontaneous emission), and fault tolerance     

Offset-free combined neural network/switching control for nonlinearservomechanisms with DSP-based implementation

In this paper, we present a combined neural network/switching controller which is shown to provide offset-free regulation and control in the presence of disturbances. The controller is applicable to nonlinear servomechanisms of the type commonly encountered in motion control. In the paper, the properties of the controller are discussed and the implementation of the overall control system using a microcomputer host with a digital signal processor (DSP) accelerator is described. The paper also includes the results of real-time experiments in applying the proposed controller for position control of a nonlinear servomechanism which provides experimental verification of the effectiveness of the proposed method     

Self-routing planar network for guided-wave optical switching systems

An N*N self-routing planar network suitable for fabricating optical space switches on lithium niobate substrate is presented. The network has O(N/sup 2/) cross points, good modularity and expandability. It also has no waveguide crossovers and no differential attenuation between any of the input and output pairs. A self-routing control can be applied to this network, which is indispensable for ATM switching systems.<>