深圳DDN网络的扩容与优化

深圳ＤＤＶ自开通后发展速度惊人,扩容工程面临许多问题。扩容方案确立后,按照网管结构优化、软件版本升级、节点机组网、时钟源、节点分流、传输测试、割接、网络优化等工作进程吩步骤完成,使得网络的结构、层次、布局更加合理,网络整体效能得以充分发挥。     

DDN网在惠州市电信业务中的应用

本文介绍了ＤＤＮ的基本结构和作用，分析了ＤＤＮ设备的几个特点，指出了ＤＤＮ在惠州市电信业务中的几种主要的应用，最后还指出了ＤＤＮ设备使用中存在的问题。     

无线DDN的简介与分析

为推进行业信息化的发展，中国移动为行业客户提供各种移动解决方案。无线DDN就是中国移动利用已有的网络平台，为行业客户提供的机器到机器的无线数据传输业务。本文主要介绍了无线DDN的特点、承载方式以及网络结构，并结合实际介绍无线DDN在行业应用中的典型案例。     

面向机载电子设备的自动化测试系统设计

随着机载电子设备复杂性的不断增长,测试的难度和工作量也在不断加大.为了有效应对测试带来的挑战,国外设备供应商研制了自动化测试系统.基于机载设备测试要求和系统工程方法,梳理了自动化测试系统应满足的测试场景,分析了系统需求,设计了硬件架构和软件架构,并专项设计了自动化测试软件的框架.在某机载型号研制中应用了设计方案,制造了...     

基于AXIe架构的通用测试平台设计

基于ATCA架构的测试测量总线一AxIe（AdvaneedTCAeXtensionsforInstrumentationandTest）专门针对测试领域的需求对ATCA作了必要的扩充,AxIe是推动自动测试系统向标准化、模块化和系列化发展的关键技术。基于AXIe架构的通用测试平台可改变当前通信装备及模块由于通信体制和接口的复杂多样而导致其通用测试平台缺乏的现状,能够为通信装备的设计验证、生产调试、系统联试、出厂验收、培训演练和入网测试等各个环节提供有效的综合测试手段。通过COM—e和FPGA等模块对基于该架构的测试仪器单元进行了实现。     

3G核心网电路域设备性能测试

随着核心网引入软交换,从基于TDM承载的传统电路型交换到基于IP承载的R4软交换架构,设备容量大幅增加,对其设备性能进行全面评估有很大的意义.本文主要论述3G核心网电路域设备性能测试话务模型、测试组网、测试工具、测试内容等,为相关测试提供经验.     

HONET在数据通信中的应用

由于经济条件的限制，我国ＤＤＮ用户节点侧一直发展缓慢，用户使用很不灵活，华为ＨＯＮＥＴ综合业务接入网的开发思路是为满足用户实际需求，除接入公用电话网提供电话，传真等多种业务 外，还可作为ＤＤＮ的接入设备，实现ＤＤＮ的延伸，为用户提供数字数据接入和系统内部的各种速率接口的数据专线业务。     

An OSI-based interoperability architecture for managing hybridnetworks

The management of hybrid corporate networks comprising a wide variety of equipment and services offered by different vendors and service providers is addressed. The public carrier environment in which such networks must operate is described. Five categories of system management functional areas set forth in the ISO/IEC Open Systems Interconnection (OSI) standards are defined. They are fault management, accounting management, configuration management, performance management, and security management. The interoperability architecture provided by the standards is examined, and two example applications are given: a corporate banking voice network, and OSI-based configuration management applied to automatic call distribution     

Choosing the appropriate ISO layer for LAN interconnection

The authors discuss the technical ramifications involved in the choice between interconnecting local area networks with a layer 3 (ISO network layer) versus layer 2 (ISO data link layer) approach, that is, routers versus bridges. They consider the distinction between two layers and define routers and bridges. They then argue the case for each. They conclude that neither approach is better, in the sense that each has its appropriate problem space, and suggest a mixture of relays     

Interoperability Verification in ISO 18000-7 Active RFID Systems: Experimental Setup and Results

Interoperability in an RFID system conforming to ISO 18000-7 standard is defined as the ability of any commercial interrogator to communicate with any commercial tag. A possibility that conformance verification in the physical communication layer between active tags and interrogators (readers) does not satisfy the interoperability property is established. Challenging the traditional or matrix test to verify interoperability, a novel methodology to verify interoperability for active RFID systems in particular and all communication systems following a command-reply protocol in general is introduced in a prior publication. In this article, the methodology is experimentally implemented using industry standard laboratory equipment and automation tools to develop a fully automated interoperability test suite. The automated test system design considerations, challenges and results are discussed in detail. For a particular equipment, the NI-5671 Radio Frequency Signal generator, the maximum number of samples that can be tested for different parameters of the physical communication layers are provided. The equipment limitations are discussed to provide the reader with guidelines to experiment with, and a reference to evaluate the resolution (one measure of the accuracy of the test) of different equipment. The different parameters considered in the test and their interactions in determining the interoperability property are recorded.     

我国公用DDN骨干网

本文介绍了我国公用ＤＤＮ骨干网一期工程的网络结构，基本功能，与其它网的互连以及用户入网方式等技术问题，作者在最后提出了一些建议以供研讨。     

Architecture and design of a portable protocol tester

The architecture and design of a new generation portable protocol tester that includes most of the capabilities of dedicated protocol test systems and all of the capabilities of commercial portable testers are discussed. The general tester environment and model of the system under test as viewed by the protocol tester are presented. A conceptual model of a protocol tester that captures its main functional requirements is proposed, and the basic performance requirement is presented. The design and structure of a protocol tester that provides the functional and performance capabilities described are outlined. The implementation utilizes custom VLSI multiprocessors and a special-purpose multiprocessing operating system to allow active and passive testing of more than one system simultaneously. The testing software on each processor is organized as a single process consisting of protocol and test entities with event occurrences being implemented as procedure calls aided by hardware subprocessors. All testing methodologies defined by the ISO, including the ferry method, can be implemented and standardized conformance test suites supported. Suggestions for future extensions to the design are offered     

安徽电信基于规模DT的主动优化体系研究与实现

提出了一种基于规模DT的主动优化体系,借助社会资源,利用自动测试设备,模拟用户行为进行规模测试,及时、全面地获取网络信息;研究了规模DT的实现方式、平台架构以及测试设备部署模型,并提出基于栅格匹配的智能网优分析模块,直接面对问题,实现网优集约化。通过实例表明,规模DT实现了先于用户发现问题的主动优化体系,以问题解决为导向提升用户感知。     

车辆电气设备的抗扰度性能测试

ISO 7637-2说明了安装在12 V和24 V电源系统上的客车商用车辆上电气设备电瞬变干扰的传导试验方法与步骤,用以保证设备的电磁兼容性.讲述了注入瞬变干扰的型式试验,介绍了改进设备电磁兼容性的常用措施,并对国际标准ISO 7637-2中的5种波形进行了描述.     

OSI Reference Model--The ISO Model of Architecture for Open Systems Interconnection

Considering the urgency of the need for standards which would allow constitution of heterogeneous computer networks, ISO created a new subcommittee for "Open Systems Interconnection" (ISO/ TC97/SC 16) in 1977. The first priority of subcommittee 16 was to develop an architecture for open systems interconnection which could serve as a framework for the definition of standard protocols. As a result of 18 months of studies and discussions, SC16 adopted a layered architecture comprising seven layers (Physical, Data Link, Network, Transport, Session, Presentation, and Application). In July 1979 the specifications of this architecture, established by SC16, were passed under the name of "OSI Reference Model" to Technical Committee 97 "Data Processing" along with recommendations to start officially, on this basis, a set of protocols standardization projects to cover the most urgent needs. These recommendations were adopted by T.C97 at the end of 1979 as the basis for the following development of standards for Open Systems Interconnectlon within ISO. The OSI Reference Model was also recognized by CCITT Rapporteur's Group on "Layered Model for Public Data Network Services." This paper presents the model of architecture for Open Systems Interconnection developed by SC16. Some indications are also given on the initial set of protocols which will-likely be developed in this OSI Reference Model.     

A Parallel Tester Architecture for Accelerometer and Gyroscope MEMS Calibration and Test

This paper describes a tester architecture for Accelerometer and Gyroscope Micro-ElectroMechanical System (MEMS) devices test and calibration, allowing increased parallelism rate and process accuracy. The proposed tester architecture tackles some critical issues related to MEMS testing, such as mitigating mechanical concerns that potentially impact on the equipment Mean Time Between Maintenance and guaranteeing a sufficient number of measurements in the time unit. The proposed strategy consists in an innovative and low cost tester resource partitioning that overcomes current limitations to multisite Accelerometer and Gyroscope MEMS testing. A tester prototype was implemented exploiting FPGAs; feasibility and effectiveness of the proposed methodology was demonstrated on commercial accelerometer and gyroscope MEMS devices.     

Advancing Radio Testing Methodology via Formal Notations

Mandatory verification of the correct operation of equipment in public environments will increase the complexity of test equipment due to the high number of new vendors in the foreseen scenarios. Protocol and radio conformance tests are usually thought to be two separated fields, which makes that the test system design process is different for both cases. However, the only lack of radio test cases is the formalization of tests using a formal test notation. In this paper, it is shown how the design process can be merged for both protocol and radio test systems by modelling radio tests in TTCN. In this case, the same architecture and development tools can be used in the whole testing process, and a reduction of costs and time can be achieved. Abstraction of the instrumentation equipment and standardization of a control interface are required.     

关于规划和建设全国数字数据网的若干问题及建议

数字数据网(DDN)是利用数字信道(光缆或数字微波)及数字交叉连接(DXC)设备来传送数据信号的数据传输网。目前,组建全国性的DDN既有必要性又有可能性。本文针对规划和建设全国性DDN存在的若干问题提出了建议。     

DDN高速数传异常原因分析

DDN节点担负着航天试验任务试验信息、指挥调度及日常通信的数据复接、交换和传输任务。针对某次试验任务中,某节点向指控中心进行高速数据传输时所出现的异常问题,根据当时及事后所做的问题排查及验证工作进行了整理、归纳和分析,得出了初步结果,并提出了解决该问题的相应措施和方法。     

一种基于SDH光网络的DDN实现方案

DDN网络为专线业务的发展做出了较大的贡献,但是,其网络的持续发展却遇到了诸多困难.文中分别论述了DDN网络和SDH网络的发展,充分考虑到SDH(MSTP)光网络的发展现状,综合DDN网络以及DDN业务自身的特点和实际情况.提出一种基于SDH(MSTP)光网络的DDN业务实现方案.该方案实现了高性价比的DDN网络的升级和扩容,解决了DDN网络的发展中遇到的诸多困难,在一定程度上又丰富了MSTP的内容.