有线电视网络改造的新模式——FTTB＋1550nm

随着有线网络数字化的逐步深入，为满足业务的需求，各地又掀起了光传输网络改造的热潮。在改造的过程中，各地网络公司根据本地网络实际情况不同，采用了不同的网络改造模式，那么到底下一步光网络改造的方向是什么？改造的着眼点又在哪里？笔者根据近期在网络改造实践中遇到并解决的问题，得出了一些比较清晰的观点，现在总结出来，供同行们共同讨论。     

网络双向化改造若干问题探讨

网络双向改造中的接入网改造普遍选用EPON＋LAN／EOC方式，但是在EPON＋LAN／EOC改造过程中，有很多实际问题需要探讨交流，只有吸收借鉴各地网络改造的经验教训，才能促进网络良性发展。     

三网融合形式下广电网络双向改造技术

随着三网融合不断的推进，广电面临着对有线电视双向网络升级改造的重要任务。也就是把先前的HFC单向网络改造成为双向网络，在改造过程中使用哪种接入技术，广电网络公司需要对整体的双向网络改造结构摸索出一条适合自己的道路。     

项目管理在HFC网络改造中的应用

从实践的角度介绍项目管理在网络改造中的指导作用,用项目管理计划、组织、控制和评价的方法来分析HFC网络改造工作,探讨有线电视网络改造的有效方法。     

接入网改造中无源光网络技术的分析与应用

接入网改造是“十四五”时期我国网络基础设施升级和改进的基本内容。在当前持续推进的接入网改造中,无源光网络技术的应用愈发普遍,利用该技术对提升接入网的改造效果意义重大。基于此,在概括介绍无源光网络技术的基础上,分析研究无源光网络技术在接入网改造中的应用方式和应用产生的效果,以期为接入网改造中无源光网络技术的有效应用提供相关参考。     

HFC网络实现多功能业务接入的改造方案(下)

3.2.3 HFC网络光节点的划分及接入设备的选择 光节点的大小,在不同地区HFC网络建设时,就已确定.对原来网络进行双向改造时,提出将光节点改小或要求光节点按星型等距离范围分布都将给网络的改造带来不方便.最重要的是抛弃"必须全面双向改造到户"的概念,要采用适合的接入设备,采用综合改造的方法,在原有网络的基础上实现增值.要以改造快捷、经济及可靠为原则.当然,在条件成熟时,应对光节点加以改造.     

浅谈海门市1550nm网改思路

本文介绍了海门市1550nm网络改造的具体思路。通过分析网络改造的背景及网络现状，提出了适用于海门市网络改造的规划设计。并阐述了网络改造的相关想法及设备选型方法。     

HFC网络实现多功能业务接入的改造方案

3.2.3 HFC网络光节点的划分及接入设备的选择 光节点的大小,在不同地区HFC网络建设时,就已确定。对原来网络进行双向改造时,提出将光节点改小或要求光节点按星型等距离范围分布都将给网络的改造带来不方便。最重要的是抛弃“必须全面双向改造到户”的概念,要采用适合的接入设备,采用综合改造的方法,在原有网络的基础上实现增值。要以改造快捷、经济及可靠为原则。当然,在条件成熟时,应对光节点加以改造。     

海门城区有线电视EPON网络规划设计方案

随着三网融合时代的到来,有线电视从模拟向数字全面转换,对有线电视网络进行双向化改造也变得更加迫切。EPON方案作为一个无源光网络非常适合广电网络的双向化改造,该方案在技术上有前瞻性,在网络功能上有扩展性,介绍海门城区有线电视双向网络改造思路和规划方案,为双向化网络改造提供参考。     

有线电视光纤到户网络改造方案的策略研究

各地广电积极开展有线电视光纤到户网络改造方案,进行网络建设,本文就有线电视光纤到户网络改造相关技术进行分析,对有线电视的光纤到户网络改造提出有效方案,希望有助于有线电视改造升级.     

Alternative Schemes for Dynamic Secure VPN Deployment in UMTS

Three alternative schemes for secure Virtual Private Network (VPN) deployment over the Universal Mobile Telecommunication System (UMTS) are proposed and analyzed. The proposed schemes enable a mobile node to voluntarily establish an IPsec-based secure channel to a private network. The alternative schemes differ in the location where the IPsec functionality is placed within the UMTS network architecture (mobile node, access network, and UMTS network border), depending on the employed security model, and whether data in transit are ever in clear-text, or available to be tapped by outsiders. The provided levels of privacy in the deployed VPN schemes, as well as the employed authentication models are examined. An analysis in terms of cost, complexity, and performance overhead that each method imposes to the underlying network architecture, as well as to the mobile devices is presented. The level of system reliability and scalability in granting security services is presented. The VPN management, usability, and trusted relations, as well as their behavior when a mobile user moves are analyzed. The use of special applications that require access to encapsulated data traffic is explored. Finally, an overall comparison of the proposed schemes from the security and operation point of view summarizes their relative performance. Christos Xenakis received his B.Sc. degree in computer science in 1993 and his M.Sc. degree in telecommunication and computer networks in 1996, both from the Department of Informatics and Telecommunications, University of Athens, Greece. In 2004 he received his Ph.D. from the University of Athens (Department of Informatics and Telecommunications). From 1998–2000 was with the Greek telecoms system development firm Teletel S.A., where was involved in the design and development of advanced telecommunications subsystems for ISDN, ATM, GSM, and GPRS. Since 1996 he has been a member of the Communication Networks Laboratory of the University of Athens. He has participated in numerous projects realized in the context of EU Programs (ACTS, ESPRIT, IST). His research interests are in the field of mobile/wireless networks, security and distributed network management. He is the author of over 15 papers in the above areas. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of Electrical Engineering and Computer Science at the University of Connecticut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, MA. During the period 1993–1994 he served as Director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies & Services (ACTS) and Information Society Technologies (IST) programmes funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE). He is chairman of the board of the Greek Universities Network, the Greek Schools Network, and member of the board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

企业VPN技术应用实施浅析

随着企业规模逐渐扩大,远程用户、分支机构、合作伙伴也在不断增多,关键业务的需求增加,出现了一种通过公共网络（如Internet）来建立自己的专用网络的技术,这种技术就是虚拟专用网（简称VPN）。本文首先介绍了VPN的概念,对VPN的实现技术进行了分类和适用性分析,然后分析了各种类型的企业在信息安全方面的需求和限制,根据不同企业的特点提出了不同的VPN解决方案,最后,对VPN在集成电路企业中的应用做了简单的拓朴展示。     

接入控制器安全网络管理系统的设计与实现

在讨论了接入控制器(AC)网络管理系统安全重要性的基础上,分析了SNMP协议的应用,包括对其3个版本SNMPv1、SNMPv2及SNMPv3的优缺点的对比,并解释了该设备网络管理系统采用SNMPv3版本的原因.详细介绍了AC所实现的管理信息库的内容,包括RFC1213协议、IEEE 802.1x协议、RMON协议、Web DHCP、EAP_OTP、EAP_MD5、EAP_TLS、EAP_SIM等多种认证协议以及网络管理系统的五大功能.最后阐述了AC安全网络管理系统结构的设计与实现.     

SOI Technologies Overview for Low-Power Low-Voltage Radio-Frequency Applications

Thanks to their structure, the SOI technologies present several intrinsic advantages for analog and RF applications. Indeed, as it is well established now, these technologies allow the reduction of the power consumption at a given operating frequency. Moreover, the high-insulating properties of SOI substrates, in particular when high resistivity substrate is used, make that these technologies are perfect candidates for mixed-signal applications. In the present paper, we will discuss the performances of the SOI technologies in radio-frequency range. First of all, the high-frequency behavior of SOI substrates, thanks to the characterization of transmission lines, will be shown. The impact of the SOI substrate resistivity on the performances of passive components will also be analyzed. Then, an overview of RF performances of SOI MOSFETs for two different architectures, fully- and partially-depleted, will be achieved and compared to the bulk ones. Finally, the influence of some specific parasitic effects, such as the kink effect, the self-heating effect and the kink-related excess noise, on the RF performances of SOI devices will be studied, thanks to a specific high-frequency characterization.     

自动测试系统中的总线技术

自动测试系统满足现代科研生产中对测试高速度和高精度的要求,其发展方向是标准化、模块化和系列化,而标准的总线技术是满足这三化的关键技术,总线技术作为自动测试系统的核心,其发展推动了自动测试系统的更新换代.按照自动测试系统中出现的总线技术的顺序,依次对GPIB,VXI,PXI,LXI的基本特性、优缺点及应用进行概括,重点是结合在实际中组建自动测试系统对总线的选型,从宏观上比较了选取传统的卡式仪器总线或基于以太网的新型总线的因素.从而使用户在选取总线时更有针对性和目的性.     

雷达探鸟技术发展与应用综述

探鸟雷达已成为机场鸟击防范、风力发电场鸟击风险评估、鸟类自然保护区鸟情观测与科学研究的重要工具。文中首先论述了探鸟雷达的主要组成部分。然后,分析了地面杂波、空域杂波和其他无关目标对探鸟雷达探测效果的影响,进而介绍了传统的杂波抑制方法和相参雷达杂波抑制技术,以及先进的探鸟雷达采用的目标检测、目标跟踪、目标显示、数据记录和雷达组网等数据处理技术。接着,给出了当前的探鸟雷达能够获取的目标轨迹、回波大小、回波强度、信号波动、飞行速度、飞行高度等反映飞鸟目标特性的主要指标。最后,描述了国内外四种典型雷达探鸟系统,并针对雷达探鸟技术的未来发展提出了一些思考及可行性建议。     

事件科普营销模式探究

从事件的视角看科普,已形成了社会公共事件、社会热点事件、社会突发事件等社会事件中嵌入科普的应急科普模式。但从科普的视角看事件,应急科普模式只是依托事件展开科普的组成部分,结合事件营销和科普营销的已有研究基础,本文提出事件科普营销模式,界定其依借公益性、聚焦性和危机性事件的内涵和依附性、新闻性、策划性三个特征,并从科学技术渗透疆常生活、资源整合、投入产出效率等角度论述其兴起的内在依据,并提出借势方式和造势方式下的四种路径。     

CPLD在雷达发射机控制检测单元中的应用

随着雷达发射机技术的不断发展,越来越多的新技术应用于发射机设计中。复杂可编程逻辑器件CPLD和现场可编程门阵列FPGA,同以往的PAL和GAL器件相比,这些器件含有数量众多的可编程逻辑宏单元或逻辑块,规模大,组合能力强,设计成功能各异的逻辑电路,适合于时序、组合等逻辑电路。本文用CPLD对发射机控制功能进行综合处理,控制命令产生部分根据信号处理机通过串行链发来的控制命令产生控制命令,然后对发射机进行相应的控制,并对相关命令根据时序和故障情况进行逻辑链锁,达到最终控制发射机的目的。     

基于高斯分布的基站天线最佳方向角定位算法

为提高天馈问题被发现的准确性和维护效率,提出了基于高斯分布的最佳方向角解决方案来诊断运营商天馈覆盖问题。首先计算 UE 上报的具有定位信息的每个 MR 采样点与基站之间的位置方向信息,然后按照位置方向的一定角度间隔逐个统计各区间的MR采样点占比,取MR采样点占比最大的角度区间为该扇区的、基于用户热点分布的最佳天线方向角,最后将该最佳方向角与后台天线基础数据库中基站方向角进行比对,发现天馈系统接反、天线覆盖方向不合理、后台天线数据库错误等一系列天馈相关问题。经验证,采用该算法发现天馈问题的成本、准确率和效率较现有方法有明显改善?。     

交换超立方体的拓扑性质与嵌入问题研究

 交换超立方体(Exchanged hypercube)作为超立方体的一种变型网络,降低了网络规模增大时所需要的拓扑连接的开销.本文根据交换超立方体的图形化定义,得到交换超立方体的公式化定义,证明了交换超立方部分子网与超立方网同构,提出EHS(s,t)和EHT(s,t)的概念,并在此概念的基础上证明了交换超立方体中只存在长度不小于4的偶数圈,证明了交换超立方体的顶点连通度和边连通度都为min{s+1,t+1}.为使交换超立方体具有更广阔的应用范围,本文还提出了超立方体在交换立方网中的三种嵌入策略,证明了n=s+t+1时,n-1维超立方体Q_n-1能够同胚地嵌入到交换超立方体EH(s,t)中.