双线路为何不能自动切换

分中心采用博达2621路由器，配备了2MSDH和VPN双线路连接区域中心，分中心及区域中心路由器均采用OSPF动态路由协议传播路由。当一条线路故障时，数据包会从另一条线路转发，这样做提高了数据通信的可靠性。但实际工作中遇到了麻烦：某个分中心的SDH 线路中断的时候，数据包的路由并没有切换到VPN隧道上。     

基于GIS的主干光缆路由敷设条件评价研究

利用GIS技术以及ArcGIS等GIS专业软件,结合相关主干光缆路由敷设线路设计理论,以江苏省灌云县城区为试验区,试图提出一套基于GIS的主干光缆路由敷设条件评价方法和流程。首先,总结出影响主干光缆路由敷设线路选择的因子并进行量化;然后,结合利用专家打分法得到的影响因子权重计算出总的作用分值并生成最终评价结果。结果表明：利用GIS空间分析技术能够比较有效地进行主干光缆路由敷设条件评价,其结果可以为主干光缆敷设线路设计等提供参考。     

用于下线间无线序光缆割接的旧路由光缆法

通过测试旧路由光缆,查找出旧路由光缆同机房侧光缆连接的光纤色谱线序信息,用于处理下线间无线序光缆割接难题。实践证明采用旧路由光缆法进行下线间无线序光缆割接可确保割接完毕后光路、线路直接通,两端光纤无需倒换,并且可按重要线路优先原则进行光缆路由变更。此外,旧路由光缆法还可用于处理光缆故障。     

光缆割接常见故障及案例分析

1 引言 在日常光缆线路维护中,光缆路由改迁、光缆线路阻断抢修和光缆线路大修改造等等较为常见, 均需进行更换光缆或对线路进行割接.     

局域网中使用无线路由组网因网段相同产生的联网故障分析及解决方法

随着无线上网本、智能手机等具备WIFI功能的无线终端设备的普及,无线宽带路由得到了广泛的应用,随着无线路由的广泛应用,也出现了各种因无线路由使用或设置不当而造成的各种联网故障。本文分析了一种因无线路由和其接入的局域网网段相同而产生的联网故障,并提出了解决方法。     

银川市区有线电视网络光缆割接规程

由于城市道路改、扩建和光缆杆路、路由的调整，需要对光缆线路进行割接。光缆线路由架空转入地埋管道、将架空光缆线路路由做必要的调整。为了保证光缆割接工作顺利进行，保证业务在最少时间内中断，提高工作效率，必须进行严密的组织配合和协调工作。     

超长距通信技术在电力系统中的应用研究

1.引言超长距无中继通信系统具有端到端直达通路,无任何中继设备和建设,运营维护成本低等特点,对于像我国这样幅员辽阔的地区,可有效解决大城市间搭建长跨距直达路由,提高通信效率;同时,可有效解决通信路由经过沙漠,沼泽,森林等无人区的问题;特别是对于我国目前进行的跨大区,特高压输电线路的通信系统而言,无疑是一个非常好的解决方案。因为,电力通信线路与普通的通信线路不同,电力通信线路路由走向     

长途干线传输波分线路保护系统介绍

提出了波分系统进行多路由保护的方案,介绍了引入光自动保护系统和通路放大子系统实现波分系统线路保护的基本原理以及实际案例,分析和总结了光线路保护系统的应用效果和需注意的问题。     

浅谈城乡接合部直埋光缆线路维护中的几个要点

城乡接合部直埋光缆线路,受城市建设开发的影响,线路沿线施工次数多,路由改迁多,光缆容易受到外力而损坏,同时由于人口流动大,护线宣传难度大.针对以上特点,在城乡接合部直埋光缆线路维护中,要着力做好以下几点: 1 对线路路由,做到“明标”与“暗记”相结合 近年来,在城乡接合部直埋光缆中断事件中,多数是因施工人员不清楚光缆的详细位置导致的.因此,在标记城乡接合部直埋光缆线路路由时,要有别于乡间田野,做到“明标”与“暗记”.     

基于GIS的主干光缆路由敷设线路设计探索

本文以江苏省灌云县城区为试验区,利用GIS技术以及ArcGIS等GIS专业软件,试图提出一种套基于GIS的主干光缆路由敷设线路设计方法。研究结果表明：利用GIS技术能够比较有效地实现自动化的主干光缆路由敷设线路设计。     

An On-Demand Routing Protocol with Backtracking for Mobile Ad Hoc Networks

A mobile ad hoc network (MANET) is characterized by multi-hop wireless links and frequent node mobility. Communication between non-neighboring nodes requires a multi-hop routing protocol to establish a route. But, the route often breaks due to mobility. The source must rediscover a new route for delivering the data packets. This wastes the resources that are limited in MANET. In this paper, a new on-demand routing protocol is proposed, named on-demand routing protocol with backtracking (ORB), for multi-hop mobile ad hoc networks. We use the multiple routes and cache data technique to reduce the rediscovery times and overhead. After executing the route discovery phase, we find out a set of nodes, named checkpoint, which has the multiple routes to the destination. When a checkpoint node receives a data packet, it caches this data packet in its buffer within a specific time period. When a node detects a broken route during the data packets delivery or receives an error packet, it will either recover the broken route or reply the error packet to the source. If a node can not forward the data packet to the next node, it replies an error packet to the source. This packet is backtracking to search a checkpoint to redeliver the data packet to the destination along other alternate routes. The main advantage of ORB is to reduce the flooding search times, maybe just delay and cost while a route has broken. The experimental results show that the proposed scheme can increase the performance of delivery but reduce the overhead efficiently comparing with that of AODV based routing protocols. Hua-Wen Tsai received the B.S. degree in Information Management from Chang Jung Christian University, Taiwan, in June 1998 and the M.B.A. degree in Business and Operations Management from Chang Jung Christian University, Taiwan, in June 2001. Since September 2001, he has been working towards the Ph.D. degree and currently is a doctoral candidate in the Department of Computer Science and Information Engineering, National Cheng Kung University, Taiwan. His research interests include wireless communication, ad hoc networks, and sensor networks. Tzung-Shi Chen received the B.S. degree in Computer Science and Information Engineering from Tamkang University, Taiwan, in June 1989 and the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, in June 1994. He joined the faculty of the Department of Information Management, Chung Jung University, Tainan, Taiwan, as an Associate Professor in June 1996. Since November 2002, he has become a Full Professor at the Department of Information Management, Chung Jung University, Tainan, Taiwan. He was a visiting scholar at the Department of Computer Science, University of Illinois at Urbana-Champaign, USA, from June to September 2001. He was the chairman of the Department of Information Management at Chung Jung University from August 2000 to July 2003. Since August 2004, he has become a Full Professor at the Department of Information and Learning Technology, National University of Tainan, Tainan, Taiwan. Currently, he is the chairman of the Department of Information and Learning Technology, National University of Tainan. He co-received the best paper award of 2001 IEEE ICOIN-15. His current research interests include mobile computing and wireless networks, mobile learning, data mining, and pervasive computing. Dr. Chen is a member of the IEEE Computer Society. Chih-Ping Chu received the B.S. degree in agricultural chemistry from National Chung Hsing University, Taiwan, the M.S. degree in computer science from the University of California, Riverside, and the Ph.D. degree in computer science from Louisiana State University. He is currently a Professor in the Department of Computer Science and Information Engineering of National Cheng Kung University, Taiwan. His current research interests include parallel computing, parallel processing, component-based software development, and internet computing.     

从科学传播理论的角度谈台湾的科普困境

本文所谈的科学传播是指将科学信息(自然科学和工程技术的知识、观念等资讯)传播得正确、广泛、深入、快速且有效,实现科学普及、民智发达的境界。论述前提限于大众传媒的科普范畴,至于正规学校教育中的自然科学教育则不在讨论之列。本文从科学与媒介、科学作者、科学写作、科学消息之传播,以及科学家等5个理论研究的面向来分析台湾的科普困境,以为台湾的科普是相当值得探究的课题。     

通信网节点间路由及可靠性指标全代数化算法

为了精确地计算通信网可靠性指标，需采用布尔代数算法，路由寻找是该算法必须要解决的关键问题。研究出一种新的路由算法，按照逻辑代数运算规则，采用关联矩阵变换方式计算，适合计算各种拓扑形式的通信网络两节点间的全部可能路由，且不会出现闭环路由现象，完全符合通信传输规则。基于该路由算法，叉解决了端到端通信网可靠性指标全代数化计算问题，且可靠性指标是综合了通信链路和节点两方面的因素而定义的，从而弥补了以往可靠性计算只注重链路失效而忽视节点失效的不足。通过算例详细地说明各算法的计算过程．并验证了算法的正确性。     

大规模输电线路状态监测传感器网络的周期性低功耗通信技术方案

为了实现输电线路监测的功耗低、寿命长、绿色发展的目的，提出大规模输电线路状态监测传感器网络周期性低功耗通信技术方案。依据网络中传感器网络组网特征以及节点运行状态转换特点，设置睡眠定时器，以周期性运行方式使传感器网络通信节点在初始化、睡眠、激活状态间转换，通信节点在输电线路状态监测数据无传递需求时进入睡眠状态，节省通信功耗；传感器网络汇聚（sink）节点利用梯度创建上行路由，通过源路由的方式创建下行路由，以跳数和剩余能量为依据进行上、下行路由数据分组传递，降低节点功耗，延长通信运行时间。实验显示，大规模输电线路状态监测传感器网络应用该技术方案后，通信功耗明显降低，运行时间明显延长，且不会影响监测传感器网络的数据传输性能，延长了监测传感器网络的使用寿命。     

基于uIP的通信路由控制器的设计

系统采用ARMCortex-M3为内核的32位微控制器LM3S6965,利用其内置以太网控制器,成功移植了uIP协议栈,并在该协议栈上实现一个可手动选择通信路由和实时显示各通信端口状态的嵌入式通信路由控制器。介绍了嵌入式通信路由控制器设计的硬件需求和软件开发过程,涉及以太网控制器物理接口的硬件设计,uIP协议栈的总体架构,uIP协议栈数据包处理流程,LM3S6965内置以太网控制器驱动程序以及路由控制程序的编写。为嵌入式网络通信提供了一个切实可行的解决方案。     

中国台湾电信市场现状

台湾电信市场的开放大致分四个阶段,从1995年起,陆续开放了移动通信、卫星通信及固定通信等多种业务。固网市场,2001年新世纪资通、台湾固网和力霸宽频电信的加入打破了中华电信的独家垄断,开始形成四强竞争的新局面。移动领域,1997年底6家运营商8张民营执照的发放开始了该领域史无前例的竞争。在2001年1月,台湾大哥大、远致电信、亚太行动宽频、联邦电信和中华电信获得了3G执照,累计竞标金额达488.99亿元(新台币)。     

An Improved GGSN Failure Restoration Mechanism for UMTS

Universal mobile telecommunications system (UMTS) provides packet-switched data services for mobile users. To efficiently deliver packets in the UMTS core network, the PDP contexts (i.e., the routing information) are maintained in the volatile storage (e.g., memory) of SGSN, GGSN, and UE. The GGSN routes packets between the UMTS core network and external data networks, and thus has heavy traffic and computation loading, which may result in PDP contexts lost or corrupted, and the QoS of the UMTS network may degrade significantly. To resolve this issue, 3GPP 23.007 proposes a mechanism for GGSN failure restoration. In this mechanism, the corrupted PDP contexts can be restored through the PDP Context Activation procedure. However, this incurs extra signaling cost to the network. To reduce the network signaling cost and delay for restoration of the corrupted PDP contexts, this paper proposes an improved mechanism “GGSN Failure Restoration” (GFR) with different backup algorithms. The analytic models and simulation experiments are conducted to evaluate GFR.Our study indicates that the GFR mechanism can significantly reduce the cost for the PDP context restoration. Phone Lin (M'02) received his BSCSIE degree and Ph.D. degree from National Chiao Tung University, Taiwan, R.O.C. in 1996 and 2001, respectively. From August 2001 to July 2004, he was an Assistant Professor in Department of Computer Science and Information Engineering (CSIE), National Taiwan University, R.O.C. Since August 2004, he has been an Associate Professor in Department of Computer Science and Information Engineering (CSIE), National Taiwan University, R.O.C. His current research interests include personal communications services, wireless Internet, and performance modeling. Dr. Lin is a Guest Editor for IEEE Wireless Communications special issue on Mobility and Resource Management. He is also an Associate Editorial Member for the WCMC Journal. Guan-Hua Tu received his B.S.C.S.I.E degree from National Central University, Taiwan, R.O.C., in 2001 and his Master degree in Computer Science from National Taiwan University, Taiwan, R.O.C., in 2003. He is currently a software engineer in MediaTek Inc. His resarch interests include personal communication services, mobile computing, and performance modeling.     

Design of optimum criterion for opportunistic multi-hop routing in cognitive radio networks

The instability of operational channels on cognitive radio networks (CRNs), which is due to the stochastic behavior of primary users (PUs), has increased the complexity of the design of the optimal routing criterion (ORC) in CRNs. The exploitation of available opportunities in CRNs, such as the channel diversity, as well as alternative routes provided by the intermediate nodes belonging to routes (internal backup routes) in the route-cost (or weight) determination, complicate the ORC design. In this paper, to cover the channel diversity, the CRN is modeled as a multigraph in which the weight of each edge is determined according to the behavior of PU senders and the protection of PU receivers. Then, an ORC for CRNs, which is referred to as the stability probability of communication between the source node and the destination node (SPC_SD), is proposed. SPC_SD, which is based on the obtained model, internal backup routes, and probability theory, calculates the precise probability of communication stability between the source and destination. The performance evaluation is conducted using simulations, and the results show that the end-to-end performance improved significantly.     

Comparison of the design of a contoured-beam and an elliptical-beamsatellite offset reflector antennas to cover the Taiwan island regionfor satellite communications

For the design of the satellite antenna for the future geostationary (GEO) satellite communication or DBS (direct broadcasting satellite) applications to serve the Taiwan Island region, it may be required to have a antenna beam which effectively covers the Taiwan region and reduces the antenna radiation level in the nearby area of mainland China. Two cases of the Ka-band (20 GHz) satellite antenna, a shaped offset reflector antenna to synthesize a contoured beam and an elliptical offset reflector antenna to generate an elliptical beam, have been studied. This paper presents the comparison and discussion of the antenna coverage performance of the two designs     

Generating routes for autonomous driving in vehicle-to-infrastructure communications

The study of vehicular networks has attracted considerable interest in academia and the industry. In the broad area, connected vehicles and autonomous driving are technologies based on wireless data communication between vehicles or between vehicles and infrastructures. A Vehicle-to-Infrastructure (V2I) system consists of communications and computing over vehicles and related infrastructures. In such a system, wireless sensors are installed in some selected points along roads or driving areas. In autonomous driving, it is crucial for a vehicle to figure out the ideal routes by the communications between its equipped sensors and infrastructures then the vehicle is automatically moving along the routes. In this paper, we propose a Bezier curve based recursive algorithm, which effectively creates routes for vehicles through the communication between the On-Board Unit (OBU) and the Road-Side Units (RSUs). In addition, this approach generates a very low overhead. We conduct simulations to test the proposed algorithm in various situations. The experiment results demonstrate that our algorithm creates almost ideal routes.