HFC混合光纤同轴网组网技术分析

主要介绍了混合光纤同轴网的组成及工作原理,分析了星型网、树形网、星树形网、双星形网和环形网各自的特点,并给出了一设计实例。     

HFC网回传通道中的调制技术

由于ＨＦＣ网采用了树形 －分支型结构，使来自用户端和电缆网的噪声汇聚，形成了回传通道中的噪声漏斗效应，需彩多址复用的调制方式。     

从有线电视网到宽带接入网

目前有线电视网正向星－树形结构的光纤同轴混合网发展，以此为基础建设宽带用户接入网成为人们关注的一个课题，本文介绍了目前有线电视网的发展状况，并对它在向宽带接入网过渡中的关键技术和发展策略进行了讨论。     

关于树形光缆网络光功率分配的计算方法

近几年,我市的有线电视事业发展很快,信号的传输方式由原单一的同轴电缆传输向HFC网(光缆与同轴电缆混合网)转变,为下一步有线电视向图像、语言和数据于一体的多功能综合应用网发展打下了基础。1.光缆传输系统的网络结构光缆传输系统的网络结构可分为星形网、树形网,星——树结合形网和环形网。根据实际情况,我市的光缆网络多为星形和树形结     

一种新型的用户网—“用微波网用户实现三网合一”的初探

在介绍这种新型的用户网之前,先看看目前的几种用户网：（１）同轴电缆网（与光缆的混合网常被称为ＨＦＣ网）;（２）ＭＭＤＳ网,属于点对多点的单向网;（３）光纤用户网,这就是目前被炒得很热的光纤用户的ＦＴＴＨ网。这三种网是不是我们实现信息高速公路的最终途径？下面看看它们的特点。１　ＨＦＣ网１．１　优点（１）频带宽（５～７５０ＭＨｚ或１０００ＭＨｚ）;（２）属于分配网中最经济或最廉价的网络。因为它具有以上两个非常吸引人的优点,所以目前广电部门在研究是否能发展成为Ｂ－ＩＳＤＮ（宽带综合业务数字网）,从而实…     

广州电视台"七网合一"工程项目的实施

介绍了广州电视台"七网合一"互联互通视音频一体化工程项目的建设与应用情况,通过项目的实施,将广州电视台的媒资网、新闻制作网、节目制作网、硬盘播出网、卫星收录网、广告制播网、综合信息网连接成一个集节目资料采集、编辑、制作、存储、检索、浏览、下载、播出、共享为一体的节目交换和信息共享的网络平台,实现各业务系统之间的数据沟通,有效消除"信息孤岛",达到全台网络的整体融合,形成了无带化节目生产流程和无纸化办公流程.     

大城市的传送网结构研究——在多个长途局的城市建设长途中继网面临的问题

为适应大城市出现多个长途局的电信发展需要,已决定在四个城市建设“长途中继网”。通过分析业务网对传送网的需求,讨论了大城市传送网结构。结论是需要把所谓“长途中继网”分成两个独立的部分来建设,一个是属于省际干线网平面的干线子网;另一个是属于中继网平面的第二中继网(第一中继网是原中继网)。两个中继网需要统一规划、建设、管理和运行。在技术上合理的发展方向是建设统一的中继网。     

浅议自愈网技术原理及应用

本主要针对线路保护倒换自愈网、ADM环型自愈网和DXC网状自愈网等三种自愈网的结构、技术原理及应用。进行一些分析与总结。     

HFC回传信道测试结果浅析

HFC网同轴电缆部分的树形结构决定了其工作方式属于共享信道方式,这种方式提供了一个非常有效的传输下行信号的手段。HFC网下行信道具有很宽的传输带宽,可以传输多路模拟电视信号,数字电视信号和其他数据、电话等信号,而且具有良好的信道质量高。但HFC网的上行信道频带很窄,只占用5～42MHz或5～65MHz频段,上行频段正好处于各种干扰与噪声的多发“地带”并且由于上行信道是多点到一点的结构,各处的干扰与噪声都会向前端汇集,这使本来就很脆弱的上行信道面临更加严峻的考验。由于干扰与噪声的性质将决定调制方式及多点接入等HFC网双向…     

关于我省169网与163网统一接入平台方案的探讨

根据目前169、163网共存的技术体制和两网的共同特点,为合理地利用资源,设备的利用率和网络接通率,本文提出了169、163网统一接入平台的方案,旨在对我省的169、163网扩容工程有所帮助。     

Wireless relay networks

Two network architectures for connecting fixed wireless nodes to a central concentrator-relay and star-are combined into a structured network architecture called a relay star network. A relay star network is characterized by the property that there is a unique communication path between any two nodes; that is, the graph of the network is a rooted tree. In this article we present a tutorial discussion of relay star networks using examples and an extended discussion of a protocol for wireless data collection on relay star networks. The target application for this work is data collection on networks of fixed low-cost, low-data-rate environmental monitors such as urban terminals (parking meters, pay telephones, fire alarm boxes, distress call stations, etc.) and utility meters (water, electricity, gas, steam, etc.)     

采用树状星型拓朴结构切实提高骨干网络安全性能

本文介绍了潍坊市国税局根据全市实际情况，在全市国税系统广域网骨干网络改造建设中，将星型拓扑结构改造成树状星型结构，不仅满足了当前和今后一个时期的工作需要，而且还切实提高了广域网骨干网络的安全性能，经过几年的应用实践，证明这种改造是非常成功的。     

一种低轨卫星网络的概率风险评估方法研究

可靠性分析是卫星星座设计过程中不可或缺的一环。针对低轨卫星网络的高可靠性要求,利用概率风险评估的分析方法,结合网络风险及故障树理论,提出了卫星故障树杠铃风险模型。在此模型基础上分析＂铱＂星系统网络,利用卫星工具箱获取每颗卫星对地覆盖人口数,以此为参数计算得到对网络影响较大的节点和链路,对于今后评估卫星网络风险具有一定的启发意义。     

基于OPNET的局域网拓扑建模仿真

为分析比较局域网中星形,环形和树形3种典型的点到点拓扑的优缺点,运用优化网络工程工具(Optimized Network Engineering Tools,简称OPNET)建立3种拓扑模型,并对其性能仿真.通过分析仿真数据,对3种拓扑的延时,通信量和负载进行比较,给出了3种拓扑各自优缺点,从而为网络规划选择的最佳拓扑提供了技术参考.     

The Rainbow-II gigabit optical network

This paper describes the Rainbow-II optical metropolitan area network (MAN), which supports 32 nodes each at 1 Gbit/s over a distance of 10-20 km. Rainbow-II uses optical wavelength-division multiplexing (WDM), in a broadcast star architecture. Each node uses a separate fixed wavelength for transmitting data and a tunable receiver for receiving one of several data streams. The network is implemented in the form of optical network nodes, each attached to a host computer via the high-performance parallel interface (HIPPI). Each network node contains protocol processing hardware to offload the protocol processing work from the host computer onto the node. The goal is to provide full gigabit-per-second bandwidth to end-user supercomputer applications. Preliminary protocol performance measurements in a testbed network are given     

Effects of Long-Term Clock Instability on Master-Slave Networks

Two types of master-slave networks are investigated: oneway and two-way master-slave networks. The one-way master-slave System is a generalization of the well-known hierarchical master-slave tree system. The two-way master-slave system is a novel concept. Sufficient stability conditions are given for both network types. After synchronization is achieved, the frequency drift rate of all oscillators in the network approaches the frequency drift rate of the master oscillator. The steady-state frequency differences between the oscillators and their variances are computed for six network configurations of practical interest. A performance comparison for different network connectivities shows that the two-way master-slave system with a star configuration has the best performance.     

一种基于BP网络的星图识别算法

为了提高星图识别算法的抗噪性能,提出一种基于逆向传播(Back Propagation,BP)网络的识别算法。该算法通过将星图转换成“0”、“1”和“2”的网格矩阵,提取行列数值和星数形成匹配向量,利用多个BP识别子网进行训练完成匹配识别。通过仿真试验得出以下结论:对星等位置和星等添加噪声,当位置噪声标准偏差为2像素时,BP网络算法的识别率和识别时间相对传统栅格算法分别提高2%和60ms,对噪声有较强抗干扰能力,表明BP网络算法具有更快的识别速度。     

Distributed optical passive star couplers

A technique is presented by which a single centralized passive star coupler in an optical star network is replaced by a distributed one. This is done by partitioning the star coupler into numerous pieces and placing them at the network nodes. Such a placement results in a great saving in the number of fibers required to build the star network. In addition to this saving, the problems associated with constructing a large single N*N star coupler are bypassed.<>     

星型光纤传输网络组分结构的研究

对星型光纤传输网络及其组分结构作了分析与研究，得到并组式星型光纤网与单元式星型光纤网光链路损耗间的代数关系，给出了各光分路器分光比的计算方法和公式。     

The modified star-ring architecture for high-capacity subcarriermultiplexed passive optical networks

A modified star-ring architecture (MSRA) consisting of a star network on the upper level and many concatenated ring subnets on the lower level is proposed for subcarrier multiplexed passive optical network (SCM-PON). The upper level star network ensures high network capacity and its weakness in reliability is overcome by the concatenated ring subnets with self-healing capabilities. The self-healing function can be performed at remote nodes (RNs) by using optical switches (OS) to reconfigure the ring subnets if any link fails. Moreover, we design the cascade add/drop transceiver (CAT) structure in the lower level ring subnets to completely eliminate the optical beat interference (OBI) problem and achieve an OBI-free optical network. Finally, we set up an experimental network to demonstrate the feasibility of this cost-effective survivable structure