先进的数字用户线（DSL）技术

该文就接入网技术热点之一--DSL技术进行了介绍，并对DSL的分类，及最常和的ADSL技术，在DSL上开展帧中继，IP与DSL业务的联系等技术作了详细的阐述。     

2001年全球DSL发展回顾

DSL作为一种大众化的宽带接入技术,已在所有发达国家和大多数发展中国家得到推广应用。到2001年第二季度,亚太的用户数首次超过北美,成为世界上最大的市场。一般来说,住宅用户的比例高于商业用户;在DSL发展较快的地区,住宅用户比例更高些;而在DSL发展较慢的地区,商业用户较多。目前各国普遍采用的推广措施主要包括:建立专门的宽带门户网站、与ISP捆绑接入、为一定服务期限的用户打折、为现有的电话用户打折、免费提供支持DSL的计算机,以及提供家用网络业务等。     

承载多业务的DSL网络

本文系统地介绍了DSL网络的现状和宽带业务的需求,并回顾了DSLAM设备和网络形态的演化等,着重阐述了DSL的网络架构为了适应新的业务需求和网络技术演进的趋势,将从ATM汇聚向以太网汇聚转变,并介绍了新的DSL网络架构下VLAN、QoS、组播等关键技术的应用.     

DSLAM技术及发展

在DSL技术应用初期，DSLAM的功能可以认为是一个DSL Modem池，而在DSL技术得到越来越广泛应用的今天，随着业务的不断发展，早期那种简单的DSLAM已越来越不能满足运营商扩展业务、降低运营成本的需求，因此今天的DSLAM已经发展成为支持多种DSL技术、具有强大功能的综合性设备。本从DSLAM的发展历程出发，介绍了DSLAM的形态、国内外的标准化情况、存在的问题以及未来的发展方向。     

ADSL宽带测试技术

介绍国内外数字用户线DSL业务现状、发展趋势、宽带测试需求分忻以及ADSL宽带测试技术，测试项目、组网技术等。     

DSL技术及其在宽带设备中的应用

数字用户线(DSL)技术是国内宽带接入的主流技术,DSLAM(DSL接入复用器)是目前广泛使用的局端宽带接入设备。文中从传输速率、传输距离等方面介绍了ADSL(非对称用户线)、SHD-SL(单线对高速数字用户线)、VDSL(甚高速数字用户线)等多种DSL技术特性,讨论了DSLAM与DSL的复合技术,提出基于SHDSL技术的高速对称数据传输方案将成为IP-DSLAM系统的发展方向。还对基于SHDSL技术的IP-DSLAM网络结构、工作原理进行了阐述。     

企业级DSL设计

数字用户线(DSL)一直是深受居民用户欢迎的接入手段。直到最近，才将它推向企业级用户，以适应这一市场的特有需要。DSL可为各种业务提供多种可选择的低成本传输方案,适合于通信计算机不断增加以及覆盖区内有多个分支机构等情况。企业级的用户,除接入不同服务等级Internet或局域网外,还需要如下服务:多种服务质量(QoS)能力，先进的防火墙,虚拟专用网络，办公室之间的电话呼叫系统语音服务,电视会议和视频点播以及一体化长途质量话音。另外,新颁布的DSL标准,要求制造商按柔性产品体系结构进行设计,使客户能根据各自的需要或随着技术的不…     

美国线路共享政策的实施与现状

线路共享指的是，用户除了从自己归属的本地电话公司（ILEC）以外还能选择从其它运营公司（主要指CLEC）为自己提供数据业务，并且不必安装第二条电话线。线路共享为现有电话线路上开展数据业务竞争铺平了道路，它在美国被视作能否成功开放DSL市场的关键因素。本文对美国针对DSL发展问题出台线路共享政策以及线路共享政策出台后的实施状况加以报道。对于我国制定线路共享政策和实施管理提供参考。     

xDSL断想

随着因特网发展神速，传统拨号上网仍是最广泛的采用手段，但传输速度，即使是ISDN也无法达到要求．因而DSL的发展受到人们注目，成为发展热点。据最近报道，ADSL标准已接批准，IBM日前也宣布了ADSL服务，HDSL，正走向成熟。本文对各种DSL作了介绍。但只代表一种观点。     

多元化的DSL技术与方案

面对数字用户线(DSL)宽带接入业务的大规模投入,如何利用现有资源优化目前的网络,降低运维成本,同时提供更加丰富的业务,成为目前运营商广泛关注的问题.西门子除了拥有领先的ADSLoverISDN/POTS解决方案外,对xDSL接入技术和整体网络解决方案也有最新的见解.     

亚太地区紧跟宽带建设大潮

国际金融危机爆发之后,宽带建设成为全世界的热点,还出现了国家宽带网（NBN）这样的“时髦”词。不仅在北美与西欧,亚太地区也毫不示弱,同样紧跟气势磅礴的宽带建设大潮。     

The first step of long-reach ADSL: smart DSL technology, READSL

Long-reach DSL (LDSL) is a project in the ITU, with the objective to increase the reach of DSL solutions. Range extended ADSL (READ-SL) is the first step in the LDSL project, driven primarily by requirements for North America. READSL extends the connectivity of G.992.1/G.992.3 based ADSL up to 18 kft, increasing the ADSL reach by more than 3 kft under the severe crosstalk conditions typically experienced in the North American access network. To cope with the multiple physical layer field conditions, READSL uses "smart" DSL technology based on a selectable mask procedure. READSL is spectrally compatible with the basis systems in the North American Spectrum Management Standard T1.417, and requires minimum changes to both the G.992.1/G.992.3 standards and product platforms. This article reviews READSL as a subset of the LDSL project.     

全球IPTV业务发展分析

介绍了欧洲、北美、亚太等三个地区的IPTV市场发展概况。以FastWeb为例，分析了运营商的IPTV运营模式，指出运营商把视频业务和现有电信业务进行捆绑，形成三重服务非常必要。以电讯盈料的内容策略为例，说明了开展IPTV业务的内容的重要性。     

The Asia-Pacific context for technology management

The Asia-Pacific has been the most dynamic region in the world. Yet beyond Japan, little has been published about technology management in this region of the world. In this introduction, we first describe the Asia-Pacific context through economic data, and then raise research issues     

Broadband wireless access solutions based on OFDM access in IEEE802.16

Broadband wireless access is the most challenging segment of the wireless revolution since it has to demonstrate a viable alternative to the cable modem and DSL technologies that are strongly entrenched in the last mile access environment. The Analysis, Research, and Consultancy (ARC) Group forecasts that the fixed wireless deployments in both homes and businesses will reach almost 28 million by 2005, with North America and Western Europe accounting for 24 percent and 27 percent of these, respectively. Whether the promise of BWA will materialize depends on its appeal to telecom operators from the perspective of deployment economics, where the critical factor is the ease of installation of broadband wireless subscriber units. This ultimately leads to nonprofessional installation of integrated all-indoor BWSUs. Consequently the physical layer (PHY) has to mitigate the very tough impairments that characterize these non-line-of-sight environments. In this context we overview the work of the one of the IEEE 802.16 standard subcommittee projects that deals with a BWA solution based on OFDM access (OFDMA) aiming at the most challenging NLOS scenarios     

Six steps to excellent customer service

As of November 2005, there were 6.2 million broadband customers in the UK and this figure is still growing. North and South America had approximately 49 million broadband users, Asia-Pacific 74 million and Europe 53 million. In the last two years, broadband has turned from a niche product into a truly mass-market product. This success story brings with it huge challenges for service providers who wish to give their broadband customers the support they need while at the same time running a profitable business in what is a highly competitive and price-sensitive market. This paper first discusses the issues that exist with supporting broadband customers. It then shows how taking an end-toend view of the complete customer experience, from when the problem first occurs right through to when the customer is happy that a permanent resolution has been achieved, enables service providers to identify the key support capabilities that are required in order to deliver an excellent customer experience. Finally, some innovative ways in which those capabilities can be realised, in a cost effective way, are identified.     

WiMAX开始在全球部署

从2006年年初以来，WiMAX在美国、欧洲、亚太，甚至在南美和阿拉伯国家等都在逐渐升温，从政府部门、监管机构，到运营商，都有积极的动作，使得WiMAX技术的施行和应用有了实质性的进展。目前给人的主要印象是，具有一定技术优势的WiMAX人气日高，已经被广泛接纳；亚洲将会成为WiMAX的重要市场；WiMAX将逐渐走向成熟，形成坚实的产业链，并降低成本；WiMAX和3G各有所长，互为补充，不会威胁3G的发展；作为爵前最大问题的WiMAX全球频率协调问题，也不会阻挡WiMAX前进的步伐。