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。     

全球DSL用户市场的发展情况

2001年全球DSL业务的发展依然保持高速增长的态势，亚态地区DSL用户数超过了北美的DSL用户数，跃居世界首位。本文介绍了北美、欧洲及亚太地区各主要运营公司DSL业务的开展情况。     

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。     

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。     

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。     

xDSL宽带接入技术

介绍了几种不同的xDSL技术,并对其传输容量和技术特点进行了比较。ADSL可充分利用现有的铜缆网络,技术成熟且标准化程度较高。HDSL也可利用现有电缆实现扩容,但速率恒定,不能根据应用改变而调整速率。各种DSL技术各有优缺点,今后还会有新DSL技术出现。     

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.     

数字用户线的充分利用

文章介绍公共交换电话网数字用户线(DSL)和非对称数字用户线(ADSL)的基本形式。概括说明在数字用户线上传送话音(VoDSL)的技术特点和传送通路化话音(CVoDSL)的优点及其相关问题。     

主流宽带接入技术的发展

电信网发展到今天，正在进入一个新的转折点，呈现出宽带化、IP化及业务融合化的趋势。电信网宽带化首当其冲的就是接入网的宽带化。近几年，为了适应网络和业务宽带化的要求，接入网的宽带化加快了步伐，正在向着多样化的方向发展，凸现出区别于其他专业网络最鲜明的特点。宽带接入技术分为有线接入和无线接入两种，有线接入技术的主流是基于电话线的数字用户线（DSL），基于光纤的宽带光接入技术，基于铜线的HFC和基于五类线的LAN。这几年市场上应用的主要是有线接入，其中主力技术是DSL。随着移动通信业务的迅速普及，无线宽带接入技术的发展也驶入陕车道，其中Wi-Fi，WiMAX等技术已经风靡全球。[编者按]     

Ethernet services over mobile WiMAX

Ethernet services represent a steadily growing portion of the fixed telecommunication market. To enable the provisioning of Ethernet services over IEEE 802.16e, the mobile WiMAX network architecture supports transparent Ethernet transport as an optional extension to the IP services architecture. Ethernet support is tightly aligned to the IP services network model, and leverages many data path and control plane functions from its IP sibling to keep the implementation and operation overhead low for the Ethernet extension. Mobile WiMAX provides IP services as well as Ethernet services over the same mobile access network. The intrinsic mobility support may create new deployment opportunities for Ethernet services. Initially, the Ethernet extension may be mostly used to realize wireless access for DSL networks based on the same network interfaces defined for the wired Ethernet-based DSL aggregation.     

从DSL论坛动态看宽带网络和业务发展趋势

随着宽带网络和业务的飞速发展,以宽带接入技术和宽带网络承载多业务应用为特征的DSL论坛得到越来越多的关注和认可,本文主要分析2007年上半年DSL论坛中主要技术热点,这些热点覆盖宽带接入网络承载多业务应用的框架、宽带接入支持组播技术、统一策略控制框架业务需求等多方面内容,并且通过这些分析可以看出目前国际主要电信运营商和设备厂商在宽带多业务方面的一些发展思路,从而给正处于行业转型期的国内运营商在宽带网络发展方面带来了一些启示.     

QoS in DSL access

Which enrichments are required for the DSL architecture to transform the DSL access network from a vehicle for best effort Internet access to a multiservice platform enabling added value conversational and data services? This article details an architecture for DSL access facilitating IP service guarantees leveraging the available QoS mechanisms in the transport-technology-specific data plane, while extending the control plane. Enhanced resource and information control, policy enforcement, and advanced IP connection establishment mechanisms are key elements for the network access provider to enter the value chain for delivery of IP services.     

Residential broadband architecture over ADSL and G.Lite (C.992.2):PPP over ATM

The objective of this article is to present the end-to-end broadband service and protocol architecture over DSL that has been adopted for both ADSL and G.Lite (PPP over ATM). G.Lite is a new form of DSL, and its characteristics are discussed. The article then presents a vision for the evolution of an analog modem-based service to G.Lite and ADSL services. The article explains the standardized architecture of PPP over ATM for DSL, and explores how the unique characteristics of G.Lite affect higher-layer protocols (PPP over ATM). Finally, it discusses a vision of how DSL will be deployed together with home networking to provide broadband services to multiple devices in a user-friendly fashion     

Realising the Potential of Access Networks Using DSL

This paper provides an overview of digital subscriber line (DSL) technology and describes some of the key technical issues facing BT's DSL engineering team. The factors which determine the theoretical information-carrying capacity of BT's access network cables are discussed to give the reader a feel for the potential of the existing access network to deliver broadband services. Transmission on this network will be subject to impairments which will limit the achievable capacity, and there is an urgent need to ensure that all DSL systems are spectrally compatible if the capacity of the network is to be fully realised.     

Realising the potential of access networks using DSL

This paper provides an overview of digital subscriber line (DSL) technology and describes some of the key technical issues facing BT’s DSL engineering team. The factors which determine the theoretical information-carrying capacity of BT’s access network cables are discussed to give the reader a feel for the potential of the existing access network to deliver broadband services. Transmission on this network will be subject to impairments which will limit the achievable capacity, and there is an urgent need to ensure that all DSL systems are spectrally compatible if the capacity of the network is to be fully realised.     

Digital subscriber lines: network considerations for ISDN BasicAccess standard

The authors review digital subscriber line (DSL) technology features and the key technical factors that have driven the development of the technology. The application of DSL technology to network access and the relevant standards activities that provide a framework for developing DSL performance requirements are considered. The important aspects of the physical and operational characteristics of the US loop plant that influenced critical technology choices are reviewed with an emphasis on the physical characteristics of the embedded loop plant and considerations pertinent to the economic provisioning and operations for ISDN (integrated services digital network) Basic Access. A review of the essentials of DSL technology for ISDN Basic Access is presented     

城域传送网中低阶交叉的需求及其解决方案

本文通过分析软交换引入带来的新需求,提出3种解决方案,经过不同角度的分析比较,给出建议。本文探讨了城域传送网过渡时期的建设方案。随着通信业务的进一步发展,城域传送网络必将逐步演进为基于IP或其他数据通信技术的下一代网络。     

Advanced DSL management

Today's digital subscriber line deployments are often conservatively engineered to function in a statistically worst case environment. Crosstalk is treated as unknown and uncontrollable random noise, even though it is manmade. Other impairments are often treated by simply adding margin to crosstalk. While this simplistic practice currently suffices, it often provisions unnecessarily low bit rates. This article shows methods that can increase these bit rates and decrease DSL failure rates. Data can be collected about individual telephone lines and cables from loop databases, by automated test equipment, or from DSL modems. This data may then be fed into an advanced DSL management system with a database of DSL loop and noise characteristics, and an analysis engine that tailors DSL deployments to the actual individual line characteristics, to increase provisioned DSL bitrates while simultaneously increasing reliability and lowering maintenance costs. The maximum service can be provisioned with high accuracy, eliminating many service activation failures. Automated maintenance routines can even isolate faults before a customer experiences them. Dynamic spectrum management (DSM) treats crosstalk as the manmade noise it is, and jointly optimizes DSL transmit spectra and signals to minimize crosstalk and maximize received signals, allowing substantially higher DSL speeds than current practice. This opens the door for new services, including symmetric enterprise services and full video service, with minimal physical plant upgrade.     

PTN在全业务运营趋势下的应用探讨

提出了实现全业务运营的网络融合需求;分析了移动回传、企业和家庭客户三大类业务的承载需求;针对移动回传需求,探讨了分组传送网在城域汇聚接入层的应用方案,以及后续支撑全业务运营的应用前景和演进策略。