家庭共享ADSL访问

为了使两台PC同时共享ADSL（非对称DSL）访问，3Com公司提供了双链路的HomeConnect ADSL调制解调器，它有一个USB端口和一个以太网端口，使PC和便携机用户能同时进行高速ADSL因特网和电话访问。（新）家庭共享ADSL访问     

PowerQUICC通信处理器无所不在

自1995年推出PowerQUICC通信处理器以来，飞思卡尔的Power-QUICC系列处理器获得了广泛的应用。已经有500多家制造商的5000多种设备的设计中采用。其应用领域主要包括：数字用户线路（DSL）调制解调器，SOHO路由器，集成接入设备（1AD），远程接入服务器，数字用户线路接入多路复用器（DSLAM），     

DSL调制解调器测试方法

V90 Modem(调制解调器)已 不能满足Internet对宽带连接的需求。相应的，不同的数字用户线(DSL)技术被开发出来。其中，下行速率可达1.5Mb/s的G.Lite非对称数字用户线路(ADSL)标准最为引人注目(图1)。虽然DSL可提供所需要的宽带连接，但其应用环境充满了挑战。DSL的实现基于数字信号处理（DSP）技术，主要依赖于软件控制，并尽量避免芯片内的硬编码。目前，DSL传输采用的是电信通道设备连接到最终用户家中的铜质电话线。中心局（CO）到最终用户的距离非常不同。DSL Modem必须能够在这种传输距离变化很大而且室内布线情况复杂的…     

DSL论坛：中国DSL市场仍将高速增长

当前，全球宽带接入网络步人快速发展阶段，DSL作为主流的接入技术显现出巨大的实力。在目前举行的“2007宽带世界论坛亚洲会议”上，DSL论坛首席运营官Robin Mersh透露，全球的DSL（数字用户线路）用户总数已经突破2亿户，其中中国用户占20％。Robin Mersh在公布这一具有里程碑意义的数据时，援引了分析机构Point Topic的数据。     

土耳其电信携手阿尔卡特朗讯构建下一代DSL网络

日前,土耳其电信（Turk Telekom）宣布即将部署采用了阿尔卡特朗讯的VDSL2绑定及矢量化防串扰技术,以及阿尔卡特朗讯贝尔实验室展示的创新型＂DSL幻象模式＂（DSL Phantom Mode）技术的下一代DSL解决方案。得益于下一代DSL技术的强大优势,土耳其电信将为客户提供更快、更高品质的宽带服务,并将为土耳其构建知识型社会做出自己的贡献。     

2003年非洲(EMEA)在宽带增长中一路领先

来自PointTopic的一项宽带研究表明,2003年上半年,全球宽带线路数增长了24.3%,达到0.77亿。宽带线路包括DSL和cablemodem,其中DSL线数的增长占绝大部分,到6月底达到0.476亿,增长了30%,而cablemodem的增长相对较慢,为16.5%,达0.303亿。从各地区所占的比例看,亚太地区占42%,美国、欧洲、中东地区占35%,非洲(EMEA)占23%。从各地区增长的速度看,2003年上半年,EMEA的宽带增长速度位居首位,为34.5%,亚太地区为24.8%,美国仅为17.9%。尽管如此,美国仍然是全球最大的宽带市场,用户数 达0.209亿。而线路…     

数字用户线宽带优化系统设计方案

DSL（数字用户线）宽带优化系统每天定时到DSLAM（数字用户线路接入复用器）上收集线路各项运行的数据,按照设定的诊断分析算法,对一段时间里线路运行的大量历史数据进行分析,得出线路稳定性、端口达标率等指标,并给出线路上是否存在虚接、噪声干扰、纵向平衡性、阻抗非平衡等诊断结果。系统另一个主要功能是提供DSL线路整治决策手段和方案,哪些是可以通过优化线路上工作的模板参数,如噪声容限等,哪些是必须外派工单的。系统最后一个重要功能是测算出哪些线路端口速率有进一步提升的空间。     

双HDSL／SDSL模拟前端

双模拟前端芯片AFE2124大大地降低了DSIL（数了用户线）系统的尺寸和成本,同为它为两个数字信号处理器连接到外部协调混合电路和线路变压器提供所需的所有有源模拟电路。它对于HDSL（高比行军DSL）和SDSL（对称DSL）应用是最佳的。因率而变化、所以AFE2124特别适合于多速率DSL系统。它工作的数据率范围为64Kbps～1168kbps。AFE2124有两个片上HDSL模拟l前端（AFE）电路（通道A和通道B）其框图示于图1。每个AFE由个发送通道和一个接收通道组成,通过一个6线串行接口（3线用于发送通道,3钱用于接收通道）连接HDSLDSP它通…     

思博伦通信的解决方案兼容中国自动测试系统的标准

思博伦通信是第一家宣布推出符合中国电信业112 ADSL自动化测试标准的DSL服务保证解决方案的通信测试公司。依据DSL论坛统计，截止到2003年年底，中国已成为世界上拥有DSL线路数量最多的国家，线路数量达到1090万条。     

Cisco为中小型企业提供高速DSL路由器

CiscoSystemsInc.（思科系统）有限公司近日发布了Cisco1400系列。这一系列是数字用户线路（DSL）路由器的新一代产品,由O。c。105支持,专门面向中小企业和小型分局环境。Clll01400系列的第一个产品CISCO1401DSL路由器可以提供高速的Internet／Illtranet访问,并具有先进的保密性能,卓越的服务质量（QOS）和易于使用与管理的特点,CI。。0140o系列是CISSO全面的端到瑞DSL联网解决方案的一个关键组成部对。“CISCO1401DSL路由器满足了中小型企业对安全、高速和高效益远程访问解决方案的需求,并进一步证明了我们对于把DS…     

SDSL — it is more than just a simple voice/web access

SDSL (Symmetrical Digital Subscriber Line) is a future-proof wideband access technology for small business and residential users via twisted pair. The original motive for development of new xDSL technologies was the desire on faster Internet access for classic telephone users via copper line. Especially the development of SDSL with its symmetrical nature presents new possibilities itself. For instance SDSL copes excellently with the growing demand for carrying several voice connections via a single copper line always called VoDSL (Voice over DSL), the new generation of voice services for small enterprises and the small office/home office (SOHO) market. We will summarize the features of SDSL and its implementation and have a short look at the actual standardization items. Different Voice over DSL approaches and the use of SDSL as in-house installation will be discussed.      

Video on phone lines: technology and applications

This paper reviews the telephone loop plant characteristics, current DSL (digital subscriber line) technologies, recent efforts in video coding standards, and the interrelationship between DSL technologies and visual communications over subscriber lines. In overview of the loop plant characteristics we examine its physical makeup and transmission properties, where for the latter we discuss frequency and time responses of wire-pair lines and the impairments of echo, crosstalk, impulse noise, and radio frequency interference. We trace the historical development of various DSL technologies and comment on possible future evolution. Transmission technologies used in the ISDN basic-access DSL, the high bit-rate DSL, and the asymmetric DSL are portrayed. And the issue of spectrum compatibility among different transmission systems is explained. Several important video coding standards are briefly described, including ITU-T's H.261 and ISO's JPEG and MPEG series, which are either completed or emerging. The synergistic relationship between these standards and the DSL technologies is elucidated. As a result, DSL technologies provide the potential of delivering certain broadband services well in advance of direct fiber access for telephone subscribers     

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.     

Loop makeup identification via single ended testing: beyond mereloop qualification

Digital subscriber lines (DSLs) offer carriers the possibility of exploiting the existing loop plant to deliver high-speed data and voice services. However, before deploying DSL, local loops must be tested in order to see whether they can support service, and at what level. In fact, there are many impairments that could disqualify a loop for supporting DSL services: load coils, excessive loop length, bridged taps, and wideband noise. Single-ended automatic qualification is essential for achieving low-cost deployment of DSL, since it allows loops to be qualified in bulk and does not involve any human intervention at the customer's location. An even more ambitious challenge is to fully characterize a loop, i.e., to identify its loop makeup. If it is feasible to perform loop makeup identification via single-ended measurements with sufficient accuracy, then operators will benefit substantially because, besides qualifying a loop for DSL service, this capability will allow the updating of telephone company loop-records. These records can in turn be accessed to support engineering, provisioning and maintenance operations. Despite its potential importance, the possibility of achieving loop makeup identification via single-ended measurements is not widely addressed in the current literature. In the present contribution the feasibility of loop makeup identification via single-ended measurements is presented     

Broadband and the baby bells

Wireless access may be the way to get around the phone and cable monopolies. New rules adopted by the U.S. Federal Communications Commission (FCC) in February may: (A) Reboot the stalled U.S. telecommunications industry by spurring the construction of broadband digital subscriber line (DSL) and fiber telephone networks. (B) Kill any chance of a competitive DSL market in the United States, prolonging the telecom sector's malaise. (C) Be largely irrelevant to broadband's future in the United States, as decisions due later this year from the FCC will matter much more to the growth of true high-speed networks.     

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。     

Systems considerations for the use of xDSL technology for dataaccess

A variety of signal processing techniques have been developed over the past 10 years to increase the bit rate of digital transmission through telephone loop twisted pairs. The ISDN basic rate access 2B1Q digital subscriber line (DSL) was the first technology of this type to be deployed commercially at 160 kb/s full-duplex transmission on a single twisted pair. Other transmitter/receiver circuits have been developed over the years that support symmetric and asymmetric data transmission from several hundreds of kilobits per second to several megabits per second using the 2B1Q line code in the case of HDSL and various modulation techniques (QAM, CAP, and DMT) in the case of ADSL. These more recent forms of xDSL circuitry have begun to be used to provide commercial Internet access. This article analyzes the system level considerations for using these technologies in the increasing complex loop network of telephone companies. A “next generation” of xDSL access system is proposed, and the requirements for such a system are discussed     

From voice‐band modems to DSL technologies

This paper provides an overview of the evolution of digital transmission in the copper access network from voice‐band modems to Digital Subscriber Line (DSL) technologies. The various types of DSL technology are described. Copyright © 2001 John Wiley & Sons, Ltd.     

A frequency-domain approach to crosstalk identification in xDSLsystems

Crosstalk between multiple services transmitting through the same telephone cable is the primary limitation to digital subscriber line services. From a spectrum management point of view, it is important to have an accurate map of all the services that generate crosstalk into a given pair. If crosstalk is measured via modem-based methods, i.e., while a digital subscriber line (DSL) system is running, what is measured is the crosstalk in the bandwidth of the considered DSL system. For this reason, DSL services running on adjacent pairs may not be detected if their bandwidth is not significantly overlapping with the bandwidth of the disturbed system. This is a major drawback of modem-based system identification techniques since, from a spectrum management point of view, it is important to be able to identify all crosstalkers. We address the important problem of crosstalk identification when the pair under test does not bear DSL services, i.e., via a non-modem-based approach. Crosstalk sources are identified in the frequency domain by finding the maximum correlation with a “basis set” of representative measured crosstalk couplings. The effectiveness of the proposed technique is also verified on the basis of real crosstalk measurements performed on actual cables. Finally, new techniques based on multiple regression and best basis selection are also discussed     

Cable measurements supporting xDSL technologies

The ongoing developments in the field of high-speed data transmission over twisted-pair cables (DSL-Digital Subscriber Line) leads to methods that can exploit the transmission media with increased efficiency. MIMO (Multiple-Input Multiple-Output) transmission, i.e., the coordinated use of many pairs within a bundle, is such an emering DSL technology. A further goal is to maintain a certain transmission quality in the presence of non-DSL noise. For example, cancellation techniques to combat narrowband radio interference, which is generated by radio amateur transmitters and may be picked up by the wire close to the subscriber or by the in-hourse wiring, become important. The efficiency of these techniques strongly depends on cable properties that have not been the focus of cable measurements so far. This paper gives an overview of special cable measurements and shows their importance for future DSL technologies.