从ADSL到VDSL

甚高位速数字用户线VDSL(Very High bit rate Digital Subscriber Line)技术是众所周知的非对称数字用户线ADSL技术的高速化版本。随着高速双向数据通信服务迅猛发展,ADSL实用化中的问题迫切急需解决,VDSL技术应运而生。 本文在回顾ADSL技术发展历程的基础上,重点介绍VDSL器件进展和它的应用实例,以便引起关注。     

VDSL与ADSL技术的比较

文章介绍了非对称数字用户线(ADSL)与甚高速数字用户线(VDSL)的关键技术，并对这两种数字用户线技术从调制技术、拓扑结构和应用环境等方面做了全方位的比较．     

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。     

VDSL系统上行信道的功率回馈方法

首先介绍了VDSL(甚高速率数字用户线)技术的应用驱动，接着描述了在VDSL系统上行传输方向上存在的“近一远”FEXT问题，以及为解决这个问题而提出的几种上行信道功率回馈方法及实现机制，并对它们的性能和实现复杂性进行了分析比较．     

新一代宽带接入技术——EDSL

以太网数字用户线（Ethernet Digital Subscriber Line,EDSL）技术是继ADSL、VDSL之后出现的新一代宽带接入技术。本文首先分析了EDSL技术的主要特点，在此基础上，结合中国电信双绞线资源丰富的特点，阐述了EDSL的主要应用形式。     

VDSL技术发展和标准状况

VDSL(Very—higk—speed Digital Subscriber Line)即甚高速数字用户线，利用频分复用的方法，在同一对电话双绞线内同时传送低频话带和数据两个部分。该技术支持对称速率或非对称速率方式传输。主要讨论VDSL技术近期的发展情况及国内外标准的状况。     

VDSL中调制方式的比较

甚高速数字用户线(VDSL)是数字用户线(DSL)家族中速率最高的接入方式.新一代VDSL速率最高可到100Mbit/s以上,包括对称传输和非对称传输以及多种不同的传输速率.由于VDSL的传输速率高,其对应的传输距离和其他DSL技术相比较短.调制方式是VDSL中的核心技术,目前有两种并存的方式,离散多音(DMT)与正交/调幅和无载波调幅/调相(QAM/CAP).文章主要介绍这两种调制方式,并从多个方面对其优、缺点进行比较.     

港湾网络VDSL解决方案

<正> 宽带接入网是当前宽带网建设的主要瓶颈,目前运营商采用的宽带接入技术一般有两种:以太网接入方式和xDSL接入方式。 自2001年开始,xDSL技术大规模应用,其中以非对称数字用户线(ADSL)和甚高速数字用户线(VDSL)技术应用最为普遍,VDSL技术因其带宽宽、出线率高和抗干扰性能好等特点,广泛用于宽带智能小区、高档住宅区和别墅区等地。     

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。     

一种基于VDSL的宽带接入解决方案

宽带接入网的接入技术有很多种,如HFC、ADSL、VDSL、LAN和FTTx等,其中VDSL接入技术因能满足快速接入和宽带多媒体业务的需求,越来越受到人们的青睐。 1.VDSL VDSL称为甚高比特率数字用户线,传送模式是基于IP和:Ethernet方式,通常采用DMT调制方式,在一对铜双绞线上实现数字传输。传输距离在1km之内,其速率理论值下行可达10-52Mbit/s,上行可达1.5-     

A Splitter Filter for Use with VDSL at the Cabinet

The design of a service splitter filter for VDSL has been studied for the case of VDSL deployed at a remote node such as a flexibility cabinet and where it is desired to apply VDSL signals over either telephony or ISDN signals originating in the telephone exchange. Even taking into account all of the requirements of telephony, ISDN, VDSL, HPNA and RFI, it is shown that a remarkably small and simple splitter will suffice.     

基于VDSL的以太网接入技术

介绍了基于VDSL的以太网接入技术（EoVDSL)。它结合了VDSL技术和以太网技术的优点，还可以与EPON技术相结合，作为一种经济高效的宽带接入方案。     

VDSL:下一代的数字用户环路技术

本文首先介绍了VDSL系统的相关规范 ,然后对系统的一些关键技术进行了比较 ,最后介绍了VDSL的发展现状     

VDSL数字用户环路接入及其关键技术

本文首先介绍了VDSL的体系结构,然后就实现VDSL接入的关键技术如线路编码技术,以及复用技术和回波抵消技术等相关技术进行了分析,最后指出了VDSL的发展现状和前景。     

TDD-VDSL兼容ADSL频谱的子频带抑制方法

VDSL是数字用户线技术中的最新技术,宽带接入的最佳方案之一。为了提高VDSL系统的传输速率,它有必要兼容现行ADSL系统的频谱。本文通过对VDSL系统的双工方式及兼容ADSL系统的可行性分析,提出了VDSL系统的可用功率谱密度及TDD-VDSL系统兼容ADSL频带的子频带抑制方法,并进行了仿真分析。结果表明在不同的运行环境下,都有很好的性能,是一种有效的实用方案。1     

Single carrier modulation technology for very high-speed digitalsubscriber line

This article gives an overview of very high-speed digital subscriber lines, including the main issues of VDSL system design, such as its basic architecture, applications, and data rates, as well as the technological challenges of practical implementation due to different loop plant realities and spectral compatibility considerations. Some specific characteristics of the VDSL transceiver startup procedure and high-level architecture, as well as a summary of first laboratory tests and field trials, are also presented. The article concentrates on VDSL implementations using single-carrier modulation, which integrates the well-known carrierless amplitude/phase modulation and quadrature amplitude modulation technologies. Currently, SCM technology is considered one of the main candidates for the VDSL standard in the United States and Europe, and internationally     

The Zipper prototype: a complete and flexible VDSL multicarrier solution

This article presents the prototype developed to prove the Zipper concept and contribute to VDSL standardization. This solution includes the hardware and software needed to demonstrate that the VDSL multicarrier is a feasible, flexible, high-performance, competitive solution. The prototype provides the network management and telemetry software needed to simplify system setup and performance evaluation, respectively. It includes two interfaces: one to plug a twisted pair cable or a cable simulator, and the other to connect the ATM transport protocol. A 155 Mb/s (OC-3 rate) ATM-SDH/SONET interface is provided too. The first measurements performed between two VDSL modems, with injected noise of 20 VDSL equivalent lines, show that it is possible to transmit (in downstream and upstream directions) payload bit rates up to 48 Mb/s at 300 m and up to 25 Mb/s at 1500 m using 0.5 mm copper cables. The prototype has been designed using a modular and flexible architecture able to allow future VDSL modem extensions. The reuse of this prototype is expected for other applications where OFDM technology applies.     

ATM passive optical networks and integrated VDSL

VDSL offers a cost effective solution for the provision of a full-service broadband access network. Standards are emerging that will define the line code, duplexing method, and spectrum requirements for VDSL. VDSL chipsets and modules are becoming available that allow the technology to be evaluated in the field. This article describes the architecture and hardware integration that has been performed in integrating VDSL technology into an ATM PON system     

Systems aspects of APON/VDSL deployment

The purpose of this article is to provide an overview of some system aspects allowing full service deployment over hybrid fiber-twisted pair access networks with a VDSL drop. Although VDSL and ADSL systems are similar from the point of view of transmission technology, there are differences in the architecture and implementation due to both the higher bandwidth and shorter copper loop length for VDSL. The VDSL drivers are given in the introduction. The next section describes the system architecture and the functionality of the various building blocks. Special attention is paid to optical feeder technology, for which APON is a well-suited technology. Concepts to reduce the cost of ownership are also discussed     

VDSL技术及发展

首先介绍了VDSL系统的主要技术要求、噪声环境及频谱兼容性，然后分析和比较了几种线路编码技术和双工方式，着重讨论了Zipper双工技术，最后介绍了VDSL的应用及发展现状。