基于HFC的宽带接入网关键技术

随着通信的发展和“信息高速公路”概念的提出,网络运营商越来越倾向集视频、话音、数据于一体的宽带综合业务,如今世界各国相继开发了基于现有铜缆的接入网技术高比特率数字用户环路(HDSL)和不对称数字用户环路(ADSL)、基于光缆接入技术的光接入网(OAN)、混合光纤同轴电缆(HFC)网络以及无线接入技术等宽带用户接入网技术,文章详细分析了HFC宽带接入网的网络结构及其关键技术。     

Video communications and services in the copper loop

There are several technologies available for providing access using the embedded copper loop plant. However, none of these technologies can provide a high-bit-rate digital transport capability (1.544 Mb/s) over the existing loop plant. The authors describe continuing advances in both VLSI implementation and signal processing algorithms that are making it possible to provide the high-bit-rate digital subscriber line (HDSL) for a repeaterless T1 capability within carrier serving areas (CSAs); asymmetric digital subscriber lines (ADSL) for a 1.5-Mb/s transport capability over the nonloaded copper loop plant; and the next-generation ADSL-II for a 3 to 4 Mb/s transmission rate over CSA ranges. It is argued that, coupled with advances in video compression techniques and recent standards activities in CCITT, these bit rates will allow local exchange carriers (LECs) to provide video communication and services using highly compressed digital video by allowing the LECs to use their existing embedded loop plant to enter the video market and establish a base of customers     

Optical networks for local loop applications

Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network     

HDSL技术在接入网中的应用

高速数字用户线（HDSL）技术利用现有的用户双绞铜线作媒介传输E1速率信号，是把高速数字业务接入到电信网的一种经济有效的解决方法。本文介绍了HDSL技术在应用中应考虑的几个问题，包括对HDSL设备传输码型的选择、线对数量、误码率选定、传输媒体和传输距离要求等。     

High bit rate digital subscriber lines: a review of HDSL progress

The author gives an overview of progress made in the evolution of technology to provide DS1 rate telephone access in a restricted segment of the loop plant without intermediate repeaters, loop conditioning, or pair selection in assignment. This technology is called the high bit rate digital subscriber line (HDSL). Discussed are background information on electronics in the loop plant and characterization of the tranmission environment in the relevant frequency band. The progress of HDSL study project of the American National Standards Institute (ANSI) is outlined. Analytical and theoretical studies to determine the limits on the transmission capabilities of the loop plant, motivated by the need to determine the feasibility limits of HDSLs, are reviewed. Also discussed is progress in technical work on suitable transmission formats. The possibility of an asymmetrical digital subscriber line (ADSL), transmitting at the DS1 rate from the central office to a remote distribution point, through the entire nonloaded loop plant is discussed     

HDSL的技术与应用

ＨＤＳＬ（高比特率数字用户线）技术是在铜线上传输高速数据的新技术，它对于提高现存的电话用户接入网的利用率有着重要意义。本文分析了ＨＤＳＬ技术产生的背景，详细讨论了应用于ＨＤＳＬ中的两种线路传输码：２Ｂ１Ｑ和ＣＡＰ，最后，阐述了ＨＤＳＬ的最主要性能，优点及其应用。     

市话线对作为高速接入的仿真结果

讨论绞线对传输的信道模型，给出实现HDSL、VHDSL与ADSL传输的方案与仿真结果，从而说明市话线对可以作为高速数据业务的一种有效的用户接入手段。     

高比特率数字环路技术

高比特数字用户环路（ＨＤＳＬ）技术是一种新的以绞线上实现高速数据传输技术，有“铜光纤”之称，本文就ＨＤＳＬ技术的内涵，ＨＤＳＬ标准体系，应用范围及ＨＤＳＬ设备系统步及的关键技术作了叙述，目的在于使大家对这一新有一个初步的了解。     

Local access optical networks

Both broadcast CATV and switched telephony access networks have evolved, over decades, to deliver their respective services efficiently. But these networks are not necessarily optimal for services that are rapidly emerging. This suggests that the access infrastructure will likely change in the future, driven by demands for new services and the costs of providing them. Will fiber optic networks play an important role? Trade-offs in desirable network properties (low initial costs, high capacity, flexible provisioning, enhanced maintenance and operations, etc.) are strongly influenced by the network architecture. We classify architectures on two characteristics: delivery mode (i.e., broadcast vs. switched) and carrier utilization (i.e., shared vs. dedicated), examining the trade-offs these imply with several examples of existing and proposed architectures. We show that optical networks can, by virtue of recent component development, be reconfigured to change their characteristics without changing the outside plant     

A discrete multitone transceiver system for HDSL applications

A discrete multitone (DMT) transceiver design for high bit rate digital subscriber line (HDSL) access is presented and analyzed. The DMT transmitter and receiver structure and algorithms are detailed, and the computational requirements of DMT for HDSL are estimated. At a sampling rate of 640 kHz, using an appropriate combination of a short finite-impulse-response (FIR) equalizer and a length-512 DMT system, 1.6 Mb/s data transmission is possible within the carrier serving area (CSA) at an error rate of 10^-7 on a single twisted pair. A significant performance margin can be achieved when two coordinated twisted pairs are used to deliver a total data rate of 1.6 Mb/s. In terms of a performance-per-computation figure of merit, the DMT system is an excellent candidate for HDSL implementation     

QoS management in trunk-and-branch switched Ethernet networks

A likely architecture for the future broadband access network will consist of a trunk-and-branch topology, with very high bandwidth trunks (e.g., 1-10 Gb/s), connected to high-bandwidth drops (or branches) to homes and businesses. A multihop switched Ethernet data transport can be used over this access network. Wang (see Internet QoS: Architectures and Mechanisms for Quality of Service, Morgan Kaufmann, 2001) discussed the benefits of upgrading the hybrid fiber coax plant into a distributed switched Ethernet trunk-and-branch network capable of fiber-like transmission speeds. This article focuses on QoS management in the proposed next-generation broadband access network (NGBAN) based on a multihop switched Ethernet network architecture. This network architecture and QoS management framework are more generally applicable, and we anticipate they will form the basis for the "last mile" independent of the physical medium.     

High-bit-rate digital subscriber lines

High-bit-rate digital subscriber line (HDSL) technology provides a simple, cost-effective solution for the rapid provision of a new digital telecommunication services direct to a customer's premises over existing twisted copper pair telephone lines. It makes full use of the existing network infrastructure and hence removes the need for the costly replacement of copper twisted pairs by alternative transmission media     

An evolvable ATM-based video network design supporting multipleaccess network technologies

This article describes an overall video network architecture with primary focus on the ATM subnetwork. The ATM subnetwork provides efficient switching capability for providing constant bit rate and variable bit rate video communication services. The ATM subnetwork can support multiple access networks like hybrid fiber coax (HFC), asymmetric digital subscriber line (ADSL), and fiber to the curb (FTTC). A broadband network controller is presented as the external controller for the ATM subnetwork which performs the functions of the session/network manager and the ATM-based connection management. The initial deployment of video is likely to be permanent virtual connection (PVC)-based, so a dynamic PVC-based scenario is described. The ATM switch architecture presented here has been optimized to support video applications. An evolution to the switched virtual connection environment and support of multiple services over the ATM subnetwork is also addressed. Traffic management schemes are discussed which provide the negotiated quality of service to the connections     

铜双绞线模型仿真与其信道容量分析

通过分析ADSL传输线路,对铜制双绞线进行了分析,包括线路特性、噪声特性的仿真.仿真中参考了6种典型的CSA环路作为分析的依据,讨论了近端串音(NEXT)、远端串音(FEXT)以及高斯白噪声对传输线路的影响,并将ADSL线路和HDSL、T1以及ISDN线路近端串音作了比较,最后得到ADSL信道的传送容量与线路长度的关系曲线.     

HSUPA技术及其发展

HSUPA(高速上行分组接入)是3GPP标准化组织为进一步满足数据业务需求在WCDMA/UTRA-FDDR6版本中提出的一种新技术,本文详细描述了引入HSUPA后WCDMA系统结构的演化,阐述了HSUPA中涉及的物理层混合自动请求重传(HARQ)、快速调度、短帧长、新扩频因子以及软切换等关键技术及其相应研究,最后对HSUPA技术及WCDMA的发展趋势进行了讨论.     

ADSL: a new twisted-pair access to the information highway

The asymmetric digital subscriber line (ADSL) takes advantage of the existing twisted-pair copper loop that currently provides customer access to the telephone network. An ADSL modem is placed at each end of the loop to create a high speed access link above the existing telephone service. Since ADSL makes use of the existing copper telephone line, its application in the telephone network can conceivably be nearly as ubiquitous as the public telephone network itself. With ADSL, it is possible to connect small numbers of customers to broadband services in areas where full upgrade to hybrid fiber coaxial or fiber facilities is not economical in the near term. ADSL systems offer a means to introduce broadband services using the embedded base of metallic loops in areas where optic fiber-based, hybrid fiber-coaxial radio systems or other broadband transport systems may not be scheduled for deployment in time to meet business needs and customer demand. The article concentrates on ADSL systems capable of at least a nominal 6 Mb/s payload transport toward the customer, in addition to associated upstream channels and symmetrical “telephony” services via nonloaded loops that comply with carrier serving area design guidelines     

Introduction to IEEE 802.3av 10Gbit/s Ethernet Passive Optical Networks （10G EPON）

In the competitive broadband access environment, providing access to ＂triple play＂ services （voice, video, and high-speed data） is an important way for both telephone and CATV network providers to increase their revenue. Passive Optical Networks （PONs） are a cost-effective, flexible, and future-proof medium for providing triple play services. The 1 Gbit/s IEEE 802.3ah Ethernet PON （EPON） and ITU-T G.984 2.5 Gbit/ s PON （GPON） are currently being deployed for triple play service access. However, high definition switched digital video service such as IPTV will require more bandwidth. This paper provides a tutorial overview of the IEEE 802.3av 10Gbit/s Ethernet PON （10G EPON） standard, including the ways in which it differs from EPON.     

High bit rate digital subscriber line echo cancellation

The authors explore the issues of complexity, precision, and dynamic range and practical implementation issues such as nonlinearities in high bit rate digital subscriber line (HDSL) echo cancelers. The approach taken is to study these issues analytically using computer simulations, and then to verify simulation results with laboratory prototyping. One of the objectives was to determine whether HDSL echo cancellation will be practical and cost effective within the next several years, consistent with the desire to develop and deploy a repeaterless T1 capability by 1993. Thus, attention is given to practical design issues