ADSL技术的实现及标准化

对称数字用户环路（ＡＤＳＬ）技术是数字用户环路（ＤＳＬ）系统的一种解决方案。ＤＳＬ系统是基于铜双绞线,用来在公用电话交换网（ＰＳＴＮ）上提供宽带业务的一种实现方法。传统的电话线传输话音和数据时只使用３００Ｈｚ到３．４ｋＨｚ的带宽,ＤＳＬ则使用 ３．４ｋＨｚ以上的部分频率资源。 目前已出现了多种ＤＳＬ技术：综合业务数字网（ＩＳＤＮ）提供了第一个ＤＳＬ服务,采用了基本速率接口（ＢＲＩ）,用 ２ＢＩＱ（两比特、四电平）线路编码在长达６公里的本地环路上以ＩＳＤＮ ＢＲＩ速率传送数据,其中应用的主要技术是判定…     

B—ISDN的网络互连

介绍了宽带综合业务数字网（Ｂ—ＩＳＤＮ）与城域网（ＭＡＮ）、局域网（ＬＡＮ）、综合业务数字网（ＩＳＤＮ）及帧中继间的网络互连。     

ISDN数据终端适配卡的研制

本文研制了一种综合业务数字网（ＩＳＤＮ）数据终端适配卡。该卡采用ＥＳＡ总线微机接口，数据和控制信息可在微机主存和适配卡间直接并行流通，使接口的通道速率高达６４ｋｂｉｔ／ｓ；具有Ｓ／Ｔ和Ｕ双接口，既可通过Ｓ／Ｔ接口和网络终接器ＮＴ１相连，又可通过Ｕ接口和具有ＩＳＤＮ功能的交换机相连；利用Ｄ通道的ＨＤＬＣ规程控制顺实现了Ｂ通道的部分数据链路层协议；采用ＭＩＴＥＬ公司的ＩＳＤＮ专用大规模集成电路，系统具     

LAN与MAN互连──B－ISDN一项有效的应用

本文讨论ＬＡＮ（局域网）与ＭＡＮ（都市网）通过Ｂ－ＩＳＤＮ（宽带综合业务数字网）来进行互连的问题。这种互连显示出Ｂ－ＩＳＤＮ具有真实前途的一种应用，因为它可避免常规ＬＡＮ互连中大多数传统缺点。然而，必须选择正确的协议才能有效地利用Ｂ－ＩＳＢＮ。为了能及早经济地实现ＬＡＮ／ＭＡＮ互连，早期就应仔细考虑互连的要求。简言之，人们期望Ｂ－ＩＳＤＮ新的可能性将开辟有吸引力的新的ＬＡＮ互连的可能性，同时提供现时尚无法达到的性能。这一定可以促进该地区通信迅速发展     

B—ISDN的一种重要应用

叙述局域网（ＬＡＮ）和城域网（ＭＡＮ）通过宽带综合业务数字网（Ｂ—ＩＳＤＮ）互相连接；ＬＡＮ／ＭＡＮ互连的要求和接口设备。     

基于PowerPC 860开发板的Q.921协议软件包的实现

软件系统相关的技术背景及协议 １．ＩＳＤＮ技术背景 随着计算机和通信事业的飞速发展,交换和数字传输设备、以及其他数字技术被广泛地应用于数据、语音和图像的传输中,人们日益感到传统的各种通信网相互独立的局面,限制了通信业的发展,因此,迫切需要一种能够同时传输并处理多种数据的网络,综合业务数字网（ＩＳＤＮ）也由此应运而生。 ＩＳＤＮ技术经过十余年的发展,人们逐渐认识到,提供标准的用户／网络接口是实现综合业务的关键。因为只要用户拥有了能够与现有的各种通信网络接续的数字用户交换机和标准的ＩＳＤＮ用户／网络接口,就可以通过同一条用户线路利用多种终端进行通信。 通过一个多用途的标准用户／网络接口用户可以选择并利用ＩＳＤＮ的各种通信业务。这种标准的用户／网络接口所具有的呼叫控制功能是以用户／网络间协议的形式规定的。 ２．Ｑ．９２１协议简述 国际电信联盟ＩＴＵ—ＴＱ．９２１协议规定了ＩＳ－ＤＮ用户／网络接口数据链路层技术规范特性,它通常和ＩＳＤＮ用户／网络接口的物理层一起,为第三层提供通信服务。在ＩＳＤＮ用户／网络接口处,数据链路层的协议采用Ｄ通路上的链路接入协议（ＬＡＰＤ）。ＬＡＰＤ的主要目的是经过ＩＳＤＮ用户／网络接口采用...     

接入网中的V5接口

接入网中的Ｖ５接口吴凤修接入网（ＡＮ）是通信网的重要组成部分，是本地交换机（ＬＥ）和用户之间的传输系统。根据光纤和ＳＤＨ技术的应用及数字通信业务的要求，ＡＮ必须做到在ＬＥ与用户终端设备之间实现透明的数字连接，也就是ＬＥ应具有数字用户接入的数字接口，即...     

VSAT在ISDN中的应用（下）

ＶＳＡＴ在ＩＳＤＮ中的应用（下）ＡｂｄｕｌＨａｍｉｄＲａｎａ等４综合ＩＳＤＮ结构和实施上一章确定了六种配置的潜在应用。综合地面／卫星的ＩＳＤＮ网络配置称作卫星链路ＩＳＤＮ通信（ＳＬＩＣ），选用来证明设想的实施。所以选用这种配置是由于许多公司和政府机构...     

光纤传输在各种通信和广播网中的应用

本文阐述光纤传输系统在公用通信－宽带综合业务数字网（Ｂ—ＩＳＤＮ），在专用通信－局域网与城域网（ＬＡＮ／ＭＡＮ），在有线电视广播网（ＣＡＴＶ）以及在移动通信蜂窝网（ｃｅｌｌｕｌａｒ）等各种通信网和广播网中的应用，并介绍它们的特点、相互差异，以及发展趋向。     

多媒体通信技术（三）：多媒体通信的信息处理技术

０引言 多媒体通信网为多媒体提供一个传输环境,网络的带宽、信息交换方式以及高层协议直接决定着传输及服务的质量。目前绝大部分的多媒体业务都是在现行的各种网络上运行的,并且按照多媒体通信的要求对现有的网络进行改造和重组。目前的通信网络可大体上分为３类：１类为电信网络,如公用电话网（ＰＳＴＮ）、分组交换网（ＰＳＰＤＮ）、数字数据网（ＤＤＮ）、窄带和宽带综合业务数字网（Ｎ－ＩＳＤＮ和 Ｂ－ＩＳＤＮ）等;２类为计算机网络,如局域网（ＬＡＮ）、广域网（ＷＡＮ）等;３类为电视传播网络,如有线电视网（ＣＡＴＶ）、…     

Multi-rate ISDN

Multi-rate integrated services digital network (ISDN) is a new technology for providing dialed-up, circuit-switched, isochronous communications for bandwidths from 128 kb/s to 1.536 Mb/s (DS-1) or 1.920 Mb/s (CEPT-1). Multi-rate ISDN provides a simple way to extend ISDN network services to match the higher bandwidth requirements emerging for videoconferencing, multimedia, imaging, and other high-speed applications. Using this technology, network service providers can offer high-speed connectivity within the boundaries and benefits of existing, circuit-switched, central office and transmission equipment. Only minor changes are required in the operations administration and maintenance and provisioning (OAM&P) procedures associated with multi-rate ISDN, versus existing ISDN transmission and central office maintenance procedures     

光纤通信网技术的发展

本文综述公用通信网和专用通信网利用光纤传输的发展趋向。公用通信网将向数字化、综合化、宽带化、和智能化发展,最终成为B-ISDN。为此,通信网将从铜线过渡至光纤,从窄带过渡至宽带,从异步过渡至同步,从电路交换过渡至分组交换。全国传输网将是同步光纤网(Sonet),最后必然是“光纤到家”,从用户至用户的全程传输是光纤。另一方面,大企业、大机关急于实现自动化,各自建设专用的光纤局部区域网(LAN),从计算机通信进至综合业务。很可能专用ISDN比公用ISDN更早出现。住宅区需要通过光纤选收电视(CATV)。未来的公用市内用户网和专用局域网,将为光纤产业开辟最大市场。     

Southwestern Bell Telephone's ISDN experience

Southwestern Bell Telephone's (SWBTs) integrated services digital network (ISDN) experience has been heavily influenced by the realization that from a customer perspective, the most important aspects of ISDN are its applications. The authors describe the following ISDN applications that SWBT has been exploring: desktop conferencing; asynchronous protocol conversion to SNA/SDLC; VTAM INN link replacement; asynchronous protocol conversion to SNA/SDLC with multiplexing; remote 3174 multiplexing via B channel packet; remote 3174 multiplexing via B channel packet and NPSI; 327X emulation via SIMPC, SIM-VTAM, and NPSI; 327X emulation with QLLC and NPSI; asynchronous access to private packet-switched networks; asynchronous access to UNIX host; asynchronous access to UNIX host via PAD and X.25 multiplexing; 327X coaxial cable elimination; extended local area network with passive bus; asynchronous access to Ethernet terminal server; dedicated line replacement (64 kb/s); asynchronous modem pooling (out-dial); asynchronous modem pooling (in-dial); ISDN wide-area networking; ISDN data gateway; gateway to AppleTalk network; application processor features; circuit-switched compressed video; and Ethernet LAN bridging     

Interworking IEEE 802/FDDI LANs via the ISDN frame relay bearerservice

The author presents a generic architecture for interconnecting LANs (local area networks) through the ISDN (integrated services digital network) bearer services, particularly the frame relay bearer service. The architecture is derived from the IEEE 802.1 MAC (medium access control) bridge and ISDN frame relay standards. An algorithm for MAC/ISDN address resolution that makes minimal use of the WAN (wide area network) bandwidth (which is potentially the most expensive resource) is presented. The algorithm uses a MAC/ISDN address resolution server to resolve addresses for new stations, the resolution in all other cases (e.g. stations moving from the ISDN address to another) being fully distributed. To prevent a server failure from inhibiting communication to new stations, a backup server may be provided. A practical implementation of the architecture has been found capable of supporting full throughput at ISDN hyperchannel rates (384-1920 kb/s) for all IEEE 802.3 frame lengths. Frame relay is seen as having a number of important advantages for LAN interconnection, including the following: a large number of virtual circuits available, giving the potential for a rich interconnection architecture with single-hop connections across the ISDN; and low processing overhead enabling efficient use of ISDN channels, including ISDN hyperchannels (384-1920 kb/s)     

ISDN Implementation Stategy of the Deutsche Bundespost--From the ISDN Pilot Project to Commercial Services

The first section of this paper defines the Deutsche Bundespost concept of ISDN, the services to be integrated, and the various ISDN components. The second and third parts of the paper cover the ISDN Pilot project and the offering of commercial ISDN services in the Federal Republic of Germany. The implementation strategy is briefly shown together with some outlook of the integration of broad-band services into ISDN. The last part describes strategic development toward an integrated services universal network, offering all kinds of telecommunication services including individual communication as well as broadcast services such as radio and TV program distribution.     

Migration to broadband ISDN

The current state of telecommunications in Japan is briefly discussed, with particular reference to broadband services. Experience with the migration from the analog telephone network to the present narrowband integrated services digital networks (ISDN) is described. Three strategies for the transition from narrowband ISDN to broadband ISDN are examined. The market-driven strategy is to replace existing metallic subscriber loops with optical media, wherever possible, even if only narrowband services are required, with the expectation that these subscribers will eventually use broadband services. The service-oriented strategy entails putting into place a flexible and multipurpose platform that would also allow HDTV distribution and bidirectional communications. Early installation of such a platform would allow for the early announcement of broadband services, which would in turn stimulate demand. The benefits and drawbacks of each of these strategies are discussed. The advance-investment strategy is to press ahead with the introduction of optical subscriber loops to accelerate technological innovation, even if the cost is somewhat high. Other issues that are important to the migration of broadband ISDN are noted     

Application profile for ISDN

The authors examine some key data processing applications to be used in conjunction with the voice and facsimile services as a platform for deploying ISDN (integrated services digital network) in North America. Special emphasis is placed on the emerging standards of both Accredited Standards Committees (ACS) T1 and X3 in an attempt to harmonize the computer and telecommunication industries towards providing the user with an integrated platform that is vendor-transparent and ubiquitous. This generic platform, which spans a large spectrum of businesses, is presented as a base context for defining user-specific needs and incubating the applications that directly relate to businesses. Distributed transaction processing, electronic data interchange, information retrieval, electronic mail, and file transfer together with seven supplementary services for voice and G4 facsimile are proposed for ISDN deployment in the marketplace. The authors describe how the relevant standards may be exercised through the various ISDN channels and emphasize the value of the North American ISDN User's Forum for commercializing this platform     

The value of ISDN for banking applications

US Bank's experience with a number of applications supported by Northern Telecom's DMS-100 integrated services digital network (ISDN) is discussed. Some of the applications that US Bank has been using, as well as some applications planned for near-term implementation, are described. The current applications supported by ISDN are the centrex telephone; message desk call receptionists; systems network architecture (SNA) host access; automatic teller machines; point-of-sale network; and wide-area networking. Future ISDN applications include support of loan approvals and service kiosks     

Implementation in Japan [ISDN]

INS-Net, Nippon Telegraph and Telephone's (NTT's) commercial integrated services digital network (ISDN) service, is described. There are two types of INS-Net service. INS-Net 64 provides basic rate interface service, and INS-Net 1500 provides primary rate interface service. The implementation of INS-Net and the promotion, application, and penetration of ISDN services are discussed. It is argued that as the number of useful applications grows, the number of subscribers will rise accordingly, particularly among business users. This increased volume of both applications and users will in turn lead to lower ISDN CPE costs, and will make ISDN an indispensable means to business activities in the 1990s