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     

An Integrated Voice/Data Terminal with Simple Synchronization Circuits Using an 80 kbit/s Ping-Pong Method

With recent digital technique progress, digitalization is spreading to subscriber loop systems. In-house systems will be digitalized earlier than other systems. In in-house networks, a pingpong method, especially an 80 kbit/s ping-pong method, using an existing cable pair, is superior to other digital transmission methods due to the sample system structure. For office use, a digital subscriber terminal is required to offer integrated services. However, the already reported 80 kbit/s method is insufficient to provide simultaneous and independent integrated services. This paper presents an 80 kbit/s ping-pong method which has 72 kbit/s capacity for the voice and data communications, so as to provide such integrated services. Furthermore, an experimental integrated terminal, which has simple synchronization circuits, is described.     

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。     

Services Integration and Multiplexing for Broad-Band Communication Systems

In broad-band communication networks, a number of services are simultaneously available to the subscriber. The issues of service integration and multiplexing techniques, and their impact on network topologies, are addressed in this paper. Alternative realizations of broadband networks, together with necessary electrical and optical components, are discussed. A comparison between the different alternatives is also made.     

Implementation of a broadband integrated services hybrid network

The issues involved in the design of a broadband integrated services digital network (B-ISDN), that utilizes optical fibers in the subscriber loop, are considered. A hybrid scheme that provides integrated access to ISDN and broadband services by delivering voice/data signals in a digital format while using an analog format for full-motion video services to subscribers is proposed. The discussion covers planning for a B-ISDN, the system concept, implementation, the loop fiber network, subscriber equipment, and cost comparison and analysis     

Electronic Systems and Equipment for Evolving Loop Plant

This paper discusses a French plan for enhanced subscriber service, and some of the systems and equipment that will meet these goals on existing loop plant. Since 1972, the French PTT has been installing digital central offices at the national, regional, and local levels. Coverage is expected to reach 10000000 lines by 1985, so that when integrated services can be offered, the nation will be ready to take advantage of them. A PTT-sponsored program, directed toward all-digital subscriber loops, has revealed four principal phases. The first of these is already in progress: both digital and analog pair-gain systems are now being installed on existing loop plant. Soon to come is the second Phase: residential subscribers will be able to obtain two-channel subscribercarrier installations, with the carrier channel supporting data services, independent of the voice service on the same loop plant. Integrated Services Digital Networks, the third phase, should stretch the French loop plant to maximum capacity. When the demand for broad-band services overrides the capabilities of the existing copper pair plant, fiber optics cable installation will be fully planned and implemented as the fourth phase.     

Progress Towards Digital Subscriber Line Services and Signaling

With digital connectivity, future subscribers will be able to exercise local and network services involving the routine delivery, management, and processing of information. Accelerated by rapidly advancing technology, the evolutionary process towards digital connectivity and integrated voice and data services in the network is underway. This paper describes the methods of integrating voice and information capability into the telecommunications network. The attributes of this network will include the availability of digital connectivity directly to the subscriber, the availability of a robust signaling means between the subscriber and his local switching office, and common channel signaling to implement all interexchange signaling. Issues of interest include an overview of digital subscriber connectivity, signaling and information structures for these kinds of lines, communications protocols, and general network considerations for the provision of information services. Partitioning of intelligence between intelligent subscriber terminals and controllers and their switching system is investigated. The use of message and virtual channel switching facilities to handle limited information rate services is discussed. Finally, an exploratory digital subscriber line under investigation at Bell Laboratories is described.     

Digital video transmission for broadband networks

The information society to come is characterized by a large information flow in the integrated broadband network. Today it is the distribution of TV programmes that requires high transmission capacity. This leaves the cable operator with a problem. How should the CATV network of today be constructed? It must fulfil the need for distribution now and it must be prepared for new services to come. Some aspects of the above problem are discussed in this paper. It is emphasized that digital techniques as well as optical fibre transmission should be included in a modern cable network. The Danish DOCAT network concept is presented as one way to accomplish this. DOCAT combines optical fibre transmission in the trunk network with conventional coaxial techniques in the subscriber network.     

Photonic highway: broad-band ring subscriber loops using opticalsignal processing

The introduction of optical signal processing technology into transmission systems and basic experiments with optical drop/insert using bistable laser diodes are discussed. With broadband integrated services digital network (B-ISDN) architecture and technology now under study, optical signal processing (OSP) is being considered to increase network capacity and flexibility. B-ISDN will require over 40 Gb/s in the feeder loop that connects the central office and remote terminals having drop/insert function. Remote terminals will process large amounts of high-speed data. An OSP-based broadband subscriber loop photonic highway that uses a ring architecture linking photonic access nodes (PANs) that directly process optical signals is proposed. Each PAN has an optical drop/insert function and can synchronize optical frame signals using a proposed optical sampling memory. Optical drop/insert experiments confirmed the feasibility of the proposed method     

Positioning the Subscriber Loop Network for Digital Services

The need to enhance the digital transmission capability of the local loop network to provide for new services is widely recognized in the telecommunications industry. Companies around the world [1]-[3] have been working towards this goal and plan to use digital loop carrier (DLC) to meet this demand. Although this approach is generally accepted, there has been little information presented on how to plan for the evolution of the local plant. To address these pressing issues, the Bell System is introducing a concept called fundamental subscriber carrier planning (FSCP). This paper discusses the impact that digital services will have on the subscriber loop network, including loop plant design requirements necessary to position the network for up to 64 kbit/s digital services. Existing cable plant has the capability to support most digital services, but there are specific design requirements that are quite different from those required for the "typical" analog voiceband service. This paper reviews the need to position the loop for digital services, and substantiates the major conclusion that digital loop carrier technology offers a significant advantage when provisioning for digital services.     

The wireless art and the wired force of subscriber access

Different technologies for subscriber access are put side by side. Starting from the various transmission media characteristics of all systems, the well-known twisted pair lines with their corresponding digital subscriber line services are evaluated against wireless local loops, communications over ubiquitous power lines, high-bandwidth cable modems, and mobile radio. Each technology has its advantages and disadvantages. The different technologies will find their fields of applications. Most networks will have to provide a mixture of solutions for individual subscribers and customer segments to meet their boundary conditions. As a result, the future of subscriber access is a hybrid solution     

Configuration and Characteristics of a Fiber-Optic Video Distribution System

A multiservice fiber-optic subscriber system using wavelength division multiplexing technology has been developed by Nippon Telegraph and Telephone Corporation to provide both 64 kbits/s and broad-band communication services on a single multimode fiber. The subscriber network is formed in a star topology to facilitate bidirectional connection. The system was put in service in March, 1985, as part of the information network system (INS) model system. This paper describes the configuration and characteristics of the video distribution system of this fiber-optic subscriber system. The distribution system uses analog baseband video transmission at a 0.89μm wavelength. The video channel selection is made by an FDM video tuner installed in a central office. The overall performance successfully met design objectives.     

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。     

Technologies towards broadband ISDN

It is argued that it is vital to form a sound strategy for developing broadband integrated services digital network (BISDN) technology and services and deploying them in the field, so that smooth migration from the existing network is accelerated. Three major steps in this context are to expand fiber networks into the subscriber loop area to provide broadband capabilities everywhere, to construct a universal digital network that facilitates smooth evolution from the existing network to the broadband network of the future through deployment of (SDH) synchronous digital hierarchy transmission systems, and to integrate both services and network components through introduction of asynchronous transfer mode (ATM) technologies. Development efforts now being carried out at Fujitsu and Fujitsu Laboratories along this line are described, and the impact on network construction and service offerings is indicated     

Design of a Switched Broad-Band Communications Network for Interactive Services

The congestion in broad-band communications networks resulting from the increased demand for interactive services is considered. It is shown that services such as a video library could not be provided to the majority of subscribers in a conventional CATV network. A design is developed for a space division multiplex broad-band network which can be expanded at minimum cost to meet an increasing demand for interactive services. The network contains two signal distribution networks: a cablecast system similar to the Rediffusion system, and a switched communication network providing point-to-point circuits for both one-way and two-way services. All broad-band signals are transmitted to the subscribers in the 1- to 10-MHz spectrum, permitting the use of twisted pair video cables and a minimum number of cable amplifiers. The broad-band cable network (BCN) is organized around 15 local switching exchanges and one central exchange. Multipoint switches in local exchanges under wired-logic circuit control connect individual subscriber communication lines to any channel. Crosspoint matrix switching groups in the local and central exchanges connect communication circuits in the broad-band communication network under programmed computer control. This network is accessed via links terminating on one channel of the multiposition switches. Per-subscriber costs are estimated to be 190 dollars for a cablecast system serving 3800 subscribers. Additional expenditures per subscriber of 40 dollars for fixed costs and 40 dollars for variable costs would provide interactive services. The range of interactive services provided would be extremely flexible, including both one-way video library service and point-to-point two-way communications.     

New concepts and technologies for achieving highly reliable andhigh-capacity multimedia wireless communications systems

The rapid growth of multimedia wireless communications services forces the development of advanced digital wireless systems with high reliability and high speed as well as flexibility for varying traffic conditions. To achieve such advanced wireless systems. New system design concepts different from the conventional ones aiming at increasing system capacity for voice transmission would be required. Since multimedia wireless communications require high quality, high speed, and high flexibility as well as temporary and spatial control of traffic under severe fading environments, the so-called conventional system design concept will be insufficient. New system design concepts and techniques for achieving highly reliable and high-capacity multimedia wireless communications are discussed using both time division multiple access (TDMA) and code division multiple access (CDMA) systems. The demands for high-speed and high-reliability mobile, personal, and multimedia wireless communications services strongly require matching with the trunk network constructed by a broadband optical fiber system or wired system     

Évolution du réseau français vers le RNIS*

The French « Direction Générate des Télécommunications » (dgt) which has been a pioneer in the field of digital technologies with the introduction of the Alcatel E10 system in the beginning of the seventies, is now deeply involved in the process of providingISDN services to its customers. Thanks to a high degree of digitalization,dgt is able to implement a strategy of evolution based on the network which is able to support both the analog andisdn traffic. This paper intends to highlight the following steps of evolution which are now underway: — fast digitalization of the network and an early offer (1986) of a transparent 64 kbit/s switched service (Transcom) ; — introduction ofccitt no 7 system ; — introduction of a new subscriber unit enabling both analog and digital connections ; — enhancement of the sofware of existing exchanges to provide new services. These evolutions will enabledgt to offer beyond the present Transcom service and by the end of eighties a full range of isdn services on a nationwide basis.     

Wireless loops: What are they?

Several loop applications of wireless technology are aimed at reducing the cost of deploying communications services ranging from telephone to wideband video. In these applications, wireless links replace a portion of a wireline loop from a central location (a central office or cable headend) to a subscriber. The replacement of labor-intensive wireline technology by complex mass-produced integrated electronics in wireless transceivers is projected to reduce the overall cost of the resulting loop. These wireless loop applications attempt to provide existing communications services or small modifications to existing communications services. A different interpretation of a wireless loop makes use of low-power digital radio technology to provide the last thousand feet or so of a loop. Low-power low-complexity wireless loop technology in small base units can be integrated with network intelligence to provide the fixed-infrastructure network needed to support economical personal communications services (PCS) to small, lightweight, low-power personal voice and/or data communicators. Low-complexity communicators can provide many hours of “talk time” or data transmission time and perhaps several days of standby time from small batteries (≤ 1.5 oz). Because this application of wireless loop technology can reduce the inherent costs in several parts of a wireline loop, it has the potential to provide convenient widespread PCS at less costs than providing telephone services over conventional wireline loops. This low-power wireless loop application does not fit into any existing communications system paradigm. Wireless technology with tetherless access and wide-ranging mobility, e.g., the personal access communications system (PACS), does not fit the accumulated wisdom of the wireline telephony paradigm. It also does not fit the paradigm of existing cellular radio that has sparsely distributed expensive cell sites, and it is not targeted at fixed video services as is wireless cable. Because a significant change in thinking is required in addressing this new low-power low-complexity widespread wireless loop paradigm, its large economic advantages and service benefits have not yet been embraced by many of the existing communications providers, who appear to be more comfortable pursuing the better-known paradigms of video using wireless cable, or of cellular radio in the guise of high-tier PCS, or in the guise of rapid economical deployment of telephone services in developing nations. This paper discusses the inherent economic advantages and service benefits of low-power low-complexity wireless loop technology integrated with network intelligence aimed at providing economical low-tier PCS to everyone.     

The Broadband Access Facility

The deployment of broadband access networks will revolutionise many aspects of society in the early years of the next millennium. Manufacturers, telecommunications providers and cable television operators world-wide are investing heavily on research into networks that provide broadband multimedia services to customers. BT has developed a prototype of a full service access network that can connect customers via optical fibre, digital subscriber line or radio technologies. This paper describes the physical implementation of the prototype network and the wide range of services that it can support.This prototype network, referred to as the 'broadband access facility' is enabling BT and its partners to understand the best access architectures for a given environment through practical testing. The network now serves as an experimental platform, that can be used for communicating broadband concepts, designing operational processes, developing management solutions and testing advanced applications.The full service access networks (FSAN) initiative is a collaboration involving fourteen of the world's leading telecommunications network operators and major equipment manufacturers. Its vision is to create a shared requirements specification for access systems supporting narrowband and broadband services. This common specification will mean that broadband network components can be developed for world markets, thus raising volumes and driving down unit costs. The common system specification is based around an ATM/SDH (asynchronous transfer mode/synchronous digital hierarchy) core network, with local optical fibre distribution via an ATM PON (passive optical network). DSL (digital subscriber line) systems maximise reuse of existing copper plant. The exact DSL system used depends upon where the optical system is terminated, e.g. in the local exchange, cabinet, kerb or home. Hence this broadband access system can support a range of access architectures — this flexibility is fundamental to the consensus achieved in FSAN.     

Technology 1991: telecommunications

Noteworthy trends and occurrences in telecommunication during 1990 are examined. half a dozen countries deregulated their telephone companies to admit competition in the hopes of accelerating technological development. One of the leading technologies to take off was mobile communications, particularly services based on digital transmission. A worldwide standard for the broadband integrated-services digital network (ISDN) was finally accepted, allowing worldwide compatibility for the emerging fiber-optics-based broadband ISDN systems. Meanwhile, narrowband ISDN crossed international borders for the first time, offering transoceanic service. In optical-fiber transmission, the most promising development was erbium-doped optical amplifiers, which are cheaper and simpler for long-distance communications, especially if many signals are to be multiplexed onto one fiber. In addition, investigators demonstrated a simple processor entirely based on optical logic elements and parallel optical connections through free space, which may be another significant step toward an optical computer