ISSN:1124-318X    

DOI:10.1002/ett.4460020103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:1124-318X    

DOI:10.1002/ett.4460020104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractMultimedia communications is the field referring to the representation, storage, retrieval and dissemination of machine‐processable information expressed in multiple media, such as text, voice, graphics, image, audio and video. With the advent of high capacity storage devices powerful and yet economical computer workstations and high‐speed integrated services digital networks providing a variety of multimedia communications services are becoming not only technically but also economically feasible. Applications in medicine, education, travel, real‐estate, banking, insurance, administration and publishing and advertising are emerging at a fast pace. These applications are characterized by large multimedia documents that have to be communicated within very short delays. Computer‐controlled cooperative work, whereby a group of users can jointly view, create, edit and discuss multimedia documents is going to be characteristic of many transactions in the year 2000. In this paper, we review the activity in Multimedia Communications, Services and Appli

ISSN:1124-318X    

DOI:10.1002/ett.4460020105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe paper is presenting a sketch of the main results achieved in the recent years and of the ongoing activities (mainly within the Standardization Bodies) in the areas of audio and video coding for bandwidth reduction. The evolution of the telecommunication Field and the needs which originate the different standards are also considered.The paper is organized in two main chapters: the first one is dealing with the techniques for audio and speech coding while the second presents the main achievements in terms of Recommendations and consolidate algorithms for image coding. Concerning speech and audio coding the paper presents and overview of the coding techniques and then examines the different environments of transmissions (network and mobile communication), the bandwidths required to satisfy the considered applications and the defined speech quality evaluation methods. A similar approach has been used for video coding and the evolution of the coding techniques appearing in the CCITT Recommendations is presented. The ongoing activities within CCIR, CMIT, CCITT and ISO towards new worldwide standards are also outlined providing indications on the areas which will require further developments.

ISSN:1124-318X    

DOI:10.1002/ett.4460020106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper deals with the deployment of the narrowband Integrated Services Digital Network, which is conceived as a significant rationalization of the existing public telecommunication networks, which include at present a number of different structures devoted to the various kinds of services.The main guidelines of ISDN evolution are depicted, starting with a short analysis of the expected wide range of TLC services, as this market is the main driving force for the deployment of new network architectures providing a powerful integrated access, a rapid service introduction and a high flexibility. The resulting reference network architecture is then described, highlighting the maximum possible integration of techniques and services, the unified access for the whole range of TLC services, the significant improvement of the user‐network signalling capabilities, the provision of high level network capabilities and the efficient communication among the various network entities. Some interworking and network dimensioning aspects, related to the gradual deployment of this new network architecture, are also examined, together with some consideration about further evolutionary steps.A second part of the paper is devoted to an analysis of ISDN functionalities, starting with a short survey of ISDN protocols (X.31 network access protocol, higher layers protocols, CCITT N. 7 network signalling for ISDN), which are the international standards on which this evolution is based. Circuit and packet ISDN switching facilities are then briefly examined, focusing on ISDN access functions, which are very important for both the access integration and the hardware cost reduction. A further important point examined concerns ISDN protocol testing and validation (for both terminals and switching offices), together with the performance evaluation of ISDN switching officies.The last part of the paper is devoted to a short survey of the present status of ISDN world development (pilot services, start of commercial services), starting from the European situation (France, Germany, United Kingdom, Italy etc.), examining the ISDN development in other Countries (United States, Japan, Canada and others) and giving finally some indications about the expected future plan

ISSN:1124-318X    

DOI:10.1002/ett.4460020107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper deals with the final goal of the evolutionary process of the public telecommunication networks towards broadband capabilities (B‐ISDN), process which is based on the adoption of the Asynchronous Transfer Mode (ATM).At first, a critical analysis is carried out about the transfer modes which gave rise to the definition of ATM. This analysis makes reference to three different and complementary aspects, i.e. the multiplexing technique, the switching principle and the protocol architecture.Then the current status of B‐ISDN is presented on the basis of the most recent results available from the standardization activity. In particular aichitectural aspects and traffic control issues are conside

ISSN:1124-318X    

DOI:10.1002/ett.4460020108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral generations of switching systems for broadband networks have been developed in the eighties. This paper describes the structures, the properties and performance Of the first generation of such systems known as banyan interconnection networks. Three classes of these networks are examined, that is unbuffered networks, buffered networks with internal queueing and buffered networks with output quequeing.

ISSN:1124-318X    

DOI:10.1002/ett.4460020109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper traces the evolution of LANs ad MANs from the early Ethernet days to recent Gigabit per second prototypes. Three generation are identified. The first generation includes Ethernets, Token Rings and Token Busses, and has a speed upper limit in the order of lOMbit/s. The second generation consists of architectures which have evolved from the first generation exploiting the fiber optics technology and properly modifying the access protocols. Higher speeds (in the order of hundreds of Mbit/s) and larger distances are thus achieved. Typical examples are FDDI and DQDB. The third generation represents a further step in the direction of higher speeds (hundreds of Gigabit per second). The key elements to achieve such high speeds are passive optic components and wavelength division.The paper consists of two parts. In the first part, the evolution of topologies and access protocols from generation to generation is described. In the second part, two representative examples of third generation networks, namely, Tree Net and WON, are presented.

ISSN:1124-318X    

DOI:10.1002/ett.4460020110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractConsumer and business demands for cellular mobile telephones and residential cordless phones are growing rapidly throughout the world. Both are relatively new and still function with their original, first generation technologies. In response to various pressures second generation systems and services are scheduled for introduction over the next three years. Meanwhile researches are formulating a vision of the third generation, when cordless, cellular, and other wireless networks will merge in a unified means of wireless access to advanced information services.This paper traces the evolution of wireless information networks by examining goals, network architecture, transmission technologies, and control channels. In each instance, we describe, in a general way, first generation systems. We then discuss details of four different second generation systems: Pan‐European Digital Cellular (GSM), North American Digital Cellular (IS‐54), Second Generation Cordless Telecommunications (CT2), and Digital European Cordless Telecommunications (DECT). Finally, we provide a glimpse into the future by presenting work in progress on third generation technology, based on packet transmission and switch

ISSN:1124-318X    

DOI:10.1002/ett.4460020111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractOperating telecommunication networks and services economically, reliably, and efficiently has been the major goal for every Administration and Operating Company since the very beginning of telecommunication systems. As soon as computers became available, applications aimed at increasing levels of efficiency and reducing the cost of operations were developed by mechanizing a number of commercial and administrative procedures as well as operations, such as billing, service order management, archive conversion to data files, etc.More recently, the introduction of more advanced network equipment (with increasing intelligence capacity), together with the availability of computers and peripherals providing attractive cost‐to‐performance ratios, has led to the development of systems designed to centralize and mechanize a variety of network operations and management activities. To date, the growth in the number of these two classes of support systems has been,instance‐driven, as they have been thevertical and dedicatedresponses to specific needs generated in individual sectors of the company organizations.Today, a number of new factors are strongly and urgently leading towards the evolution of the Operations Support Systems (OSS). In fact, while telecommunications networks are dramatically evolving in terms of technological levels or complexity, there is an even more rapidly increasing demand for high quality custom‐tailored services.The integration of support systems to meet the progressive integration of networks and services has therefore become essential in order to meet customer needs quickly and flexibly, adjust to the company's organization without major overhauls, reduce operation costs and ensure the desired quality levels so as to maintain or stay on the leading edge of technology.The evolution towarddata‐drivenarchitectures for the operations support systems is certainly not an easy task, made still more difficult by the requirement of preserving the existing systems, as much as possible, for both operational and economic reasons. Therefore, having defined the integrated OSS target by a top down approach, the practical way adopted to accomplish the integration process must follow a bottom‐up approach where the present reality is taken into account with the possible and predictable evolution. Naturally, one must also consider the trade‐offs between investments and derived benefits.This approach, aimed at progressively interconnected OSSs, will minimize the investments, by taking the maximum advantage out of them, and should allow a fine, progressive tuning of the Operating Company needs. The interconnectivity issues may be satisfied by the overlay of a new network, the Telecommunication Management Network ‐ TMN ‐, onto the Telecommunication Network. In this subject, the efforts of the International Standard Organizations are concentrated on the definition of the interfaces and communication protocols between the Network ElementS (NE) in the Telecommunication Network and the Operations Systems (Os) in the TMN. The implementation of an overlayed TMN is the only viable approach for the short ‐ medium term, but new architectures may become possible as switching systems evolve. In the long term, we may come to a point where these two networks, the support TMN and the telecom network, collapse into a single Information Network. However, the medium term evolution of the TMN networks, as it is suggested by the worldevolution, could be nothing else but a completion of the ideas of integration for the current systems. In the 92‐96 we will witness the application of the standards being approved or studied today.In a more distant future, new architectures will become available for telecommunication systems providing higher levels of flexibility, high speed links and high capacity distributed data bases.The ability of operations support functions to keep pace with the high speed, software based, environments of the future in an automated fashion, may be enhanced by new system technologies both in software concepts and in hardware constructs. For example, the structured, process oriented, datadriven, open system architecture should provide the flexibility to adjust to the dynamics of high speed networks and to the rapid introduction of software services developed by the Operating Companies. This structured approach should minimize the distruptions to the overall, complex, integrated, automated operations support functions while maintaining, without human interventions, maximum automated flow‐through of the functions. It should also enhance the ability of evolving to new software design concepts such as knowledge engineering.A look at the picture of future computing systems indicates that the movement of parallel processing techniques from academy to business applications, the increasing capabilities of database machines, and the advancing neural‐network horizons for expert systems engines, will all be active pursuits into the twenty‐first century. Flexible and Open Systems Architectures will enhance the Operating Company capabilities to economically adopt these emerging software and hardware developments.This paper addesses first some general concepts on OSS, the features of the present situation, with particular reference to Italy, and the rationale behind the present pressure for interconnecting and integrating the OSSs. How to identify the evolutive steps towards this integration and how to support the progressive implementation of the TMN is then discussed, together with the status and the perspectives of the standardization studies in progress in many European and International Bodies. Even if the attention is focused on the predictable evolution within the next decade, a quick look at the following years is also given, trying to discuss the possibility that the two networks, the support TMN and the telecom network, collapse into a

ISSN:1124-318X    

DOI:10.1002/ett.4460020112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY