Marco Mercinelli, Pier Luigi Emiliani, Constantine Stephanidis and Gunnar Hellström
Introduction
This chapter aims at providing the reader with a forecast of the likely scenarios and of the evolving trends for telecommunications networks and services from now to the beginning of the next century. This material can be used as a technological framework related to accessibility problems, potential solutions and new communication services for disabled and elderly people.
General Telecommunications Trends
The developments in the telecommunications industry will have a major impact on every aspect of European society (Luvison, 1994). The boundaries between tele-communications, information technology and enter-tainment industries will blur as digital technology dominates and information services grow. Public Network Operators (PNO) will be involved in the collection, management, processing and storage of information, not just in its transportation.
Multimedia applications will become a major driving force (see chapter 5.2). The residential market will provide significant opportunities for new and growing revenues. Mass market demand for teleworking, entertainment and information services will drive broadband networking on a pan European scale, to add to the earlier broadband business growth.
Provision of a complete portfolio of services will be available from independent agents or public networks operators. Customers will demand access to their own range of services independent of country and network operator's boundaries, resulting in the separation of services and network infrastructure. Service indepen-dent network platforms will develop built upon a consistent network architecture. Mobility in terms of both personal and terminal mobility will be offered on a pan-European basis.
A pan-European telecommunications infrastructure will allow the delivery of the same service with the same characteristics (quality, reliability, interfaces, etc.) all over Europe, irrespective of the end user location. It is the result of a process of interworking and integration building on the individual national networks.
The adoption of standard equipment and operation procedures (protocols) from ETSI (European Telecom-munications Standards Institute) and ITU (International Telecommunication Union) will bring the networks of the different countries to an equivalent level, through parallel independent evolution. The significant driving forces for this process are the agreed common requirements on network performance (reliability, availability, etc.) and the requests from the end users who have become increasingly aware of the advantages arising from modern telecommunications services. In parallel a voluntary harmonization process will take place, ranging from bilateral agreements to multilateral memoranda of understandings, such as on the Managed European TRAnsmission Network (METRAN) and the European Asynchronous Transfer Mode (ATM) pilot network.
The Functional Impact of Digital Networks
From a functional point of view, the first effect of the evolution of digital networks and the corresponding use of a digital representation of signals is the improvement in the quality of transmitted information. Problems with conventional telephony are well known. Voice is of low quality in principle, due to the narrow bandwidth. Moreover, different sources of noise may corrupt the transmitted signal. Fading can reduce the level of received signals. Interferences are possible leading to loss of quality and privacy in communication as well. Due to their representation in terms of only two symbols, which correspond to the possible values of a binary digit, digital signals are inherently much more robust to the effects of noise and other disturbances than their analogue counterparts.
Finally, it has to be considered that the use of a digital representation of signals allows an easy combination of different information components (speech, audio, data, pictures and images) in a single communication session. All these components are represented as sequences of numbers and can be used in a synergetic way to set up suitable communication services and applications. This is fostering the emergence of multimedia services and applications, which could have an important impact on the disability sector (Ackland, 1993; Aravind 1993; Milt, 1992).
The use of digital signals has an additional important consequence. There is a substantial convergence between communication technology and computer technology. Switching systems, advanced terminal equipment, network and service management systems are all basically computer systems. This has two main implications:
The possibility of mixing different information com-ponents and embedding intelligence in all stages of deployment of communication technology is creating very interesting opportunities for new services and applications (e.g. multimedia services and applications, "intelligence" in terminals, services and applications).
In principle, it is possible to transmit digital signals through a digital network conserving the original quality. The contents of a compact disk, for example, can be transmitted conserving its original high fidelity characteristics entirely. Obviously this is only true in principle, for two main reasons:
For example, standards and corresponding integrated circuits (codecs) exist for compression of digitized speech using 32 kbit/s and 16 kbit/s. The JPEG (Joint Photographic Experts Group) algorithms for still images compression provide good image quality at compression factors of 10 to 20. For moving video, algorithms exist, e.g. MPEG (Moving Pictures Experts Group), for transmission rates of Mx384 kbit/s with M from 1 to 5 and Px64 kbit/s with P from 1 to 30, and with different possible trade-offs between quality and bit rate (transmission cost).
Intelligence in Networks
As described in the previous paragraph, the evolution of telecommunications networks and equipment is moving towards the use of digital circuitry and information technology concepts and products, which involve the increased use of network elements that are controlled by software, the sharing of data, the distribution of application processing and the definition of standard interfaces between network elements. This evolution is meant to comply with user demand for more sophisti-cated services and their rapid delivery, leading to a new concept of network and services management and to the introduction of Intelligent Network (IN) facilities. (Doyle, 1992; Chen, 1993; Fujioka, 1993).
A standardization procedure has begun to allow a harmonized world-wide introduction of the corresponding facilities (Garrahan, 1993), aiming towards applying the IN concepts to all telecommunications networks, (e.g. Public Switched Telephone Network (PSTN), narrow-band and broadband ISDN, packet-switching public data networks, and mobile networks).
The main fields of impact of the foreseen recommen-dations are in the areas of: service creation, service management, service interaction, network management and service processing. The activities are presently mainly concerned with routing, charging and user interaction problems.
Some examples of the type of services, made possible by the first recommendations are the UPT (Universal Personal Telephone - the subscriber is able to use telecommunications on the basis of a personal number assigned to him, which is applicable across multiple networks at any access network) and the VPN (Virtual Private Network - public network resources are used to provide the user with private network capabilities, such as private numbering plans and dialling restrictions). The first service is essentially based on the capability of access in real-time to distributed data-bases, where the profile of the users is available (even if obviously with severe confidentiality constraints). The second is taking advantage of the distributed software control of the network structure.
A detailed description of the situation throughout Europe and worldwide is available in literature (Motiwalla, 1992, Mossotto, 1992, Cancer, 1993, Suzuki, 1992, Russo, 1993).
At the present state of development, the IN architecture is confined to basic telephony call-control capabilities and is based on a set of interfaces and protocols which could clearly separate the switching from the service aspect of the network, so that the application developers have only a logical view of the network control functions.
The evolution towards a general information network would provide the customers with the facilities of on-demand access and management of information any time, in any volume and in any form. This involves an architecture that enables flexible construction of services, which are composed of service components distributed over a geographically disperse and techno-logically heterogeneous network.
Finally, most of the new possibilities expected in telecommunications services and applications are connected to the evolution of connectivity, between different networks and subnetworks, and between the networks and the end users.
The evolution will probably lean towards integration of each wide area communication technology, including fibers, satellites, and microwaves, to construct the backbone of the information highway, while users will be connected through fibers, coaxial cable, copper and wireless, according to their communication needs (see chapter 5.1 on Information Highways). Data servers will be computers (from supercomputers to microcomputers), while network clients will be disparate (e.g. palmtop computers (PCS and Personal Digital Assistants (PDA), smart phones, advanced TV set). Network software will include operating systems, network protocols and services, user interfaces, databases and so on. As a result, the new infrastructure will probably emerge as an integration of different communication systems and technologies, with variable resources which will be made available to the users according to their communication needs.
In terms of protocols, the emerging alternative to TCP/IP used in Internet and in the UNIX environment is ATM which resolves some of the difficulties of TCP/IP in real time use. One possible alternative is to run TCP/IP over ATM.
Services on the Digital Intelligent Network
The emergence of the digital intelligent network will cause the emergence of new services and/or the increase of functionality of already available services and corresponding applications. The basic (i.e. stand alone) communication services provided by the network are at the moment the following: Telephony, Teletext, Telefax 4, Mixed mode (teletext and telefax 4), Videotex and Telex.
There are a number of supplementary services (based on the basic communication services) under study by ITU (Formerly CCITT):
New Terminals
Some of this new services could require new terminal facilities such as displays, soft keys, card readers (e.g. smart phones), that could potentially create accessibility problems to disabled and elderly people.
Concurrently with the evolution of the network, services and applications, a parallel development of new terminal equipment is under way. This trend of development is expected to continue in the near future due to many factors. Some of these include:
The above factors allow the implementation of a variety of new terminals, ranging from complex multimedia workstations to small portable telephone equipment (Sheng, 1992; Sakata, 1993; Adam, 1993; Levinson, 1993; Roe, 1993; Jager, 1993; Benimhoff, 1993; Steele, 1993).
Many futuristic phones for ISDN have been shown, featuring voice telephony combined with functions such as: visual call control, drawing pad for "telewriting", text mail handling, number catalogues, incoming number display, black list of undesirable incoming numbers, data path for PC connection.
Moreover terminals and products for ISDN connections have emerged and are becoming dominant in the ISDN area:
Other systems appearing as ISDN terminals, but still not representing any big markets are:
In the disability area, the following systems are of special interest:
The above considered developments are also boosting the emergence of mobile communications systems and services, as described in chapter 4.4.
Conclusions
Telecommunications network and services are determining factors for social development and economic growth. The driving forces for this process are the agreed common requirements on network performance. Customers may vary over a wide range in their needs and preferences. Different categories of customers will be satisfied by well designed and tailor-made services with personalized parameters through common friendly interfaces.
Network Architecture: Scenario 1995
Improvement of the existing narrowband networks (PSTN, ISDN and data networks) and a first provision of early broadband facilities Metropolitan Area Network (MAN), and first generation of ATM cross-connections):
Network Architecture: Scenario 1997
Strengthening of ISDN infrastructure in terms of access spreading, nodes and services (e.g. provision of new services like switched virtual circuit frame relay and Nx64 kbit/s). An overlay pan-European B-ISDN (Broadband ISDN infra-structure will mainly provide high speed interconnection network to business users handling traffic with aggregated bit rate exceeding 2 Mbit/s. The following developments are expected:
Network Architectures: Scenario 2000 - 2005
A decisive spreading of the B-ISDN and full exploitation of ISDN features are expected in this long-term evolu-tionary scenario:
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