tched Networks lakovos Venieris
he ultimate aim of telecommunications is simply to enable human beings to communicate over long distances. In a physical meeting, humans make free use of several media in a conversation (e.g., voice, prepared text or graphics, gestures, or sketches on a whiteboard). Moreover, there is a whole range of conversation styles, from two-party talks to lectures for a large audience. Telecommunications services currently do not really support this natural way of communicating. Most telecommunications today is carried out over separated media (telephone, fax, e-mail) in a two-party configuration. There are already good implementations of more advanced communications facilities which integrate multiple media and enable multiparty conversation. However, due to limitations of network infrastructure, such applications can actually be used only in the context of local area networks, not for communication over wide distances. Network support for more advanced, and therefore more natural, ways of communicating is the topic of the articles presented in this feature topic. Broadband networks based on ATM technology provide an adequate technological basis for true multimedia telecommunication. ATM provides high bandwidth and supports individual assignment of quality of service (QoS) to connections carrying specific media, including true real-time communication (e.g., for voice and video). However, the currently available widearea ATM infrastructure can be seen as only the first generation in an evolutionary development toward support for multimedia communications. Currently, ATM wide area networks are mainly used for permanent virtual connections which are stable over a relatively long period of time and often carry a mixture of diverse traffic, thus not making full use of the potential of ATM technology. The second generation in ATM network evolution adds switched virtual connections which are set up on demand using a signaling protocol, so applications can use individual connections with exactly defined QoS properties. However, the current standards for ATM signaling do not cover any specific support for multiparty communication (e.g., conferencing). Moreover, ATM signaling is not yet able to coordinate several bearer connections which belong to a single service instance, a feature essential for such things as adequate billing for multimedia communications. The topic addressed in the following articles is therefore the third generation of wide-area ATM infrastructure, which will offer additional functionality to make the networks ready for true multimedia communications. The key issue here is that a higher level of intelligence is required from the network, providing, for example, the management of complex communication sessions with multiple parties and multiple bearer connections. In this feature topic, three closely interrelated articles investigate the range of technical options which have been proposed by recent research projects for such third-generation networks.
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Heinrich Hussmann
Strong emphasis is put in all three contributions on an evolution path which starts from current telecommunication standards but is also open to further long-term development toward new architectures such as the TINA architecture. The intelligent network (IN) concept is a well-known architecture aimed at rapid introduction of innovative services. The ITU-T has already built a powerful concept for multiparty calls into the recent Capability Set 2 of the IN architecture. It is promising to extend this architecture toward broadband networks and multiconnection sessions, as investigated by EURESCOM project P506. Therefore, the first article of this feature topic, by M. O'Reilly Roche, presents the concept of Connection View states,which are used to support multiparty services in the most recent IN standards, and discusses the evolution of these concepts toward broadband networks. The second article, by G. Prezerakos, S. Salsano, A. van der Vekens, and F. Zizza, proposes a more drastic deviation from IN standards and provides a true object-oriented approach to multimedia service sessions. Nevertheless, the architecture is carefully designed for compatibility with existing IN standards. This article also reports on an impressive international trial demonstrating the practical viability of intelligent broadband networks which was carried out by the international project INSIGNIA in the framework of the European ACTS research program. Compared to this rather evolutionary approach, the TINA Consortium has proposed a long-term-oriented perspective for future telecommunication services based solely on a communication mechanism for distributed software objects. The third article, by M. Listanti and S. Salsano, treats the issue of how a migration from intelligent broadband networks toward a future TINA architecture may be achieved. Together, the three articles provide a compact overview of the current state of discussion on network intelligence for broadband multimedia services not easily found anywhere else.
BIOGRAPHIES IAKOVOSVENIERIS [MI (
[email protected]) receiveda Dipl.-lng. degreefrom the University of Patras and a Ph.D. degree from the National Technical University of Athens (NTUA), all in electrical and computer engineering. He is currently an assistant professor in the Electrical and Computer Engineering Department of NTUA. He has participated in several European Union and national projects dealing with B-ISDN protocols, intelligent networks, and ATM switching and access techniques. He is a member of the Technical Chamber of Greece. Heinrich Hussmann [MI (
[email protected]) received a Diploma degree in computer science from theTechnical Universityof Munich and a doctoral degree from theUniversityofPassau. From 1994to 1997, hewasa researcherforsiemens Public Communication Networks, until he became a professor of computer science at Dresden University o f Technology. He has taken part in several international European research projects dealing with software technology and communication networks. He is a member of ACM.
IEEE Communications Magazine June 1998
