NETWORKED VIRTUAL ENVIRONMENTS
lgor 5. Pandric
he concept of the next-generation network is guided by a vision of a multiservice, multi-access network of networks, providing a number of advanced services anywhere, anytime. As demonstrated in South Korea, t h e leading country in providing broadband Internet access (see the December 2003 issue), new services have indeed driven tremendous market growth. With the ever increasing demand for new services and applications, networked virtual environments (NVEs) may he considered yet another advanced service, in the merging of multimedia computing and communication technologies. NVEs allow multiple users to experience 3 D computer-generated virtual worlds over the network. A wide range of exciting NVE applications may b e foreseen, ranging from virtual shopping and entertainment (especially games and virtual communities), to medicine, collaborative design, architecture, and education/training. O n e of the main problems in the area of NVEs is to adequately meet t h e communication requirements for complex multimedia and/or virtual reality presentation, multiple senders and receivers, as welias perceived realtime interactivity. This becomes a decisive issue when it comes to evaluating the quality of service (QoS) perceived by the user. T h e problem is that the user perception of QoS, a s o p p o s e d t o t h a t of t h e network, is typically expressed in subjective and qualitative rather than objective and quantitative terms. This calls for a complementary approach in how application and networking requirements are addressed, since an NVE application may require that both the network and the application specifically address, and adapt to, each other’s capabilities and preferences. In other words, in addition to network-aware applications, we need application-aware networking. In this Feature Topic we present four articles that illustrate some of the above problems and solutions in the field of NVEs and QoS for NVE applications from the communications point of view. One of the most popular groups of NVEs are collaborative virtual environments (CVEs), which enable multiple users’ collaboration. In the first article, J o s h , DiGiacomo, and Magnenat-Thalmann give a concise review of the history of CVEs and present the related recent additions to
the MPEG-4 standard, to the development of which their group also contributed. They describe the key issues common to all CVE systems: network topology for CVE communication, dead reckoning, area of interest management, scene segmentation, and compression. Finally, they discuss and evaluate the parts of the MPEG-4 standard related to supporting CVEs. The second article, by E. Frecon of SICS, presents the Distributed Interactive Virtual Environment (DIVE), one of the most prominent and mature NVEs developed within t h e academic world. Started in 1991, D I V E has evolved into a generic architecture to support various multi-user CVE applications over the Internet. The article focuses on the communication and programming aspects of DIVE. In terms of communication, three key issues include localization, scalability, and persistence. T h e final two articles address QoS. As already mentioned, QoS may be observed at various layers of the communication architecture. T h e third article, authored by Gracanin, Zhou, and DaSilva of Virginia Tech, addresses QoS for NVEs by proposing a three-level QoS architecture, where the three levels represent user, application, and network, respectively. They describe an approach for QoS mapping between adjacent layers that allows reduction of the network requirements for a given user-level QoS value. The applicability of t h e proposed approach is demonstrated on an (appropriately modified) DIVE system. T h e last article, by Skorin-Kapov, Mikic, Vilendecic, and Huljenic, focuses on the network-level QoS requirements of NVEs observed within the framework defined by t h e Third Generation Partnership Project (3GPP). They p r o p o s e a classification a n d m a p p i n g of networking requirements to standard Universal Mobile Telecommunications System (UMTS) QoS classes and illustrate the proposed mapping by using several prototype applications in an emulated network environment. T h e idea for this Feature Topic began with the Special Session on NVEs at the 7th ConTEL, International Conference on Telecommunications, held on 11-13 June, 2003 in Zagreb, Croatia. T h e conference was technically co-
IEEE Communications Magazine
sponsored by IEEE Region 8 and the IEEE Communications Society. The Special Session o n N V E s consisted of six technical papers selected from 12 submissions, and the keynote address was given by Michael Zyda of the Modeling, V i r t u a l Environments, and Simulation ( M O V E S ) Institute. We thank the authors who submitted articles for this issue, and the reviewers f o r providing constructive and timely feedback. Finally, our thanks go t o the IEEE Communications Maguzine staff for helping us manage this Feature Topic. Enjoy the issue.
BIOGRAPHIES MAJAMATIIASEVIC IMI ([email protected]
) received her Dipl.-lng. (1990). M.Sc. (1994). and Ph.D. (1998) degrees in electrical engineering from the University of Zagreb, Croatia. and an M.Sc. in computer engineering (1997) from the University of Louisiana, Lafayette. She is presently an assistant Proferror in the Department of Telecommunications, Faculty of Electrical Engineering and Computing, University of Zagreb. Croatia She was a research associate in the Virtual Reality and Multimedia Laboratory Of the A 4 M Center at the University of Louisiana at Lafayette from August 1996 t o April 1999, and a visiting researcher a t the Technical University of Graz. Austria. on several OCCasioni between 1992 and 1996. Her main research interests include networked virtual environments and advanced multimedia Services for next-generation networks. She has been involved in organiring several conferencer. sewing as Program, Registration, and Publicity Chair. She is a member of IEEE Communications. Computer, and Con-
trol Systems Societies, ACM, and Upsilon Pi Epsilon Honor Society i n the Computing Sciences. IGOR S . PANDZIC ( i g ~ ~ . p ~ " d ~ i ~ @isf ean~ assistant .h~) professor in the Department of Telecommunications. Faculty of Electrical Engineering and Computing, University of Zagreb. Croatia Formerly he worked as a senior assiStant at MIRALab, University of Geneva. Switzerland. where he obtained his Ph.0. in 1998. The same year he worked as a visiting Scientist at AT&T Labs, United Stater. In 2001-2002 h e was a visiting scientist in the Image Coding Group at the University of Linkoping. Sweden. Hi6 research interexts are i n the field of computer graphics and virtual environments. They focus an virtual characters. and include networked collaborative virtual environments, facial analysis and synthesis. computer-generated film production. and parallel computing. He has published t w o books and around 50 papers on these topics. He was one of the key contributors t o the Facial Animation specification in the MPEG-4 International Standard for which he received an I S 0 Certificate of Appreciation in 2000. He is involved in undergraduate and postgraduate teaching activities at Zagreb University. He has held various positions in organizing numerous international conferences. ALGIRDASPAKSTAS ISM] ([email protected]
) received his M.SC. in radio-
physics and electronics from lrkutsk State University. and his Ph.D. in ryrt e m i programming from t h e Institute of Control Sciences. Currently he is with London Metropolitan Univeriity. Department of Computing, Cammunicationr Technology and Mathematics. where he is doing research i n the area of communications roftware engineering and is teaching courses i n network planning and management, and computer systems and networks. He is active in the IEEE Communicationr Society Technical Committees on Communications Software. Multimedia Communications. and Enterprise Networking. He has published 3 rerearch monographs ( 2 authored and 1 edited) and more than 120 other publications. He is a member of the ACM and the New York Academy of Sciences. He is currently a member of the Editorial Boards of IEEE Communicationr Magazine. Cyberneticr and Systems Analysis. and Journal o f Information and Organizational Sciences.
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