COST 264

For the implementation of a European Concerted Research Action designated as COST Action 264 Title : Enabling Networked Multimedia Group Communication The Signatories of this Memorandum of Understanding, declaring their common intention to participate in the Concerted Action referred to above and described in the Technical Annex to the Memorandum, have reached the following understanding :
  1. The Action will be carried out in accordance with the provisions of the document COST/400/94 _Rules and Procedures for Implementing COST Actions", the contents of which the Signatories are fully aware of.
  2. The main objectives of the action are to enable the cooperation of scientists in Europe involved in the design of the architecture and applications related to group communication. Results will be made available to the signatories as well as to the industry. Also, contributions will be send to standardization bodies. Another primary goal will be to experiment solutions and applications on a Mbone type of network and provide recommendations on how such a network can be enhanced.
  3. To this end a cooperative effort involving universities as well as telecommunication R&D establishments and industries is required.
  4. The overall cost of the activities carried out under the Action has been estimated, on the basis of information available during the planning of the Action, at 5.75 MEcus at 1997 prices.
  5. The Memorandum of Understanding will take effect on being signed by at least five Signatories.
  6. The Memorandum of Understanding will remain in force for a period of 4 years, unless the duration of the Action is modified according to the provisions of Chapter 6 of the document referred to in Point 1 above.

COST Action 264

Enabling Networked Multimedia Group Communication

A) Background

The work carried out within various projects including COST237 has demonstrated the importance of multimedia group communication for enabling high-performance networking and new emerging applications. One can mention multiparty conferencing, Internet telephony, collaborative work or distributed interactive simulation. They are characterized by interactivity, real-time constraints, and various number of participants. Obviously, all these applications require multipeer functionalities that are not currently available as a basic service. It has been recognized that providing both multipeer capabilities as well as quality of service in various forms is not achieved no matter what technology is considered, i.e : ATM, IP, mobile networks, satellites, etc. Moreover, it was shown that there is a lack of practical understanding and experience in this area, mainly because no experimental network is available in Europe. The only existing infrastructure is the experimental Mbone (overlay multicast network on the Internet) ; but it is not satisfactory as it does not provide any transmission control facility (congestion/flow control, reliability, Quality of Service, group and address management, etc.). Nowadays, there exists an increasing demand and a large potential market for multimedia multipeer applications that justify the development of an efficient European multicast network infrastructure.

The objective of this action is to build up on the COST 237 results (Multimedia Telecommunications Services) to bring together European research teams involved in group communication both from the infrastructure and application perspective. They will cooperate in order to identify solutions for the improvement of the multipeer communication architecture, including application, communication mechanisms, and infrastructure. This area is becoming of utmost strategic importance both from the research and industrial perspective. An incredible amount of work is done in this domain in the USA and Japan. Some work is also visible in Europe but with a lack of coordination and dissemination of results to the academic and industrial world. This is enforced by the need of experimentation on a multicast network to develop and assess solutions.

B) Objectives and benefits

The main objective of this action will be to provide a forum where researchers and industrials active in this area will participate. Complementary experimentations will be conducted to enable and understand multimedia group communications that will be available on various networks in the future. These activities will contribute to leverage European research in this domain as well as to the development of enhanced architectures at the International level.

The action will be divided into two complementary parts of similar importance, that together will enable the action to meet its goals :

The " infrastructure and dissemination " part aims at cooperation and coordination between research actors to improve the existing infrastructure to support group communication (principally the Mbone). The infrastructure activity is a pre-requisite to the scientific cooperation. It will allow experimentation with the applications and mechanisms developed by participants, as well as providing a way to support an effective dissemination of the work. This activity will: The " research and experimentation " part is devoted to cooperation between participants in the areas of multicast, multipeer, group communication and relevant applications. This is an area of utmost and strategic importance for research and industry. Multimedia group communication will leverage industry competitivity and provide new tools for cooperative work. This activity will: Both activities are tightly coupled and converge to :

A technical report that describes the progress made in the area of group communication thanks to the action activity. This report will be published as a book or as a special issue of a technical journal .

Benefits, as described above, will be an understanding of the issues to enable group communication that appears as a challenging research area as well as an emerging market. It will organize the research community involved in these areas and disseminate the results outside the action participants (academic and industry). Finally, the action should have an influence on the standardization activities in this domain. Recommendations on how to use the results achieved in the action and solutions to enhance the Mbone will be provided.

According to the issues mentioned above, the action will deliver and emphasize on the following results :

C) Technical program

The action will enable a strong and permanent cooperation and coordination between the actors from different perspectives, mainly technical but also through experimentations that are of utmost importance when group communication is involved. The action goals are on one hand to identify the problems encountered with group communication (and propose solutions to these problems), and on the other hand to make a " well-behaved " multicast backbone comes true to support experiments, allow fast and easy dissemination of results and support tele-collaboration.

C.1. Research and experimentation

Group communication is recognized as a new paradigm that requires a deep modification of the networking functions, mechanisms and protocols designed with only " unicast " communication in mind. The action participants are already involved in this research. The following are currently addressed :

Naming and addressing.
In the current Internet, multicast address allocation is done on a random basis. With group communication becoming popular, and applications using more than one group per session, it becomes urgent to define hierarchical address allocation schemes together with a unified naming strategy. Both will improve error control and congestion control by providing a simple and efficient way to select multicast addresses and to identify objects within a data flow.

Error control.
Today, there are three main approaches to error control in multicast: local recovery, hierarchical recovery, and FEC. These three approaches are nowadays deployed in many different experimental protocols, but their specific advantages and disadvantages are not well understood. These protocols have to be tested on a real platform to be qualified regarding application characteristics and network dynamics.

Congestion control.
Congestion control for multicast is an unsolved problem. There are two approaches to multicast congestion control : Rate based control (such as in TCP slow-start) and application based control (with techniques such as layered multicast or media-scaling). Congestion control is being studied in the Internet community as one of the compulsory mechanisms to enable the wide deployment of multicast.

Scalability: group management.
Having all the participants of a session in the same group is neither scalable, nor useful. The scalability problem is obvious. At the same time, each participant does not need to receive all information coming from all other participants. He will be mostly concerned by his neighbors, by his allied, by people with the same communication medium, etc. This will allow to subdivide the group of participants in sub-groups with different constraints and attributes.. Solutions are required to target very large group communication systems such as the one encountered in applications like distributed games, distributed interactive simulation, large scale document dissemination, etc. The dynamic of the group activity as well as the management of the group properties and semantic relationships between users will be addressed.

Multicast QoS capable architectures
The ability to support multipeer Quality of Service (QoS) will be studied for various technologies available today or in the near future such as IP, ATM, mobile networks, satellite networks or any kind of heterogeneous technology. The mechanisms mentioned above will be considered from the perspective of efficiency, network support or signaling.

The different technical issues described above are the foundation for the design of a multipeer communication infrastructure. Research work in this area requires a close cooperation of involved research groups in order to be efficient and converge to a coherent solution.

C.2. Infrastructure and dissemination

The target of this activity is to identify how to improve the existing infrastructure (mainly the Mbone) as well as provide the support for distributed multimedia experimentations and action dissemination :

Contributing to the improvement of the infrastructure

The infrastructure is mandatory for the action to settle a continuous efficient and active cooperation between the participants. It will also add to the international credibility of the action, in particular in the Internet community (IRTF and IETF). Improving the infrastructure will allow research groups to experiment with their work in a wide-area network, with the support of other European researchers.

The goal of this activity is to allow participants to share their experience in local or Mbone environments and provide recommendations and understanding to the deployment of an efficient infrastructure.

The action participants are already active in the research area of group communication. However, anytime they want to experiment with their algorithms and protocols, they face the problem of the lack of a robust experimental network infrastructure. They also face the absence of feedback from other research groups. This activity will have a direct influence on the importance and on the credibility of the action contributions. It will also allow the action to contribute, at the highest scientific level, in a domain where the USA have dominated for many years.

Dissemination of information:

Information dissemination is a key factor for efficient cooperation in research. Solutions such as multiparty conferencing, telephony, and CSCW (Cooperative Support for Collaborative Work), will be made available through the Costbone. It will allow all European countries to profit and/or to participate at their own technology level : as simple participants or as researchers. Moreover, design, test, and distribution of new multicast multimedia applications will be done through the entire action life. The results of the action will be made available to a large extend, to industry and research actors.

D) Organization and Timetable

The organization of the group will follow the standard form of Cost actions with the following initiatives : The duration of the action is 4 years.

The action will start with two areas that will be activated through the definition of working groups :

Area 1 : Research and experimentation
This area is targeting cooperation in important research issues in the domain of group communication, as mentioned in section 3. It is a technical area where we will discuss research activities carried out by the action participants, as well as research done in other organizations. It should become a major forum for research in Europe covering aspects ranging from multicast mechanisms to application design for group communication. Outputs will be delivered to standardization bodies. Cooperation with industry will also be promoted within this area.

Area 2 : Infrastructure and dissemination
This area is responsible for the activity related to the part " Infrastructure and dissemination " described above. It will consist in sharing experience with the Mbone utilization, and to identify possible improvements to the available infrastructure. This WG will be also in charge of scheduling seminars, conferences and experiments on the infrastructure.

A tightly coupled liaison will be established between the two areas and working groups will be defined to organize the related activities at the early stage of the project. Also, new working groups might appear and others get stopped if required by the evolution of the area and participants. The operational management will build on the one experimented for COST237.

* COST 264 Home Page
Last modif: 22/04/1998
Editor : S. Fdida -

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