| Abstract |
Broadband Integrated Services Digital Networks (B-ISDN) aim to support a variety of services, including the transfer of video, audio and data. Asynchronous Transfer Mode (ATM) has been chosen as the switching and multiplexing technique for the implementation of B-ISDN. ATM has defined several classes of service with differing guarantees concerning the Quality of Service (QoS). ABR (Available Bit Rate) is the class in which connections share the bandwidth that remains available from the guaranteed classes of services. The applications transferred over ABR connections will adapt their transmit rate according to feedback from the network. Several schemes have been proposed for charging for application traffic that is transferred over ABR connections. The effects that the economic sharing of bandwidth has upon the users and upon the system need to be examined. At time of writing and implementing there is as yet no hardware implementation of the explicit-rate control mechanism defined by the ABR class. This made it necessary to design and build a realistic architecture emulating the mechanism discussed above in order to demonstrate the effects of charging schemes. In this Master's thesis we present the design and the implementation details of an advanced realistic architecture for charging MPEG System streams (video and audio) transferred over ABR connections. The implemented architecture is being used for charging experiments which show the effects that the negotiation of the charging parameters and the change of the available bandwidth has upon the application, the user's behavior and the system. The use of MPEG System streams gives a clear audio-visual prove of the consequences of economic sharing of bandwidth. This is done by adapting (traffic shaping) the stream's rate and carefully discarding information when necessary, which has an impact on the received quality of both video and audio. The architecture also takes advantage of the use of Intelligent Agents (IA) which rely on the user side. It has been proved that, IA help the user to renegotiate the charging parameter fast, by imitating the user's behavior, about the money he wants to pay and the QoS he wants to receive. The whole architecture and implementation is fully compliant with the proposals made to the International Standards Organization (ISO), for both the network part (ATM Forum, TINA-C) and the charged application part (MPEG). For the implementation we have used all the modern ideas from the Distributed Processing Environments area (CORBA), as well as a real ATM Network to support the transfer of the video/audio via AAL5, and the other communication information (TCP/IP over ATM). We have created a general and flexible system, enabling easy addition of new operations regarding the charging schemes or the application that is being charged.
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Σχεδίαση και Υλοποίηση μιας Ρεαλιστικής Αρχιτεκτονικής για Χρέωση MPEG video&ήχου Μεταφερομένων Μέσω Συνδέσεων ABR
