QoS specification and mapping for distributed multimedia systems: A survey of issues

The drastic improvement of network performance in terms of throughput and error rate coupled with the continuous increase in power of end-systems have led to the emergence of a variety of distributed Multimedia (MM) applications. The performance levels required by the distributed MM systems are expressed as Quality of Service (QoS). Network QoS support alone cannot guarantee the real-time performance required for distributed MM applications. Successful operation of distributed MM systems depends on the guaranteed support of all intervening layers including the end-systems. The guaranteed performance of these layers in turn is a€ected by the eciency of the support provided by: QoS speci®cation, QoS mapping or translation, QoS negotiation and re-negotiation, Resource monitoring and adaptation, and QoS architectures. Most people usually have a good understanding of a certain layer but not the others. However, to be able to deliver MM QoS, developers need to have a better understanding of several layers. This paper focuses on QoS speci®cation and mapping and aims to provide a survey of issues for those working on MM QoS so that they have a better view on these two areas which are important to MM QoS. Ó 1999 Elsevier Science Inc. All rights reserved.