As the ATM technique matures several solutions have been proposed for the integration of video codecs in the broadband ISDN. At present, two approaches can be distinguishedThe first aims at the integration of video codecs, that were developedfor synchronous networks, in the ATM network For these codecs, adoptors are developed that provide the necessary circuit emulation over the ATM network, with the required quality. In the paper special attention is paid to synchronization, dejittering and cell loss protection issues.The second scenario is bared on a new generation of video codecs that a n being developed especially for the ATM network These codecs take full advantage of the flexibility offered by the ATM network, and allow cell loss concealment techniques to be used. In the paper Variable Bit Rate video coding and the associated bandwidrh allocation and policing algorithms are discussed. Special features such as user selectable picture quality are shown Cell loss detection and concealment techniques are discussed.

This paper presents a Model of Quality of Service (QoS) for Next Generation Networks (NGN), which consists of a tower of five layers defined as Model Layer QoS, Admission Control, QoS routing, QoS signaling, MAC and QoS. The model also presents a method based on the concept of segregation of functions defining two functional networks with QoS tasks. Then, Access Control policies, protocols and algorithms, signaling and routing, as well as aspects related to media access are established. To verify the performance of the model, a Design of Experiments on a NGN Pilot was designed over simulation tool OPNET Modeler. The statistical analysis consisted of an analysis of variance on the output variables Delay, Jitter and Throughput, whose outcome determined the significant factors that impacted the model metrics.

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