PostScript (860 KB)Meeting End-to-End QoS Challenges for Adaptive Digital Video Flows
Proceedings, 6th IFIP International Conference on High Performance Networking, Palma de Mallorca, Spain, September 1995
Abstract
We introduce the concept of Dynamic QoS Management (DQM) for management of hierarchically coded flows operating in heterogeneous multimedia networking environments. The motivation that underpins our scheme is to bridge the heterogenity gap that exists between applications, end-systems and networks. QoS adaptors, QoS filters, QoS Groups and flow monitors are key adaptive objects used in resolving QoS capability mismatch. QoS filters manipulate hierarchically coded flows as they progress through the communications system, QoS adapators scale flows at the end-systems based on the flow's measured performance and user supplied adaptation policy, and QoS Groups provide a baseline QoS for multicast communications. The focus of the work is driven by a) the special features of scalable MPEG-2 video, and b) the needs of both scalable and single-layer video for transmission over multimedia networks such as ATM. Two key techniques that can facilitate this architecture are discussed: Dynamic Rate Shaping of coded video and the Weighted Fair Share service. Dynamic rate shaping is a novel source-based QoS filter for manipulating the rate of MPEG-coded flows, matching it to the available network resources while minimizing the distortion observed at the receiver. Weighted Fair Share is a new adaptive service that can support dynamic QoS management by offering a mix of "hard" and "firm" QoS guarantees, in addition to resource fairness.