MPEG-21-based Cross-Layer Optimization Techniques for enabling Quality of Experience Christian Timmerer Klagenfurt University (UNIKLU) Faculty of Technical Sciences (TEWI) Department of Information Technology (ITEC) Multimedia Communication (MMC) http://research.timmerer.com http://blog.timmerer.com mailto:[email protected]Acknowledgments: DANAE, ENTHRONE, P2P-Next, ALICANTE projects funded by EC, SCALIPTV/SCALNET funded by FFG, ASSSV funded by FWF and, in particular Michael Eberhard, Ingo Kofler, Robert Kuschnig, Michael Ransburg, Michael Sablatschan, Hermann Hellwagner
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MPEG-21-based Cross-Layer Optimization Techniques for enabling Quality of Experience
Presentation at MMT workshop in Kyoto during the 91st MPEG meeting...
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MPEG-21-based Cross-Layer Optimization Techniques for enabling Quality of Experience
Christian Timmerer
Klagenfurt University (UNIKLU) Faculty of Technical Sciences (TEWI)
Department of Information Technology (ITEC) Multimedia Communication (MMC)
Acknowledgments: DANAE, ENTHRONE, P2P-Next, ALICANTE projects funded by EC, SCALIPTV/SCALNET funded by FFG, ASSSV funded by FWF and, in particular Michael Eberhard, Ingo Kofler, Robert Kuschnig, Michael Ransburg, Michael Sablatschan, Hermann Hellwagner
Outline
• Background / Introduction
– Cross-layer designs & optimizations– MPEG-21 Digital Item Adaptation
• How to exploit MPEG-21 for XL optimizations?
– Cross-Layer Model (XLM)– Instantiation of the XLM by utilizing MPEG-21
across the network layers => violating the protocol hierarchy and isolation model
– Approaches: bottom-up or a top-down or jointly optimizing parameters at the different layers
– Common property: compromising interoperability in favor of performance
• Increasing the interoperability of cross-layer designs by adopting an open standard – MPEG-21 Digital Item Adaptation – for describing the functional dependencies across network layers
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Digital Item AdaptationDIA := syntax and semantics of tools that assist in the adaptation of Digital Items
Goals:• Satisfy transmission, storage and
consumption constraints as well asQuality of Service (QoS) management
• Enable transparent access to (distributed)advanced multimedia content by shieldingusers from network and terminal installationissues
• Codec Format-independent mechanisms that provide support for Digital Item Adaptation in terms of:– Resource adaptation– Description adaptation– Quality of Service management
• The adaptation engines themselves are non-normative tools2010/01/20 Christian Timmerer, Klagenfurt University, Austria 4
fundamental inputto any adaptation engine
2010/01/20 Christian Timmerer, Klagenfurt University, Austria
Context-related metadata describes the usage environment in terms of terminal capabilities; network characteristics; user characteristics; natural environment characteristics;
AdaptationQoS and Universal Constraints Description
• Content-related metadata – AdaptationQoS– describes the relationship between constraints; feasible adaptation operations satisfying these constraints; associated utilities (qualities);
e.g., available bandwidth is 384kbps, terminal display is CIF; reduce bit-rate; quality at QCIF/30fps/QP=10 versus CIF/10fps/QP=15e.g., bit-rate = 256kbps, frame-rate=30fps, resolution=CIF, etc.
• Universal Constraints Description (UCD): mathematical approach based on an optimization problem– find values for the variables representing adaptation parameters that do
not violate the limitation constraints (feasibility) and maximize the optimization constraint(optimality, objective function)
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How to exploit MPEG-21 for XL optimizations?
Three-step approach1. Cross-Layer Model (XLM): describing the relationship between QoS
metrics at different levels – No specific notation (e.g., graphical)– For example:
2. Instantiation of the XLM by utilizing MPEG-21 metadata– AdaptationQoS (AQoS): describe the relationship between constraints,
feasible adaptation operations satisfying these constraints, and associated utilities (qualities)
– Usage Environment Description (UED): context information (network conditions, terminal capabilities, user preferences, etc.)
– Universal Constraints Description (UCD): limitation and optimization constraints
3. Cross-Layer Adaptation Decision-Taking Engine (XL-ADTE)– Software module solving an optimization problem adopting any algorithm
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Example: Adaptive XL-based Streaming
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TID, DID, QID
max. payload size, forward error correction
supported display resolution, frame-rate
packet loss, jitter
signal strength, physical rate
temporal id (TID)dependency id (DID)quality id (QID)packet size
vertical and horizontal resolutionbit rateframe rate
Basic Cross-Layer Model
Advanced Cross-Layer Model
• Desirable characteristics– TCP friendliness: long-term throughput similar to TCP– Responsiveness: time to act upon a certain event– Smoothness: variation experienced for a particular flow
• TCP-friendly Rate Control Protocol (TFRC)
– Throughput T in bytes/sec is modeled as a function of• Segment size sin bytes• RTT estimate r in seconds• Loss event rate pas a fraction between 0.0 and 1.0• TCP retransmission timeout value tRTOin seconds (simple tRTO= 4r)
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Instantiation of XLM using MPEG-21
• AdaptationQoS (AQoS)– Parameters (TID, …) as IOPins– Basic XL model as Look-Up Table (LUT)– Advanced XL model as Stack Function (SF)
• Usage Environment Description (UED)– Display resolution as display capabilities– Max bit-rate of codec as codec capabilities– RTT as packetTwoWay– Loss event rate by using the packetLossRate