MPEG-21-based Cross-Layer Optimization Techniques for enabling Quality of Experience

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:christian.timmerer@itec.uni-klu.ac.at
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 metadata
Cross-Layer Adaptation Decision-Taking Engine (XL-ADTE)
Conclusions
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Christian Timmerer, Klagenfurt University, Austria

Background / Introduction
Cross-layer designs
Aim: increase QoS/QoEby performing coordinated actions 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 Adaptation
DIA := syntax and semantics of tools that assist in the adaptation of Digital Items
Goals:
Satisfy transmission, storage andconsumption 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 tools
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Usage Environment Description (UED)
Terminal Capabilities
Codec Capabilities
Device Properties
Input-Output Characteristics
User Characteristics
User Info
Usage Preference & History
Presentation Preferences
Accessibility
Location
fundamental inputto any adaptation engine
Natural Environment Characteristics
Location & Time
Audio-Visual
Network Characteristics
Capabilities
Conditions
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Context-related metadata describes the usage environment in terms of terminal capabilities; network characteristics; user characteristics; natural environment characteristics;
e.g., codec capabilities = mp2, ML@MP; available bandwidth=1500kbps; visually impaired; high-level ambient noise;

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 approach
Cross-Layer Model (XLM): describing the relationship between QoS metrics at different levels
No specific notation (e.g., graphical)
For example:
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
Software module solving an optimization problem adopting any algorithm
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Example: Adaptive XL-based Streaming
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supported display resolution, frame-rate
TID, DID, QID
packet loss, jitter
max. payload size, forward error correction
signal strength, physical rate
Basic Cross-Layer Model
temporal id (TID)
dependency id (DID)
quality id (QID)
packet size
vertical and horizontal resolution
bit rate
frame rate

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)
Adapts sending rate accordingly
If Tcurr > Tnewthen reduce rate else increase rate
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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
Universal Constraints Description (UCD)
Limit constraints
resulting bit-rate < TFRC transmit rate
resulting bit-rate < max bit-rate of codec
video resolution < display size
Optimization constraint: max bit-rate
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Cross-Layer Adaptation Decision-Taking Engine (XL-ADTE)Example: Adaptation of Scalable Video
MPEG/ITU-T Scalable Video Coding (SVC)
3 dimensions of scalability: spatial, temporal, signal-to-noise ratio (SNR)
Spatial dimension [pixels]: 640x360, 1024x576, 1920x1080
Temporal dimension [fps]: 15, 30
Step 1: Determine Variables
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Table 1. (a) Adaptation Parameter Variables; (b) Content Property Variables.

Example: Adaptation of Scalable Video (cont’d)
Step 2: Identify Functional Dependencies
Step 3: Restrict Solution Space (Limit Constraints)
Step 4: Define Objective Function
maximize FrameRate
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Example: Adaptation of Scalable Video (cont’d)
Possible adaptation parameters
Feasible adaptation parameters
Optimal adaptation parameters
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Conclusions
Three steps to cross-layer interoperability
Cross-Layer Model (XLM): describing the relationship between QoS metrics at different levels
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Thank you for your attention
... questions, comments, etc. are welcome …
Ass.-Prof. Dipl.-Ing. Dr. Christian Timmerer
Klagenfurt University, Department of Information Technology (ITEC)
Universitätsstrasse 65-67, A-9020 Klagenfurt, AUSTRIA
christian.timmerer@itec.uni-klu.ac.at
http://research.timmerer.com/
Tel: +43/463/2700 3621 Fax: +43/463/2700 3699
© Copyright: Christian Timmerer
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2010/01/20

MPEG-21-based Cross-Layer Optimization Techniques for enabling Quality of Experience

by Alpen-Adria-Universität Klagenfurt on Jan 21, 2010

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