Presentation at MMT workshop in Kyoto during the 91st MPEG meeting...

1. 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

2. 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 2010/01/20 2 Christian Timmerer, Klagenfurt University, Austria

3. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 3

4. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 4

6. Device Properties

8. Usage Preference & History

9. Presentation Preferences

10. Accessibility

13. Conditions5 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;

14. 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) 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 6

15. 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: 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 Cross-Layer Adaptation Decision-Taking Engine (XL-ADTE) Software module solving an optimization problem adopting any algorithm 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 7

16. Example: Adaptive XL-based Streaming 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 8 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

17. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 9

18. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 10

19. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 11 Table 1. (a) Adaptation Parameter Variables; (b) Content Property Variables.

20. 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 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 12

21. Example: Adaptation of Scalable Video (cont’d) Possible adaptation parameters Feasible adaptation parameters Optimal adaptation parameters 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 13

22. Conclusions Three steps to cross-layer interoperability Cross-Layer Model (XLM): describing the relationship between QoS metrics at different levels Instantiation of the XLM by utilizing MPEG-21 metadata Cross-Layer Adaptation Decision-Taking Engine (XL-ADTE) 2010/01/20 Christian Timmerer, Klagenfurt University, Austria 14

23. 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 15 2010/01/20 Christian Timmerer, Klagenfurt University, Austria