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Scalable Video Transport over Wireless IP Networks

Scalable Video Transport over Wireless IP Networks. Dapeng Wu Electrical & Computer Engineering University of Florida. Bandwidth Fluctuations. Access SW. Cellular Networks. Access SW. Domain B. Domain A. Domain C. Internet. Source. Gateway. Wireless LAN. 1 Mb/s. Receiver .

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Scalable Video Transport over Wireless IP Networks

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  1. Scalable Video Transport over Wireless IP Networks Dapeng Wu Electrical & Computer Engineering University of Florida

  2. Bandwidth Fluctuations Access SW Cellular Networks Access SW Domain B Domain A Domain C Internet Source Gateway Wireless LAN 1 Mb/s Receiver 64 kb/s Mobile PC Mobile PC

  3. Challenges • Unreliability • Fading • Noise • Bandwidth fluctuations • Moving between different networks (LAN to WAN) • Hand-off • … • Heterogeneity for multicast

  4. Unicast vs. Multicast Unicast Multicast

  5. Three Independent Techniques • Scalable video coding • Network-aware adaptation of end systems • Network awareness • Adaptation • Adaptive QoS support from networks: adaptive services

  6. Scalable Video Representations Layered video encoding/decoding. D denotes the decoder.

  7. An Application: IP Multicast

  8. Our Approach • Unify the three techniques: • an adaptive framework

  9. Outline • Challenges for video over wireless IP networks • An adaptive framework for video over wireless IP networks • Scalable video representations • Network-aware end systems • Adaptive services • Summary

  10. Network-aware End Systems • Why using network-aware end systems? • All layers may get corrupted with equal probability without awareness of channel status • How? • Discard enhancement layers at the sender based on network status • Network-aware adaptation: • Network monitoring: collect information • Adaptation: adapt video representations based on network status

  11. Taxonomy of Network Monitoring

  12. Adaptation/Scaling An architecture for transporting scalable video from a mobile terminal to a wired terminal.

  13. Scaling • The operations of a scaler • Drop the enhancement layers • Do not scale the video • Scaling based on network status • Available bandwidth • Channel quality (BER)

  14. Outline • Challenges for video over wireless IP networks • An adaptive framework for video over wireless IP networks • Scalable video representations • Network-aware end systems • Adaptive services • Summary

  15. Adaptive Services • Objective: • achieve smooth change of perceptual quality in presence of bandwidth fluctuations. • Functions: • Reserve a minimum bandwidth for the base layer • Adapt enhancement layers based on available bandwidth and the fairness policy

  16. Adaptive Services (cont’d) • Provisioning • End-to-end deployment (our focus) • Local deployment • Components: • Service contract • Call admission control and resource reservation • Substream scaling • Substream scheduling • Link-layer error control

  17. Service Contract • A service contract consists of multiple subcontracts • Bandwidth reservation for the base layer • No QoS guarantee for enhancement layers • Enforcement • Shaping • Priority

  18. Call Admission Control (CAC) • Objective: • Provide a QoS guarantee while efficiently utilizing network resources • The operation of CAC: check • whether QoS for existing connections is violated • whether the incoming connection’s QoS can be met

  19. Resource Reservation • Different from the counterpart in wired networks: • The reserved bandwidth may not be rigidly guaranteed in wireless networks • Two parts of resource reservation • Reserve resources along the current path • Reserve resource on the paths from the current base station to neighboring base stations

  20. Mobile multicast mechanism • Objective: • Provide seamless QoS during a handoff • Multicast mechanism: • Multicast the base layer to the neighboring base stations

  21. Substream Scaling • Objective: • Adapt video streams during bandwidth fluctuations and/or under poor channel conditions • Scaling decision based on utility fairness or max-min fairness • Utility fairness is based on utility functions • Max-min fairness is based on revenue

  22. Substream Scaling (cont’d) An architecture for transporting scalable video from a wired terminal to a mobile terminal.

  23. Utility Functions

  24. Substream Scheduling

  25. Link-layer Error Control • Forward error correction (FEC) • Automatic repeat request (ARQ) • Truncated type-II hybrid ARQ • Delay constrained hybrid ARQ • A receiver sends request based on delay bound of the packet

  26. Delay-constrained Hybrid ARQ RCPC: Rate compatible punctured convolution

  27. Summary • Objective: end-to-end solution to providing QoS for video transport over wireless IP networks • Our approach: an adaptive framework • Scalable video representations • Network-aware end systems • Adaptive services • Advantages of the adaptive framework • Perceptual quality is changed gracefully • Resources are shared in a fair manner

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