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

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

3. 3 Challenges UnreliabilityUnreliability – –Fading – –Noise Bandwidth fluctuationsBandwidth fluctuations – –Moving between different networks (LAN to WAN) – –Hand-off – –… Heterogeneity for multicastHeterogeneity for multicast

4. 4 Unicast vs. Multicast UnicastMulticast

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

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

7. 7 An Application: IP Multicast An Application: IP Multicast

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

9. 9 Outline Challenges for video over wireless IP networksChallenges for video over wireless IP networks An adaptive framework for video over wireless IP networksAn adaptive framework for video over wireless IP networks – –Scalable video representations – –Network-aware end systems – –Adaptive services SummarySummary

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

11. 11 Taxonomy of Network Monitoring Criteria Type of monitoring Method of monitoring ActivePassive Monitoring frequency On demand Continuous Replication of information CentralizedDistributed

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

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

14. 14 Outline Challenges for video over wireless IP networksChallenges for video over wireless IP networks An adaptive framework for video over wireless IP networksAn adaptive framework for video over wireless IP networks – –Scalable video representations – –Network-aware end systems – –Adaptive services SummarySummary

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

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

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

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

19. 19 Resource Reservation Different from the counterpart in wired networks:Different from the counterpart in wired networks: –The reserved bandwidth may not be rigidly guaranteed in wireless networks Two parts of resource reservationTwo 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. 20 Mobile multicast mechanism Objective:Objective: – –Provide seamless QoS during a handoff Multicast mechanism:Multicast mechanism: – –Multicast the base layer to the neighboring base stations

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

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

23. 23 Utility Functions

24. 24 Substream Scheduling

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

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

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