Scalable Video Transport over Wireless IP Networks

Dapeng WuElectrical & Computer Engineering

University of Florida

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Bandwidth FluctuationsBandwidth Fluctuations

Domain A

Domain B

Domain C

InternetSource

Receiver

AccessAccessSWSW

AccessAccessSWSW

GatewayGateway

64 kb/s

1 Mb/s

Cellular NetworksWireless LAN

Mobile PCMobile PC

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ChallengesChallenges• UnreliabilityUnreliability

– Fading– Noise

• Bandwidth fluctuationsBandwidth fluctuations– Moving between different networks (LAN to

WAN)– Hand-off– …

• Heterogeneity for multicastHeterogeneity for multicast

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Unicast vs. MulticastUnicast vs. Multicast

Unicast Multicast

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Three Independent TechniquesThree 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 QoS support from networks: adaptive servicesadaptive services

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Scalable Video RepresentationsScalable Video Representations

Layered video encoding/decoding. D denotes the decoder.Layered video encoding/decoding. D denotes the decoder.

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An Application: IP MulticastAn Application: IP Multicast

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Our ApproachOur Approach

• Unify the three techniques: Unify the three techniques: an adaptive frameworkan adaptive framework

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OutlineOutline• Challenges for video over wireless IP Challenges for video over wireless IP

networksnetworks• An adaptive framework for video over An adaptive framework for video over

wireless IP networkswireless IP networks– Scalable video representations– Network-aware end systems– Adaptive services

• SummarySummary

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Network-aware End SystemsNetwork-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

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Taxonomy of Network Monitoring Taxonomy of Network Monitoring

CriteriaCriteria Type of monitoringType of monitoringMethod of monitoringMethod of monitoring ActiveActive PassivePassiveMonitoring frequencyMonitoring frequency On demandOn demand ContinuousContinuousReplication of informationReplication of information CentralizedCentralized DistributedDistributed

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Adaptation/ScalingAdaptation/Scaling

An architecture for transporting scalable video from a mobile terminal An architecture for transporting scalable video from a mobile terminal to a wired terminal.to a wired terminal.

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ScalingScaling

• 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)

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OutlineOutline• Challenges for video over wireless IP Challenges for video over wireless IP

networksnetworks• An adaptive framework for video over An adaptive framework for video over

wireless IP networkswireless IP networks– Scalable video representations– Network-aware end systems– Adaptive services

• SummarySummary

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Adaptive ServicesAdaptive 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

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Adaptive Services (cont’d)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

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Service ContractService Contract• A service contract consists of multiple A service contract consists of multiple

subcontractssubcontracts– Bandwidth reservation for the base layer – No QoS guarantee for enhancement layers

• EnforcementEnforcement– Shaping– Priority

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Call Admission Control (CAC)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

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Resource ReservationResource Reservation• Different from the counterpart in wired Different from the counterpart in wired

networks: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

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Mobile multicast mechanismMobile multicast mechanism

• Objective:Objective:– Provide seamless QoS during a handoff

• Multicast mechanism: Multicast mechanism: – Multicast the base layer to the neighboring base

stations

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Substream ScalingSubstream Scaling

• Objective:Objective:– Adapt video streams during bandwidth

fluctuations and/or under poor channel conditions• Scaling decision based on utility fairness or Scaling decision based on utility fairness or

max-min fairnessmax-min fairness– Utility fairness is based on utility functions– Max-min fairness is based on revenue

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Substream Scaling (cont’d)Substream Scaling (cont’d)

An architecture for transporting scalable video from a wired terminalAn architecture for transporting scalable video from a wired terminalto a mobile terminal.to a mobile terminal.

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Utility FunctionsUtility Functions

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Substream SchedulingSubstream Scheduling

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Link-layer Error ControlLink-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

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Delay-constrained Hybrid ARQDelay-constrained Hybrid ARQ

RCPC: Rate compatible punctured convolution

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SummarySummary• Objective: end-to-end solution to providing QoS for Objective: end-to-end solution to providing QoS for

video transport over wireless IP networksvideo transport over wireless IP networks• Our approach: Our approach: an adaptive frameworkan 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