Transmitting Scalable Video over a DiffServ network

1
Transmitting Scalable Video over a DiffServ
network

• EE368C
• Project Presentation
• Sangeun Han, Athina Markopoulou
• 3/6/01

2
Project Proposal

• Problem
• Video transmission over the heterogeneous
  Internet
• Facts
• Scalability different parts of a video stream
  contribute unequally to the quality.
• DiffServ Networks can provide service
  differentiation, based on the marking of packets.
• Proposal
• Limit the effect of loss when it happens.
  Prioritize information according to importance
  and drop packets accordingly.

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Specifics

• What type of scalability? H.263, SNR
• Which DiffServ class? AF (priority dropping)

EI
EP
EP
EP
EL
I
P
P
P
BL
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Simulation scenario
Main stream Foreman (10fps) 136Kbps, BLEL, 2min
10-20 Interfering Streams BLEL136Kbps random
parts of 6 different streams
Single AF queue, 2 levels, 100KB
1.5Mbps
H.263 Encoder Layering
RTP Packet. for H.263 ()
Decoding Error Conceal. ()
Depackt.
Marker
Loss info
() Mode A at frame level, Total header
IP(20)UDP(8)RTP(12)H.263(4)44B
Original Stream
() Freezing previous frame
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Objective of the Project

• Show the benefit from using Priority Dropping for
  Scalable Video
• MUX gain
• Graceful Quality Degradation
• Handle short term congestion
• Configuration
• AF queue
• buffer management, thresholds, other parameters
• Layering parameters
• base layer, temporal dependence
• Recommendation
• To Feedback or to Drop?

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MUX gain
LayeredPD
Nonlayered
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Graceful degradation with loss
NL, no loss
Layeredloss
Non Layered loss
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Short Term Congestion

• The source may react to congestion by adapting
  its transmission rate...

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Reaction time vs.congestion duration

• Simple example
• 10 streams 5 more in 55sec,65sec
• 10 streams react by dropping their EL in 55D,
  65D

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Heavier congestion

• Heavy non adaptive interfering traffic
• 10 streams 10 more in 55sec,65sec
• 10 streams react by dropping their EL in 55D,
  65D

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Priority dropping vs Feedback

• Feedback
• is limited by delay
• saves network resources
• requires coordination

• Priority Dropping
• is like reaction in D0, by appropriate rate
  decrease
• may handle non adaptive sources

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Configuration of AF queue

• Choices
• Thresholds for the different priorities
• Buffer management RED or DropTail?
• Observations
• Not sensitive to choice of thresholds
• RED inappropriate do not use Avg Qsize, set
  LminLmax
• Differentiation (I) different thresholds (II)
  Occupancy

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RED worse than DropTail
For all loads.
for all thresholds
and
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Threshold for EL(HP)

• By assigning the buffer thresholds
• we control the Queue Occupancy for BL, EL

Threshold_HDP 56
Threshold_HDP 16
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Threshold for EL(LP)

• this way we distribute the loss among BL and EL

• .and thus the quality

• Insensitive to
• RED, DropTail
• BL choice
• more sensitive to load

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Effect of BL (I) on quality degradation
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Effect of BL (II) on thresholds
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Transmission of Scalable Video

• Use feedback adaptation at the source to match
  the transmission rate with the bottleneck
  bandwidth, to save network resources along the
  path
• Use Priority Dropping to handle short term
  congestion

Quality
Feedback
BL2
BL1
PD
Rate
loss
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Future work

• Improvements needed
• realistic feedback adaptation
• gt2 layers
• finish FGS
• New experiments needed
• Delay aspect
• Loss at the playback buffer
• Entire streams having different delay
  requirements
• Multiple hops
• Single wireless hop (802.11 QoS)
• Video Data
• Larger Bandwidths
• Other types of scalability FGS, Temporal,
  Spatial, DP