Experiences with Multimedia Streaming over 2.5G and 3G Networks

1
Experiences with Multimedia Streaming over 2.5G
and 3G Networks

• J. Chesterfield, R. Chakravorty, J. Crowcroft, P.
  Rodriguez, S. Banerjee
• Presented by Denny Iskandar

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1. Introduction

• What?
• Evaluates performance of multimedia streaming
  over wireless network.
• Why?
• 2.5G and 3G technologies are being deployed
  everywhere (Europe, America, and Asia)
• Popularity of multimedia applications such as
  videoconferencing, Voice over IP, and audio/video
  broadcasting

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1. Introduction

• Scope of experiment
• Measurements from real networks
• The effect of heterogeneity of network is
  captured by comparison across different network
  technologies (GSM), GPRS, and UMTS.
• Describes the importance of cooperation between
  network and application using an application
  called vorbistreamer.

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Roadmap

1. Introduction
2. Network measurements
3. Application measurements
4. Conclusions

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2. Network Measurements

• Multimedia traffic characterization
• Assume layered organization of media
• Bandwidth used ranges between a minimum and a
  maximum target rate.

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2. Network Measurements

• 2.1 Propagation delay and jitter

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2. Network Measurements

• 2.1 Propagation delay and jitter

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2. Network Measurements

• 2.1 Propagation delay and jitter
• Compare with ITU recommendation for voice
  communications RTT 500 ms

GSM GPRS UMTS
Mean 1460 ms 220 ms 30 ms
Variance Not mentioned 80-500 ms 20-300 ms
Note For GPRS, disabling ARQ reduces jitter at
the cost of higher packet loss rate (around 3).
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2. Network Measurements

• 2.2 Capacity variation

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2. Network Measurements

• 2.2 Capacity variation

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2. Network Measurements

• 2.3 Summary
• Propagation delay and delay jitter are reduced as
  link capacity increases.
• GPRS should disable ARQ for multimedia
  application.
• Sub-packet error detection 1 improves
  performance.

1 J. Chesterfield, R. Chakravorty, S. Banerjee,
P. Rodriguez and I. Pratt. Transport Level
Optimisations for Interactive Media Streaming
Over Wide-Area Wireless Networks. In WiOpt 04,
2004.
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3. Application Measurements

• Use Vorbis codec
• A layered codec, encodes data into a base layer
  and enhancement layers

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3. Application Measurements

• Design of vorbistreamer
• Implements IP-based data striping this is used
  to aggregate channel bandwidth.
• Uses RTP as transport protocol.
• Supports interactivity constraints from fully
  interactive communication to one-way streaming.
• Uses Vorbis codec.

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3. Application Measurements

• Encoding techniques
• For multimedia application, reliability is
  disabled
• Needs to add redundancy to multimedia data to
  facilitate receiver-based repairs
• Also involves interleaving of encoding blocks to
  reduce the effect of error burst

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3. Application Measurements

• 3.1 Intra-packet redundancy (UEP)

Vorbis frame
Header
Base layer
EL1
EL2
ELn
...
FEC1
FEC2
frame1
n-2 frames
RLC packets
FEC blocks
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3. Application Measurements

• Things to note
• This bucketing is done at application layer,
  the actual RLC packetization is done at link
  layer.
• Multiple layers in one packet to minimize header
  overhead.

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3. Application Measurements

• 3.2 Inter-packet redundancy
• Cross-packet coding
• Sends parity data in separate packets than the
  original data.

original data
parity data
d

• The greater d is
• The more effective recovery
• The greater recovery delay

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3. Application Measurements

• 3.2 Inter-packet redundancy
• Cross-channel coding
• From tests, it is more likely that error occurs
  to A and B than to B and C

A
B
channel 1
C
channel 2
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3. Application Measurements

• 3.3 Interleaving
• Intra-packet change the order of frames in the
  same packet
• Inter-packet change the order of packets in the
  same channel
• Inter-channel

5
3
1
7
channel 1
6
4
2
8
channel 2
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3. Application Measurements

• 3.4 Comparison

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4. Conclusions

• The need for cooperation between network and
  application.
• Encoding and organization of multimedia data is
  important.
• Benefits from aggregating independent channels.
• Benefits from sub-packet error detection.

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5. Related works

• 1 J. Chesterfield, R. Chakravorty, S. Banerjee,
  P. Rodriguez and I. Pratt. Transport Level
  Optimisations for Interactive Media Streaming
  Over Wide-Area Wireless Networks. In WiOpt04
  Modelling and Optimization in Mobile, Ad Hoc and
  Wireless Networks, 2004.
• 2 R. Chakravorty, J. Chesterfield, P. Rodriguez
  and S. Banerjee. Measurement Approaches to
  Evaluate Performance Optimizations for Wide-Area
  Wireless Networks. In Passive and Active Network
  Measurement (PAM 2004) 5th International
  Workshop, 2004.