HRD Programme for Exchange of ICT Researchers and Engineers Sponsored by APT QoS Multimedia Network

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HRD Programme for Exchange of ICTResearchers and
Engineers(Sponsored by APT) QoS Multimedia
Network Architecture(Proxy Caching Mechanisms)
Dr. Mahmood Ashraf KhanNational Post-Graduate
Institute of Telecommunication Informatics
(PTCL) Islamabad, Pakistan E-mail
mahmood_at_npgiti.edu.pk
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Collaborative Researchers

• Cyber-media Center, Murata laboratories, Osaka
  University, Japan
• Dr. Go-Hasegawa, Associate Prof.
• Mr. Yoshiaki Taniguchi
• Mr. Takuya Okamoto

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Background

• Growth of computing power
• Proliferation of the Internet
• Distributed multimedia applications

Increasing of video streaming services over the
Internet
High-quality and low-delay video streaming
service is required
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Parameters Effect the QOS of Multimedia network

• User Dynamism and Behaviour
• Bandwidth
• Digital Video Compression Techniques
• Traffic Analysis
• Proxy Caching

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User Dynamism and Behaviour

• User Interests
• Most favorite sites/videos
• Timings
• User hits
• User miss

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Traffic Analysis

• Number of requests
• statistical properties of the information
  transmitted for the requests
• peak rate,
• burstiness,
• average rate,
• Another important factor for traffic modeling is
  the video file characteristics.
• size,
• durations
• Bit-rate distributions.

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Bandwidth

• Most expensive part in multimedia networks
  Architecture
• At basic ISDN rates (around 128 Kbps) only 3-4
  of the titles can be streamed.
• At 700 Kbits/sec, 52 of all movies can be
  streamed.
• At 1.5 Mbits/sec 84 can be streamed.

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Proxy Caching

• Technique for low-delay data delivery
• Proxy mechanisms
• Widely used in WWW systems
• Reduce network load

Applying to the video transfer
Problems

• A current proxy system only handles files
  whereas a single video stream is very large

• A current proxy system only handles files
  whereas a single video stream is very large
• Client requests on the video quality
  considerably differ due to heterogeneity in
  the available bandwidth

• Segmentation of video data
• Video quality adjustment in the proxy

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Video streaming system using proxy cache
Server
Client 1
Proxy
MPEG-2 Video Stream
Cache Buffer
Client 2
Network
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Research Targets

• Proposal of proxy caching mechanisms
• Video quality adjustment
• Low-delay video streaming service while meeting
  users demand
• Data retrieval with consideration on clients
  request
• Pre-fetching data that clients are going to
  require in the future
• Reduce required cache buffer size
• Segmentation of video data for retrieval, caching
  and forwarding
• Replacement of cached data with consideration of
  size, quality and re-usability of data

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Video streaming system using proxy cache with
video quality adjustment
Server
Client 1
Proxy
MPEG-2 Video Stream
Cache Buffer
Client 2
Network
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Assumptions on proposed mechanisms

• MPEG-2 video
• Unit of data for retrieval, caching and
  forwarding
• GoP (Group of Pictures)
• A client periodically requests the proxy to send
  a GoP with users demand
• Available Bandwidth ----- Video quality

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Replacement Algorithm

• Choose a candidate GoP for replacement
• Try the quality adjustment to decrease the size
  of the candidate
• Eject the candidate from the cache

Video
Beginning
End
6
4
2
7
5
3
8
Priority
High
Low
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Data retrieval

• Cache hit
• The proxy adjusts cached GoP to the request and
  transmits it to the client
• Cache miss
• Server-Proxy bandwidth is sufficient
• Data retrieval with consideration on current and
  future demands
• Server-Proxy bandwidth is insufficient
• Data retrieval with consideration on trade-off
  between quality and delay

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Data retrieval- Sufficient bandwidth -

• Considering clients that are going to require
  the GoP in the future, the proxy retrieves the
  GoP of maximum quality among their demands

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Data retrieval- Insufficient bandwidth -

• Trade-off between quality and delay

Which does the user give priority to, quality or
timeliness?
Introducing a parameter b
b is defined as the ratio of the acceptable
quality to the demand
b
1
0
timeliness
quality
users preference
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Data retrieval- Insufficient bandwidth -

• Control based on b

Quality of cached GoP
³
b
Quality of the clients request
Yes
The proxy sends the cached GoP
No
Quality of the GoP which the proxy can retrieve
from the server
³
b
Quality of the clients request
Yes
The proxy retrieves the GoP from the server
No
Quality of the GoP which the proxy can provide

b
Quality of the clients request
The proxy retrieves the GoP of the acceptable
qualityfrom the server
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Simulation model
TCP sessions
TCP sessions
Client
Server
Router
Router
Router
Router
Proxy
UDP sessions
UDP sessions
150 Mbps
50 Mbps

• Video stream is two hours long
• 10 clients watch the same video stream from the
  beginning to the end without interactions
• The inter-arrival time between two successive
  client participations whose average is 1,800
  seconds

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Simulation result- Amount of cached data -
Traditional method (infinite cache, no quality
adjustment)
Proposed mechanism (infinite cache, no
prefetching, b 1)
Proposed mechanism (20 Gbits cache, prefetching,
b 0.6)
160
140
120
100
Amount of cached data Gbit
80
60
40
20
0
0
5000
10000
15000
20000
Time sec
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Simulation result- Playout delay -
Traditional method (infinite cache, no quality
adjustment)
Proposed mechanism (infinite cache, no
prefetching, b 1)
Proposed mechanism (20 Gbits cache, prefetching,
b 0.6)
25
20
15
Playout delay sec
10
5
0
0
1
2
3
4
5
6
7
8
9
Client
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Simulation result- Degree of satisfaction on
delivered video -
Traditional method (infinite cache, no quality
adjustment)
Proposed mechanism (infinite cache, no
prefetching, b 1)
Proposed mechanism (20 Gbits cache, prefetching,
b 0.6)
1
0.8
0.6
Degree of satisfaction on delivered video
0.4
0.2
0
0
1
2
3
4
5
6
7
8
9
Client
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Conclusion

• Conclusions
• Proposed proxy caching mechanisms with video
  quality adjustment
• Simulation results show that the system can
  accomplish a low-delay video streaming service
  while meeting users demand and available
  bandwidth
• Future works
• Reducing play-out delay
• Considering interactions such as rewinding,
  pausing and fast-forwarding

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Result/ Output of the Project

• The following was achieved during the
  Collaborative research
• One particular research area was deeply explored.
  
• A research group at Pakistan was formed to
  continue this research at Pakistan in
  collaboration with the research group at Osaka
  University, Japan.
• At the Masters level, the students/Faculty of our
  institute will conduct the research and share
  their results with the students/Faculty of Osaka
  University which will ultimately produce joint
  research publications.

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Recommendations

• The research Program was very valuable and this
  must be continued.
• The time duration of the collaborative research
  was very limited and this should be extended.
• More involvement of Japanese side is required as
  those researchers have much more knowledge and
  the developing countries can benefit from their
  rich research experience. This involvement can be
  through Distinguished Lectures series and joint
  research program.
• More focused faculty exchange Program should also
  be initiated.
• After investing capital on one team of
  researchers a follow-up programs must be prepared
  which will keep track of the researchers and
  investing a little more will have numerous
  long-lasting results.

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HRD/ICT Initiatives in Pakistan
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GoP Legal Policy Initiatives

• Telecommunication Ordinance 1996
• Pakistan Telecommunication Authority (PTA)
  1996
• IT Telecom Division MoST 1999
• IT Ordinance 2001
• Pakistan Media Regulatory Authority (PMRA) 2001
• Privatization Ordinance 2001
• Electronic Transaction Ordinance 2002
• Electronic Government Ordinance 2002
• Virtual University Ordinance 2002
• Ministry of IT Telecom 2002
• Telecom Deregulation Policy
  July 2003

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ICT/HRD initiatives in Pakistan

• Over the last 2 years billion of rupees under IT
  infrastructure development and IT Human Resource
  Development have been spent
• Establishing seven (7) public sector IT
  universities,
• Establishing a virtual university,
• 50 major private sector IT initiatives including
  CISCO, Oracle, Microsoft trainings and
  certifications
• Establishment of Educational Intranet.
• Providing free Internet service to All University
• Establishment of Telecom University (A project of
  PTCL)
• Catering for HRD requirement for the region
• Provide Post-Graduate education focused on
  Telecom
• Establishment of ITU regional CISCO Academy
• To Start functioning from Sept 2003
• First project to be started at Afghanistan

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Thank You