A Fixed-Delay Broadcasting Protocol for Video-on-Demand

1
A Fixed-Delay Broadcasting Protocol for
Video-on-Demand

• Jehan-Francois Paris
• Department of Computer Science University of
  Houston

A Channel-Based Heuristic Distribution Protocol
For Video-on-Demand
Qiong Zhang Department of Computer Science
University of Houston
2
Outline

• Previous schemes
• Fixed-delay pagoda broadcasting
• Channel based heuristic distribution
• Conclusion

3
Fast broadcasting and Pagoda broadcasting
Fast Broadcast
Pagoda Broadcast
d
d
S1
S1
S1
S1
C1
S1
S1
S1
S1
C1
S1
S1
S2
S3
S2
S3
C2
S2
S4
S2
S5
C2
S2
S4
S4
S5
S6
S7
C3
S3
S6
S8
S3
C3
S7
S9
1/4 1/7
1/6 1/7
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Fixed-delay pagoda broadcasting(FDPB)

• It implements a fixed-delay policy that results
  in lower bandwidth requirements than other pagoda
  protocols.
• It uses a much simpler segment-to-channel mapping.

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Waiting time

• All customers need to wait for a fixed time
  interval w md, where m is some integer m 1
• Previous scheme
• Segment Si need to be repeated at least once
  every i slots
• This paper
• Segment Si need to be repeated at least once
  every mi-1 slots

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Subchannel

• The FDPB protocol partitions each channel Cj into
  sj subchannels in such a way that slot j of
  channel Cj belongs to its subchannel j (mod sj).

b/3
b/3
b/3
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Optimal number of subchannels

• Let Si be the first segment assigned to channel
  Cj , then channel Cj is partitioned into
  subchannels.
• For example (m 9, i 1)

Waiting time md
First segment S1
8
The first channel for m 9
1
C1
1/3
Subchannel 0
Subchannel 1
Subchannel 2
S1 1/9 (needs to be repeated at least once
every 9 slots)
Repeat 4 segments (1/3)/4 1/12 lt 1/9
Repeat 3 segments (1/3)/3 1/9 1/9
S1, S2, S3
9
The first channel for m 9
1
C2
1/3
Subchannel 0
Subchannel 1
Subchannel 2
S4 1/(94-1) 1/13 (needs to be repeated at
least once every 13 slots)
Repeat 5 segments (1/3)/5 1/15 lt 1/13
Repeat 4 segments (1/3)/4 1/12 1/13
S4, S5, S6, S7
10
The first channel for m 9
0
1
2
S1
S4
S8
S2
S5
S9
S3
S6
S10
S7
S11
S12
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The second channel for m 9
1
C1
(m 9 , i 13)
1/5
Subchannel 0
Subchannel 1
Subchannel 2
Subchannel 3
Subchannel 4
S13 1/(913-1) 1/21 (needs to be repeated at
least once every 21 slots)
Repeat 5 segments (1/5)/5 1/25 lt 1/21
Repeat 4 segments (1/5)/4 1/20 1/21
S13, S14, S15, S16
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The second channel for m 9
3
4
0
1
2
S13
S17
S22
S28
S35
S14
S18
S23
S29
S36
S15
S19
S24
S30
S37
S20
S25
S16
S31
S38
S26
S21
S32
S39
S27
S33
S40
S41
S34
S42
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Result
New Pagoda 44 seconds
7200 x 9 / 2046 32 seconds
7200 x 10 / 2046 21.4 seconds
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(No Transcript)
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4096 channels
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Restricting the client bandwidth
1/230
S566 1/(566100-1-230) 1/435 (needs to be
repeated at least once every 435 slots)
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Channel based heuristic distribution (CBHD)

• A dynamic broadcasting protocol
• Reducing the bandwidth requirements
• All customers need to wait for a fixed time
  interval w md, where m is some integer m 1
• Segment Si need to be repeated at least once
  every mi-1 slots

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How many segments?
1
C1
S1 1/m (needs to be repeated at least once
every m slots)
Repeat m segments 1/m
S1, S2, , Sm
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How many segments?
1
C2
Sm1 1/(m1m-1) 1/2m (needs to be repeated
at least once every 2m slots)
Repeat 2m segments 1/2m
Sm1, Sm2, , S3m
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CBHD

• Channel i will be assigned segments
• S(si-1-1)m1 to S(si-1)m
• Allocating k channels to a video will allow us to
  partition a video into (2k-1)m segments.

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Algorithm
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If m 1, k 4
C1
1
1
C2
2
3
2
3
C3
4
6
5
7
4
6
5
7
C4
8
10
12
14
9
13
15
8
11
9
24
K 7 channels
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Conclusion

• FDPB make all customers to wait for the same
  amount of time before watching the video.
• FDPB provides the lowest waiting times of all
  protocol using segments of equal duration and
  channels of equal bandwidth.
• CBHD proposed a dynamic protocol to saving the
  bandwidth.