1 a low bandwidth broadcasting protocol for video on demand j. paris, s. w. carter, d. d. e. long in...

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A Low Bandwidth A Low Bandwidth Broadcasting Protocol Broadcasting Protocol for Video on Demandfor Video on Demand

J. Paris,J. Paris,

S. W. Carter, D. D. E. LongS. W. Carter, D. D. E. Long

In Proceedings of ICCCN, 1998

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OutlineOutline

Harmonic-base BroadcastingHarmonic-base Broadcasting Polyharmonic BroadcastingPolyharmonic Broadcasting DiscussDiscuss ConclusionConclusion

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Harmonic Broadcasting (HB)Harmonic Broadcasting (HB)

Divide a video into Divide a video into n equally-sizedn equally-sized segmsegmententss

Each segment Si, for 1 ≤ i ≤ n, is broadcEach segment Si, for 1 ≤ i ≤ n, is broadcast repeatedly on its own channel with a ast repeatedly on its own channel with a bandwidth (b / i)bandwidth (b / i)

Unfortunately Unfortunately HB does not always deliveHB does not always deliver all data on timer all data on time

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An illustration of the first three An illustration of the first three streams for a video under streams for a video under

harmonic broadcastingharmonic broadcasting

Play Rate : b

Receive Rate : b/2

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Harmonic BroadcastingHarmonic Broadcasting

The bandwidthThe bandwidth

Where H (n) is the harmonic number of n

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Cautious Harmonic Cautious Harmonic Broadcasting (CHB)Broadcasting (CHB)

The first channel broadcasts The first channel broadcasts S1S1 repeate repeatedly as before. (bandwidth b)dly as before. (bandwidth b)

The The second channelsecond channel alternates between alternates between broadcasting broadcasting S2 and S3S2 and S3 (bandwidth b) (bandwidth b)

Then the Then the remaining n – 3 channel remaining n – 3 channel broadbroadcasting casting S4 – SnS4 – Sn. (bandwidth b/i). (bandwidth b/i)

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Cautious Harmonic Cautious Harmonic BroadcastingBroadcasting

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Cautious Harmonic Cautious Harmonic BroadcastingBroadcasting


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Quasi-harmonic BroadcastingQuasi-harmonic Broadcasting(QHB)(QHB)

The first segment is The first segment is left intactleft intact.. The remaining segments Si, for 2 ≤ i ≤ The remaining segments Si, for 2 ≤ i ≤

n, is divided up inton, is divided up into im-1 fragment im-1 fragment , for s , for some positive parameter m. ome positive parameter m.

Slots are also broken up into Slots are also broken up into m equal m equal susubslotbslotss, and each subslot can be used to , and each subslot can be used to broadcast a single fragment.broadcast a single fragment.

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Quasi-harmonic Quasi-harmonic broadcasting broadcasting

(m = 4)(m = 4)

S1 S2,1 S2,3 S2,5 S2,7 ……

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Quasi-harmonic Quasi-harmonic BroadcastingBroadcasting

The key to QHB is that the fragments are The key to QHB is that the fragments are not broadcast in order.not broadcast in order. 1) The last subslot of each slot is used to bro1) The last subslot of each slot is used to bro

adcast the first adcast the first i -1 fragmenti -1 fragment 2) the rest of the fragments are ordered suc2) the rest of the fragments are ordered suc

h that the k-th subslot of slot j is used to broh that the k-th subslot of slot j is used to broadcast fragment adcast fragment ik+j-1 mod i(m-1) +iik+j-1 mod i(m-1) +i

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Quasi-harmonic Quasi-harmonic BroadcastingBroadcasting


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Polyharmonic Broadcasting Polyharmonic Broadcasting (PHB)(PHB)

1) it requires that the client STB 1) it requires that the client STB starts dstarts downloading data from the moment a cuownloading data from the moment a customer requests a specific videostomer requests a specific video instead instead of waiting until the customer begins watof waiting until the customer begins watching the beginning of the first segment. ching the beginning of the first segment.

2) polyharmonic broadcasting 2) polyharmonic broadcasting uses a fixuses a fixed wait policy.ed wait policy.

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Polyharmonic BroadcastingPolyharmonic Broadcasting

Divide into n equal segment (D/n)Divide into n equal segment (D/n) Segment SSegment Sii at a transmission rate at a transmission rate

bbii = = b / (m + i - 1)b / (m + i - 1) No client can start consuming the first segmenNo client can start consuming the first segmen

t of the video before having downloaded data ft of the video before having downloaded data from all n streams during rom all n streams during a time interval of dura time interval of duration w = mdation w = md

Segment Si will not be consumed Segment Si will not be consumed until (m + i – until (m + i – 1 )d time units1 )d time units have elapsed. have elapsed.

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Polyharmonic BroadcastingPolyharmonic Broadcasting(m=2)(m=2)

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The BandwidthThe Bandwidth

If n = k * mIf n = k * m

Since w = md; d= D/n;

w = D/k ; k 愈大則 waiting time 愈小

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Polyharmonic BroadcastingPolyharmonic BroadcastingThe Data Receive during time slot i

The Data Consume during time slot i

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DiscussionDiscussion

First, Polyharmonic broadcasting First, Polyharmonic broadcasting requires requires m times more streamsm times more streams than than other harmonic broadcasting protocols.other harmonic broadcasting protocols.

Second, Polyharmonic broadcasting Second, Polyharmonic broadcasting forces forces all customers to wait for the all customers to wait for the maximum waiting delaymaximum waiting delay while other while other harmonic protocols only require few harmonic protocols only require few customers to wait that long.customers to wait that long.

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Bandwidth vs Average Waiting TimeBandwidth vs Average Waiting Time

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ConclusionConclusion

We have presented a new We have presented a new broadcasting protocol that provides broadcasting protocol that provides the same maximum waiting time as the same maximum waiting time as the harmonic broadcasting protocol the harmonic broadcasting protocol while consuming significantly less while consuming significantly less bandwidth.bandwidth.

But All Client must wait the same But All Client must wait the same time and the two more streamtime and the two more stream

1 a low bandwidth broadcasting protocol for video on demand j. paris, s. w. carter, d. d. e. long in...

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