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An adaptive video multicast scheme for varying workloads. Kien A.Hua, JungHwan Oh, Khanh Vu Multimedia Systems, Springer-Verlag 2002. Outline. Introduction Related Work Proposed Approach Performance Model Performance Conclusion. Introduction.

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An adaptive video multicast scheme for varying workloads

An adaptive video multicast scheme for varying workloads

Kien A.Hua, JungHwan Oh, Khanh Vu

Multimedia Systems, Springer-Verlag 2002


Outline
Outline

  • Introduction

  • Related Work

  • Proposed Approach

  • Performance Model

  • Performance

  • Conclusion


Introduction
Introduction

  • Maximize the efficiency of server resource with

    • Periodic broadcast

    • Scheduled Multicast (batching)

    • Hybrid Design

  • Will show that existing scheduled multicast techniques are not suited for hybrid designs


Related work skyscraper broadcasting scheme
Related WorkSkyscraper Broadcasting Scheme

  • Fragmentation recursive function

    • Series [1,2,2,5,5,12,12,25,25,52,52,…]


Related work skyscraper broadcasting scheme1
Related WorkSkyscraper Broadcasting Scheme

22-mins video

5 min buffer

Apply aforementioned series function => segment size = 10.4 !!

1.5 Mbits/sec

0.5 min latency


Related work scheduled multicast
Related Work Scheduled Multicast

  • Differ primarily in the criterion used to select which batch will receive service

    • First come, first served (FCFS)

    • Maximum queue length first (MQL)

    • Maximum factored queue length first (MFQ)


Related work scheduled multicast1
Related Work Scheduled Multicast

  • FCFS

  • MQL

Video 1

time

Video 2

time

Fair , maybe bad throughput

Video 1

time

time

Video 2

Better throughput, maybe not fair


Related work maximum factored queue length first mfq
Related WorkMaximum factored queue length first (MFQ)

  • Applying a discriminatory weighting factor to the length of the queue

  • : video i length, : the request frequency of video i

  • Schedule video with the largest value of


Related work maximum factored queue length first mfq1
Related WorkMaximum factored queue length first (MFQ)

  • d

  • d

Still not fair, because not average waiting time !!


Proposed approach
Proposed Approach

  • Adaptive Hybrid Approach (AHA)

    • With a novel scheduled multicast --

      “Largest aggregated waiting time first scheme” (LAW)

    • And SB (skyscraper broadcast)


: the total number of pending requests for video i

: the arrival time of the jth request for video i

c : the current time

LAW

  • Compare with MQL, it take account of the distribution of the request

    • With considering “aggregated waiting time”


LAW

Compute the sum of video i service latency

S1=128*5-(107+111+115+121+126)=60

S1=128*5-(107+111+115+121+126)=60

S2=128*4-(112+119+122+127)=32


Adaptive hybrid approach
Adaptive hybrid approach

  • With following procedures to decide which videos to broadcast



Performance model
Performance model

  • Compare AHA with MFQ-SB-n

  • Performance metrics

    • Defection rate

    • Unfairness

    • Average service latency

    • Throughput

  • 100 videos, each 120 mins,

    avg. playback rate 1.5 Mbits/sec.



Performance law vs mfq
Performance - LAW vs. MFQ

LAW perform slightly

better than MFQ

in service latency,

throughput, defection rate

Arrival rate : 8 req/min

Skew factor : 0.3



Performance1
Performance

  • Compare MFQ-SB-n with altering one of

    • Server Capacity (channels)

    • Request Arrival Rate

    • Skew Factor






Conclusion
Conclusion

  • Prove that existing scheduled multicast schemes are not suited for hybrid design

  • Proposed a new technique called Largest Aggregated Waiting time first (LAW)

  • AHA is capable of coping with a changing workload


Periodic broadcast 1996
Periodic Broadcast (1996)

  • PB v.s. batch:

    • Short initial delay

    • Large client-side buffer

video

Client requests

time


Batching 1993
Batching (1993)

  • Batch window:

    • The time interval to initiate a batch stream.

0

t1

t2

t3

time

Client requests




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