Fountain Coding-based Fountain Coding-based Video Transmission System Video Transmission System
over Heterogeneous Wireless Networksover Heterogeneous Wireless Networks
Presented by
Hyunchul Joo
POSTECH
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ContentsContents
Introduction
Proposed Video Transmission System
Experiment Results
Demo
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Many wireless networks with different featuresWLAN networks
Cover small area but support high transmission rate
UMTS networks Cover wide area but support low transmission rate
IntroductionIntroduction
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IntroductionIntroduction
Vertical handoffSwitching technology between different networks to support seamless
service
MN can only access the single network at a time
Needs sophisticated architecture and mutual agreement among network
service providers
Some transition time is inevitable
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IntroductionIntroduction
Path diversityMN establishes multiple paths over multiple wireless networks
AdvantagesParallel transmission
Increase the total bandwidth Disperse the network load
Eliminate the vertical handoff delay Without the cost of cooperation on the network infrastructures
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IntroductionIntroduction
We assume that UDP (User Datagram Protocol) has to be used for
delay sensitive video streaming
The distortion caused by packet loss is more severe than source
encoding rate decreaseThe network path with high packet loss rate is useless until we deploy FEC
(Forward Error Correction) coding such as the fountain code
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Proposed SystemProposed System
Fountain CodeRateless & Erasure code
Generate endless encoded symbols from finite source symbols If a sufficient number of encoded symbols are available, all source symbols
can be recovered although some encoded symbols are lost
Type Online code LT code Raptor code Etc..
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The original data have to be divided into source blocksThe basic unit of fountain coding
Source block size = GOPOne source block impair can affect one more GOPs if the source block is not
synchronized with one GOP
Each source block is divided into source symbols and then applied
to the fountain encoding
Proposed SystemProposed System
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Based on the feedback of receiver, the transmission rate of each
path and the fountain code rate are dynamically determined to
maximize video encoding rate subject to delay and source block
loss constraints
Simple weighted round-robin scheduling is enough to distribute
packets among possible paths because all packets has the same
priority
Proposed SystemProposed System
BW, delay, PLR
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Experiment set-up802.11b and 802.11g networks are used as access technology for each
path
The JM reference software of H.264/AVC and original JM rate control
mechanism are used
CIF format HARBOUR video sequence is adopted as the test sequence The GOP structure is IPPPPPPPPPPPPPP and the number
of frames in a GOP is set to 15
Experiment ResultsExperiment Results
Sender Swi t ch Recei ver
802.11b
802.11g
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Experiment ResultsExperiment Results
The number of successfully received packetsThe number of received packets through proposed system are always
higher than K’
Performance of the proposed system is superior to other cases that
utilize the single path
GOP number
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Experiment ResultsExperiment Results
PSNR comparisonIn RS code systems
When the single reliable path is used, decoding is always successful with
low PSNR value When two paths is used, decoding is sometimes incomplete
Proposed system can provide the smooth video with high quality
because source symbols are always decoded with high PSNR value
GOP number
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Test-bed overall structureJava is used to implement the proposed system
DemoDemo
...
WLAN
HSDPA
HSDPA Modem Manager
WLAN AdapterHSDPA Adapter
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DemoDemo