SVC-Based Multisource Streaming for Robust Video Transmission in Mobile Ad-Hoc Networks Thomas Schierl, Karsten Ganger, Cornelius Hellge, and Thomas Wiegand

SVC-Based Multisource Streaming for

Robust Video Transmission in Mobile Ad-Hoc Networks

Thomas Schierl, Karsten Ganger, Cornelius Hellge, and Thomas Wiegand

IEEE Wireless Communications, October 2006.

Outline

• Introduction• Multisource Streaming Components

– Real-Time Media Delivery in MANETs– Scalable Video Coding (SVC)– Raptor Error Correction Codes

• Multisource Streaming in MANETs– Media and Channel Coding– Application Layer Protocol for Multisource Media Delivery

• Simulation Results • Conclusion

Introduction

Introduction

• Wireless LAN (WLAN):– 802.11a, 802.11b, 802.11g

Introduction

• Mobile Ad Hoc Networks (MANETs):

ClientSource A

Source ESource D

Source C

Source B

Introduction

• However, MANETs’ challenge:– High-quality video transmission

• Due to high path-outage probability.

• Therefore, this work proposed:– Robust multisource video streaming protocol

• Mainly solves the route-loss problem in case of real-time streaming over MANETs.

• By using different sources at the same time with different, independent representations of the media layers.

Introduction

• Scalable Video Coding (SVC):– SVC provides layers with different importance for t

he video reconstruction and different percentage of the complete stream bit-rate.

• Unequal Packet-Loss Protection scheme:– Protects different layers with different importance.– Based on Raptor Codes.

• Generates virtually infinite amount of encoding symbols (ESs) from a certain number of source symbols (SSs).

Multisource Streaming Components

Real-Time Media Delivery in MANETs

• In MANETs, each nodes operates as– a data-generating nodes


• In MANETs, each nodes operates as– a data-consuming nodes

• In MANETs, each nodes operates as– a router


• MANETs’ time-variant behavior– The sporadic participation of individual nodes in th

e network.



• MANETs routing algorithm: Proactive & Reactive.

• In this works:– Reactive routing algorithms:

• Initiate a routing query only if a packet is to be transmitted to a destination for which it has no active entry in the routing table.

• Reduce routing overhead, but might also add some delay.

• Dynamic MANET on-demand (DYMO) [8].[8] I. Chakeres, E. Belding-Royer, and C. Perkins, “Dynamic MANET On-demand (DYMO) Routing,” draft version 04, IETF, Mar. 2006.

• Mobile multihop Ad-Hoc network in client-server setup


Scalable Video Coding (SVC)

• SVC is an extension to the H.264/MPEG4-AVC video coding standard.– To extend the wide range of:

• Temporal Scalability.• Spatial Scalability.• Quality Scalability.

• An SVC bit-stream consists of a base layer and several enhancement layers.– The base layer is a plain H.264/MPEG4-AVC bit-

stream for backward compatibility.


Spatial decimation

Temporal scalable coding

Temporal scalable coding

Prediction

Prediction

Base layer coding

Base layer coding

SNR scalable coding

SNR scalable coding

Scalable bit-stream

Base Layer

Enhancement Layer


• Temporal Structure of an SVC stream including Progressive Refinement (PR).


• SNR Scalability (Quality Scalability):– The enhancement layers contain

refinement quality information of the base layer in a progressive way.

Raptor Error Correction Codes

• Raptor Code: – Mainly used in environments with packet losses.– Can produce virtually infinite amount of encoding

symbols from a vector of source symbols SV of the length k.

– Decoder is capable of reconstructing the source symbols from a number of ES that is only slightly higher than the original length of the SV.

– Can be viewed as a serial concatenation of a pre-code and LT Code.


5

4

3

2

1

5

4

3

2

1

ES

ES

ES

ES

ES

E

D

C

B

A

ψ

ψ

ψ

ψ

ψ

1 :ψ where, i k

LT Code

Source symbol


A B C D

E

1 2 3

65

4

‧Modified Inverse Tree-based UEPLT Encoding Graph

6

5

4

3

2

1

ES

ES

ES

ES

ES

ES

EDC

EBA

D

C

B

A

E

D

C

B

A

11100

10011

01000

00100

00010

00001Ψ1


[10] 3GPP TS 26.346 V6.4.0, “Technical Specification Group Services and System Aspects; Multimedia Broadcast/Multicast Service (MBMS); Protocols and Codecs,” Mar. 2006.

Raptor Code

) (1 :ψ where, i sk

5

4

3

2

1

5

4

3

2

1

ES

ES

ES

ES

ES

0

0

0

Z

Y

X

E

D

C

B

A

ψ

ψ

ψ

ψ

ψ

10001011

01010110

00101101

I3x3Pre-code: Gp [10]

LT Code: GLT

Source symbol

Parity-Check symbol

Z

Y

X

E

D

C

B

A

01011

10110

01101

Parity-Check symbol:

Pre-code: Gp [10]

Multisource Streaming In MANETs

Media and Channel Coding

Layer 2

nl Raptor encoded symbols

Layer 3

Layer 1

tSB

Source block SB with kl symbols per layer l

1

1

1 k1

k2

k3 …

…

…

Source 1

Source 3

Source 2

Sending nls symbols

Client

Multisource transport:


Layer 3

Layer 2Layer 1

nl Raptor encoded symbols

tSB

Source block SB with kl symbols per layer l

1

1

1 k1

k2

k3 …

…

…

layer byte-rate:SBt

Tnr l

sls

tl

transmission rate:

SBt

Tkr ll

l

code rate:L

lL

k

nr

l

sl

cl

1

SBSB

1

t

Tk

L

lL

t

Tk

k

nrrr llll

l

sl

lcls

tl

l

sl k

L

lLn

1333

222

111

3

1

3

1333

2

3

123

1 3

113

kkn

kkn

kkn

s

s

s


• Client behavior:– Client can influence the number of received sy

mbols per layer, by selecting the number of sources.

– Decoding is successful if the number of source symbols per layer l used for encoding is equal or higher than the minimal number of symbols kmin specified in [10].


Media and Channel Coding• The different sources are using different random se

eds i for generating Ψi for the encoding process.– Ensures the generation of independent ESs for each source stre

am.

Source 3:

EDC

EBA

E

D

C

B

A

11100

10011

Source 2:

D

C

E

D

C

B

A

01000

00100

Source 1:

B

A

E

D

C

B

A

00010

00001

Application Layer Protocol for

Multisource Media Delivery

route loss probability for a path going via M intermediate links: Mlr pP )1(1

2)1(1 lr pP


Multisource Media Delivery• The proposed concept:

– To increase the number of used sources for enhancing reliability in server availability, while keeping the overall used network transmission rate as small as possible.

• The authors assume that:– Nodes are not running in congestion state

at any time.• The transmission rate at an intermediate,

source, or client node is not higher than the available transmission rate provides by the air interface.


Multisource Media Delivery• The authors further assume that:

– The overall probability of having a route from at least one source out of S sources to the client being Pc

with having independent network paths per source. – Every source route has the same route-loss

probability: Pr

sSr

Sr

S

sc PP

s

SP

)()1(

1

s cP1555

1

)()1(1

5

rr

sc PPP


Multisource Media Delivery• The protocol for source monitoring and

selection probes available sources cyclically.– The authors assume that the addresses of source

nodes available in the Ad-Hoc network area are introduced by an external instance.

• Which is not consider in this work.

– The monitoring of sources is achieved by sending probing packets (inquiry packets) to all known sources for collecting path quality in formation per source.

• Sources are probed continuously during media transmission.


Multisource Media Delivery• Metric information:

– The link/route quality information collected by the inquiry process.

– The multisource coded network streams are requested from nodes with the best metric.

– The metric used is the distance from client to the source node in terms of hops.

• Motivated by equation for Pr (route loss probability), • The more nodes are used within a path, the higher

the probability is the route may break down.


Multisource Media Delivery• Simplified client scheme for frequent server

evaluation:

＊ The protocol has been implemented and executed in ns-2.


Multisource Media Delivery• Stream management with resulting layered video quality:

Simulation Results

Simulation Results

• Operation points of SVC/Single-layer media stream:– A repeated Paris sequence (288 frames) with 8640

frames (285 sec), 30 frames per second, CIF resolution, GOP size 32.

Simulation Results

• Environment:– Area: 1000 x 600m

– 40 nodes (moving in random waypoint patterns)

• Scenario:– 1 client and 1, 2, 3, 4, 8, and 12 available and randomly

selected source nodes.

– Each simulation is repeated 60 times in independent random waypoint.

– An overall simulation time of 4.75 h per value of available source nodes.

Simulation Results

• For Raptor encoding, 3GPP-recommended preconditions [10] is adopted.

• DYMO [8] is used as routing protocol in combination with an IEEE 802.11b adapter.

• The average FEC stream rate is approximately 594 kb/s.

• Due to packetization overhead, the effective FEC protection rate:– Multisource coded stream: 84.19 % – Single-layer stream: 86.30 %

[8] I. Chakeres, E. Belding-Royer, and C. Perkins, “Dynamic MANET On-demand (DYMO) Routing,” draft version 04, IETF, Mar. 2006.


Simulation Results

• Average results for single-source and multisource modes.

1

Conclusion

Conclusion

• Presented an extended unequal packet-loss protection (UPLP) scheme based on Raptor FEC using different sources for reliable media streaming in MANETs.

• Showed the benefits of using linear independent FEC streams with unequal loss protection for multisource streaming in scenarios with high route-loss probability, as is present in MANETs.

• This approach has been evaluated with a new protocol for media tracking and delivery in MANETs, which exclusively relies on application layer techniques.

Thank you

Documents

SVC-Based Multisource Streaming for Robust Video Transmission in Mobile Ad-Hoc Networks Thomas Schierl, Karsten Ganger, Cornelius Hellge, and Thomas Wiegand