Analytical Model of Hop-to-End based Network-Adaptive FEC scheme over

Multi-hop Wireless Networks

2010.3.18

Koh Choi

Networked Media LaboratoryDept. of Information & Communications

Gwangju Institute of Science & Technology (GIST)

1

2

Introduction(1/2)

Video streaming in Multi-hop Wireless Networks Burst packet loss, long delay Decreased streaming quality

FEC-based error control Reduce packet loss and support streaming quality Limitation of traditional FEC scheme

End-to-End(E2E) FEC: self-induced congestion problem, long packet delay Hop-by-Hop(HbH) FEC: per-hop overhead, additional complexity

Sender

Receiver

...Traffic streams

...

Video streaming over Multi-hop Wireless Networks

…Tim

e

PlaybackBuffer

Packet loss Packet discard

3

Introduction(2/2)

Proposed Multi-hop FEC scheme Combine E2E and HbH FEC scheme Partitioning, overlay …

Hop-to-End FEC scheme Multi-hop FEC scheme Adaptive control from hop to end concept Minimize packet loss and considering delay-constraint

Reduce less delay than E2E FEC and HbH FEC

To apply Hop-to-End FEC scheme,it need adaptation policy over multi-hop wireless

networks from monitored results.Also, it support guideline based on adaptation policy.

In this presentation, design adaptation policy through analytical modeling aspect as coordinator to control

adaptive FEC control.

4

Problem Definition

Objective Minimize recovered packet loss (P(n,k,x))

Constraints Delay constraint: D(n,k,x) ≤ DC

Bandwidth limitation: Bfec(n) ≤ Bmax(Breq(n-k) ≤ Bavail) Fixed sending rate of streaming data: R Fixed original data: k

Monitoring parameter Pe2e, Phop(x), Ph2e(x), De2e, Dhop(x), Dh2e(x) Monitoring main component: Phop(x), Dhop(x)

Control parameter FEC symbol size n, FEC Operation Point

5

System Model(1/2)

Video Server Video Receiver

(Pe2e, De2e)

Phop(1), Dhop(1) Phop(2), Dhop(2) Phop(3), Dhop(3) Phop(4), Dhop(4) Phop(5), Dhop(5)

L

iihopee PP

1)(2 )1(1

n

ki

inee

ieekneer PP

i

nP 22),(2 )1(

L

xiihopxeh PP )1(1 )()(2

n

ki

inxeh

ixehxknehr PP

i

nP )(2)(2),,(2 )1(

)()()()( kdatakdatakdatanredun Bk

knBB

k

nB

End-to-End FEC

Hop-to-End FEC

Only consider narrow bandwidth in streaming path.

6

System Model(2/2)

Video Server Video Receiver

(Pe2e, De2e)

Phop(1), Dhop(1) Phop(2), Dhop(2) Phop(3), Dhop(3) Phop(4), Dhop(4) Phop(5), Dhop(5)

L

ixhopee DD

1)(2

),(),(2),,(2 )1( knfecknfeceexkneer DTETDD

L

xixhopxeh DD )()(2

),(),()(2),,(2 )1( knfecknfecxehxknehr DTETDD

End-to-End

Hop-to-End

Additional delay factor from increasing hop count and data rate

(offline measure)

7

AM-H2E(TBD) Modeling

1

1),,(2)(

....1),,( ))1)(1(1(min

x

ixknehrihop

Lxxkn PPP

availknredun BB )(

Cxknehr

x

iihopxkn DDDD

),,(2

1

1)(),,(

Input (k, Phop(x), Dhop(x)) Output

(n, x)

Original data k is fixed. Based on above formulation, find (n, x).

8

Notation-Pe2e: End-to-End(E2E) packet loss-Phop(x): Hop-by-Hop(HbH) packet loss-Ph2e(x): Hop-to-End(H2E) packet loss-Pr-e2e(n,k): Recovered E2E packet loss-Pr-hop(n,k,x): Recovered HbH packet loss-Pr-h2e(n,k,x): Recovered H2E packet loss-P(n,k,x): Total recovered packet loss-De2e: E2E transmission delay-Dhop(x): HbH transmission delay-Dh2e(x): H2E transmission delay-Dr-e2e(n,k): Recovered E2E transmission delay-Dr-hop(n,k,x): Recovered HbH transmission delay-Dr-h2e(n,k,x): Recovered H2E transmission delay-D(n,k,x): Total recovered transmission delay

-R(k): Original sending rate-R(n): Sending rate with redundant data-P: Packet size-M: Number of nodes-L: Number of hops-Bmax: Maximum Bandwidth-Bavail: Available Bandwidth (Bmax – Bdata)-Bdata(k): Original data bandwidth-Bredun(n-k): FEC bandwidth from redundant data-Bfec(n,k): Overall bandwidth(Breq + Bdata)-FOP(x): FEC Operation Point-Dc: Delay constraint-Pc: Covered packet loss-ETfec(n,k): Encoding time-DTfec(n,k): Decoding time-DR(n): Transmission delay from sending rate

9

Implementation progress

ReceivingSending

Buffering

Module interface

Recv- thread Send- thread

Base Hop-agent

Transport Layer

Plugable Module

Enqueue Interface

Dequeue Interface

Agent-queue

Monitoring module PureQueue

FEC

Enable FEC code based on RS Using NASTE+ FEC code Modified FEC operation (exclude unnecessary operation)

Define interface Monitoring parameter, module and enqueue/dequeue interface