Juan-Antonio CorderoPhilippe JacquetEmmanuel Baccelli Orlando, FL -- March 29 th, 2012 Impact of...

Juan-Antonio Cordero Philippe Jacquet Emmanuel Baccelli

Orlando, FL -- March 29th, 2012

Impact of Jitter-based Techniques on Flooding over Wireless Ad hoc Networks

Model and Analysis

31st Annual IEEE International Conference on Computer Communications

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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding

Motivation: Flooding over wireless ad hoc networks

Packet collisions in wireless flooding

The jitter technique for flooding

Framework: goals, assumptions, approach

Main results

Discussion

Agenda

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Motivation

Flooding in Wireless Ad hoc Networks

Flooding

Periodic dissemination of messages over the network

Routers participating in flooding:

1) Create and transmit their own messages

2) Receive and forward messages from other routers in the network

Example:

Link-state routing: OSPF, OLSR Other…

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Motivation

Wireless Ad hoc Networks

Wireless communication

Dynamic and unpredictably changing topology

Less available bandwidth

More updates required (in routing protocols)

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Motivation

Wireless Ad hoc Networks

Wireless communication

Dynamic and unpredictably changing topology

Less available bandwidth

More updates required (in routing protocols)

Packet collisions in flooding !

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A tx

Shared channel(from D)

A

BB rx

processing

B tx

CC rx

processing

C tx

systematic collision

Wireless flooding : Stating the problem A

B

C

D

Wireless flooding

Packet collisions in flooding

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Wireless flooding with jitter | Intuition

A tx

Shared channel(from D)

A

BB rx

processing

B tx

CC rx

processing

C tx

random delay for C tx

random delay for B tx

The jitter technique

Jitter for flooding

A

B

C

D

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Packet piggybacking

Wireless flooding with jitter : RFC 5148

Self-generated msg at t=t1

Received pkt at t=t0

Assigns a jitter value jto all msgs of the pkt

N=1

Extracts N-thmsg from the pkt

N-th msg needs to be forwarded?

Schedule txat t=t0+j

Scheduled tx at t=t2

Next N?

Send all msgs scheduled and not sent at t=t2

Schedule txat t=t1

t2=t1

Yes

Yes

No

No

The jitter technique

Jitter for flooding

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Advantages

Reduction of systematic packet collisions by spreading transmissions

Reduction in the number of transmissions due to piggybacking

Drawbacks

Delay of the flooding operation

Increase of the length of the transmitted packets

Impact of jitter technique in wireless flooding

Main effects

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System model

Packet arrival ~ punctual, homogeneous Poisson process

Instantaneous packet transmission

All packets received are to be forwarded

R

In λin

Self-generatedλg

Outλout


Model and assumptions

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time(in)

Arrival triggering a collecting phase


Variables

t

t0

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time(in) (in) (in)

…

(in)



Variables

t

t1

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time(in) (in) (in) (self)

…

(in)

D(t) ≡ avg length of collecting phase

t


Effective time of transmission


Variables

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Average duration of collecting phase

ODE )('))(()('' tDtFtD gTin j

t x

gTin yFdydxtDj

0 0

)(exp)( General solution ( D(0) = 0 ; D’(0) = 1 )

Out-packet rate}{1 Dtin

ginout E

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time(in) (in) (in) (self)

…

(in)

t


Effective time of transmission


Variables

G(t)

Ttx(t)

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In-packet delays

Average in-packet cumulated delay before out-packet transmission

where

Average forwarding delay for an in-packet

)()()( tHtDtG

)(1

)()(

tD

tGtT

intx

t

Tin dxtFtDtHj0

))(1()(')('

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Some particular results

Uniformly distributed jitter ( RFC 5148 )

Packet delays: D(t) , Ttx(t)

Packet rate: λout(λin, λg) , λout(T)

Jm

1/Jm

pdf Tj

Jm

1

cdf Tj

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Delays before transmission

Ttx(t) ≡ Avg time of transmission D(t) ≡ Avg duration of collecting phase

(λin = 4 pkt/sec, λg = 0.2 pkt/sec, Jm = 1 sec)

Model results

D(t)

Ttx(t)

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Out-packet rate

λout ≡ Out-packet rate (pkts/sec)

(Jm = 1 sec)

λg = 0

λg = 0.9

Model results

λout

λin +λg

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λout ≡ Out-packet rate (pkts/sec)

( λ in = 4 pkts/sec, λg = 0.2 pkts/sec )


Out-packet rate Model results

with simulations

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Discussion & Conclusions

Future work

Non-instantaneous packet transmissions ( packet collisions)

More jitter … less collisions ?

Network experimental results

RFC 5148 : jitter + piggybacking for flooding (OLSR, OSPF, DYMO…)

Theoretical model : additional delay D(t) vs. packet rate (λout) reduction

Generality of results

Model limitations

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Questions ?

E-mail: [email protected]

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Backup slides

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dtdttDdtdtdtD

dxxDxftDtTPdttD

ging

t

Tjin j

)()(1)(

)()()()()(0

Transition equations for D(t) and F(t)

)()(10

)()()()()(0

tFdtdt

dxxGxftGtTPdtdttF

ging

t

Tjin j

Avg duration of collecting phase

Avg cumulative delay of in-packets arrived within a collecting phase

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Some values…

Jitter scale (Friedman, Hay & Kliot, 2009)

For Jm = t = 10 msec, λin = 15 pkt/sec, λg = 0,25 pkt/sec,

λout = 14,2 pkt/sec (-7%)

D(t) = 9,74 msec, Ttx(t) = 8,92 msec (worst case)

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References

(Technical Report, 2009) R. Friedman; D. Hay; G. Kliot: Jittering Broadcast Transmissions in MANETs: Quantification and Implementation Strategies. Department of Computer Science, Technion – Institute of Technology of Israel.

(Journal, 2004) C. Adjih; E. Baccelli; T. Clausen; P. Jacquet; G. Rodolakis: Fish Eye OLSR Scaling Properties. In: IEEE Journal of Communications and Networks (JCN), Special Issue on Mobile Ad Hoc Wireless Networks, Volume 6, Number 4, pp. 343-351, IEEE, December 2004.

(Conference, 2003) T. Henderson et al.: A Wireless Interface Type for OSPF, Proceedings of the IEEE Military Communications Conference (MILCOM), pp. 137-145, Boston, MA (United States), October 2003.

(Conference, 1998) J. Broch; D. A. Maltz; D. B. Johnson; Y.-C. Hu; J. Jetcheva: A performance comparison of multi-hop wireless ad hoc network routing protocols, Proc. ACM Annual International Conference on Mobile Computing and Networking (MobiCom’98), pp. 85–97, Dallas, TX (United States), October 1998.

Juan-Antonio CorderoPhilippe JacquetEmmanuel Baccelli Orlando, FL -- March 29 th, 2012 Impact of...

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