juan-antonio corderophilippe jacquetemmanuel baccelli orlando, fl -- march 29 th, 2012 impact of...
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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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
System model
Packet arrival ~ punctual, homogeneous Poisson process
Instantaneous packet transmission
All packets received are to be forwarded
R
In λin
Self-generatedλg
Outλout
Impact of jitter technique in wireless flooding
Model and assumptions
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
time(in)
Arrival triggering a collecting phase
Impact of jitter technique in wireless flooding
Variables
t
t0
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
time(in) (in) (in)
…
(in)
Arrival triggering a collecting phase
Impact of jitter technique in wireless flooding
Variables
t
t1
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
time(in) (in) (in) (self)
…
(in)
D(t) ≡ avg length of collecting phase
t
Arrival triggering a collecting phase
Effective time of transmission
Impact of jitter technique in wireless flooding
Variables
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Impact of jitter technique in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
time(in) (in) (in) (self)
…
(in)
t
Arrival triggering a collecting phase
Effective time of transmission
Impact of jitter technique in wireless flooding
Variables
G(t)
Ttx(t)
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Impact of jitter technique in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Impact of jitter technique in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Impact of jitter technique in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Impact of jitter technique in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
λout ≡ Out-packet rate (pkts/sec)
( λ in = 4 pkts/sec, λg = 0.2 pkts/sec )
Impact of jitter technique in wireless flooding
Out-packet rate Model results
with simulations
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Questions ?
E-mail: [email protected]
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
Backup slides
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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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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Link-state routing over MANETs: Estimating the impact of jitter techniques in wireless flooding
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.