Topic 4: Incentive Techniques
N. Ben Salem and J.-P. Hubaux
Related Work
Selfishness in ad hoc networks
•
S. Marti, T.J. Giuli, K. Lai, and M. Baker, “Mitigating Routing Misbehavior in
Mobile Ad Hoc Networks,” in Proceedings of Mobicom 2000.
•
L. Buttyan and J. P. Hubaux, “Enforcing Service Availability in Mobile Ad Hoc
WANs,” in Proceedings of MobiHoc 2000.
•
L. Buttyan and J. P. Hubaux, “Stimulating cooperation in self-organizing
mobile ad hoc networks,” ACM/Kluwer Mobile Networks and Applications
(MONET), October 2003
•
S. Zhong, Y. R. Yang, and J. Chen, “Sprite: A Simple, Cheat-Proof, CreditBased System for Mobile Ad Hoc Networks,” in Proceedings of INFOCOM
2003.
•
P. Michiardi and R.Molva, “Core: A COllaborative REputation mechanism to
enforce node cooperation in Mobile Ad Hoc Networks,” in Proceedings of The
6th IFIP Communications and Multimedia Security Conference 2002.
•
S. Buchegger and J. Y. Le Boudec, “Performance Analysis of the CONFIDANT
Protocol: Cooperation Of Nodes — Fairness In Distributed Ad Hoc
NeTworks,” in Proceedings of MobiHoc 2002.
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Related Work
Selfishness in hybrid ad hoc networks
•
M. Jakobsson, J.-P. Hubaux and L. Buttyan, "A Micro-Payment Scheme
Encouraging Collaboration in Multi-Hop Cellular Networks", in Proceedings
of FC 2003.
•
N. Ben Salem, L. Buttyán, J.-P. Hubaux and M. Jakobsson, "A Charging and
Rewarding Scheme for Packet Forwarding in Multi-hop Cellular
Networks", Technical Report No. IC/2003/55, Swiss Federal Institute of
Technology (EPFL), Lausanne, September 2003.
•
B. Lamparter, K. Paul and D. Westhoff, "Charging Support for Ad Hoc Stub
Networks", Journal of Computer Communication,Special Issue on Internet
Pricing and Charging, Algorithms, Technology and Applications,Elsevier
Science ,Summer 2003.
Selfishness in WiFi networks
•
N. Ben Salem, J.-P. Hubaux and M. Jakobsson, "Reputation-based Wi-Fi
Deployment: Protocols and Security Analysis", WMASH'04, Philadelphia,
USA, October 2004
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Outline
Part 1 : Incentive to cooperate in pure Ad Hoc Networks
1.1 - The Nuglets Approach
1.2 - Sprite: A Simple, Cheat-Proof, Credit-based System for
Mobile Ad Hoc Networks
Part 2 : Incentive to cooperate in Hybrid Ad Hoc Networks
2.1 - A Micro-Payment Scheme Encouraging Collaboration in
Hybrid Ad hoc Networks
2.2 - A Charging and Rewarding Scheme for Packet Forwarding
in Hybrid Ad hoc Networks
Part 3 : Incentive to cooperate in WiFi Networks
Reputation-based WiFi Deployment: Protocols and Security Analysis
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Part 1
Incentive to cooperate in pure Ad Hoc Networks
1.1-The Nuglets Approach
L. Buttyán and J.-P. Hubaux
Motivation and goal
Ad hoc networks
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•
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no infrastructure
all networking services are provided by the nodes themselves
cooperation is essential
Problem
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assume that nodes don’t belong to a single authority
there’s no good reason to cooperate
nodes tend to be selfish
Example
if the average number of hops from source to destination is ~5
Æ ~80 % of the energy is devoted to packet forwarding
Æ temptation to deny packet forwarding is strong
Our goal: to design a mechanism that stimulates cooperation
(packet forwarding)
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Proposed stimulation mechanism
Each node has a credit counter c, and
1. when sending an own packet
– the number n of needed intermediate forwarding nodes is estimated
– if c < n, then the packet cannot be sent
– otherwise, the packet can be sent, in which case c is decreased by n
2. when forwarding a packet
– c is increased by 1
+ Protection that ensures that
– the user cannot manipulate the credit counter
– the user cannot tamper with the above mechanism (but she can decide
to drop a packet before the mechanism is called !)
– c is increased only if the packet has indeed been forwarded
• We propose a protection mechanism that is based on a tamper
resistant hardware module in each node
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Single node model (basic)
B, C, N
INo
b, c
INf
DRP = DRPo + DRPf
OUT = OUTo + OUTf
B – initial battery level
C – initial credit level
N – constant charge
b – battery
c – credit counter
outo – own packets sent
(during whole lifetime)
outf – forwarding packets sent
(during whole lifetime)
Selfishness:
maximize outo subject to
(1)
(2)
(3)
outo, outf
≥ 0
N outo – outf ≤ C
outo + outf = B
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Single node model (extended)
- own packets are generated at rate ro
- forwarding packets arrive at rate rf
- no buffering (if an own packet cannot be sent due to the low level of
the credit counter, then it is dropped)
tend – time when the battery is drained out (not a constant! )
zo = outo / ro tend – fraction of own packets sent
Selfishness:
maximize outo and zo subject to
(1)
(2)
(3)
(4)
(5)
outo, outf ≥ 0
outo ≤ ro tend
outf ≤ rf tend
N outo – outf ≤ C
outo + outf = B
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Forwarding rules
If f = (NB – C)/(N + 1) then drop else
– rule 1: always forward
– rule 2: if c ≤ C then forward else forward with prob C /c
– rule 3: if c ≤ C then forward else drop
– rule 4: if c ≤ C then forward with prob c /C else drop
where f is the number of packets forwarded so far and c is the current
credit level
Prfwd(c)
1
rule 1
C
Prfwd(c)
1
c
rule 3
C
Prfwd(c)
1
c
rule 2
C
c
rule 4
Prfwd(c)
1
C
c
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Comparison of forwarding rules (1)
Simulation parameters
B = 100000 ro = 0.2 pkt/s
C = 100
rf = 0.6 … 1.6 pkt/s
N=5
Simulation results
outo = 16683 = (B + C )/(N + 1)
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Comparison of forwarding rules (2)
Simulation parameters
space
number of nodes
power range
mobility model
speed
avg. pause time
500 m x 500 m
100
120 m
random waypoint
1 m/s – 3 m/s
60 s
pkt generation rate
choice of pkt. dest.
routing
initial credits
credit sync interval
simulation time
0.2 (0.5, 0.8) pkt/s
random
geodesic pkt fwding
100
5 (10, 15, 20) s
7200 s
Simulation results
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Throughput
The effect of less cooperative nodes (rule 3) on the total cumulative throughput
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Conclusion
• We proposed a mechanism to stimulate the nodes of an ad hoc
network for packet forwarding
• Our approach is based on a credit counter and enforcement of some
simple rules in each node (tamper resistant hardware)
• We showed that the mechanism is effective assuming the following:
– each node generates packets continuously
– own packets are not buffered (they must be sent immediately or dropped)
– selfishness is represented by the goal of dropping as few own packets as
possible
Future work
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Weakening the above assumptions
Application to other network functions (not only packet fwding)
Application in higher layers (e.g., peer-to-peer systems)
Application in hybrid ad hoc networks
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