Selfish Misbehavior in Wireless Networks

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Selfish Misbehavior inWireless Networks

• Nitin Vaidya
• University of Illinois at Urbana-Champaign
• www.crhc.uiuc.edu/wireless

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Increasing Wireless Deployment in Unlicensed Bands

• Hot-spots
• Community wireless networks
• Home networks
• Sensors

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Users Must Trust the Network

• Wired-equivalent privacy mechanisms
• Going beyond privacy

Users must be able to rely on fair
competition
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Unlicensed Bands
The New Wild Wild West ?

• Increasing demand
• Limited resources
• Few rules !
• Increasinglyprogrammabledevices

Incentive for misbehavior

Tools for misbehavior
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Impact of Selfish Misbehavior

• Benefits misbehaving users,at the cost of others
• Reduces trustworthiness of the network

Analogy Speeding on the highways
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Examples of Misbehavior

• Misbehavior can occur at all layers of the
  protocol stack

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ExamplePhysical Layer

• Using unnecessarily high transmit power

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ExampleMedium Access Control Layer

• 802.11 a wait-before-you-talk protocol
• By waiting less than recommended, misbehaving
  users benefit

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ExampleNetwork Layer

• In mesh networks,misbehaving users may use their
  links only when convenient to self

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Selfish Misbehavior

• Not unique to wireless networks
• TCP misbehaviors identified in the past
• But
• Wireless brings new challenges
• Misbehavior more likely in wireless networks due
  to limited resources

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Fundamental Challenges

• Wireless channel varies over space time
• Impossible to detect misbehavior with 100
  accuracy
• How to do well enough ?
• What are the limits on accuracy ?

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Fundamental Challenges

• Misbehavior cannot always be handled at the layer
  at which it occurs
• Cross-layer detection response

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Fundamental Challenges

• Different protocols must co-existon same slice
  of wireless spectrum
• Different protocolsdont necessarily know each
  other

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Research Agenda
A Civil Wireless Society

• Protocol mechanisms to Deter, Detect and
  Penalize misbehaviors, and Encourage Cooperation
• Layer-based classification of misbehaviors
• Determine fundamental limits

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Thanks!

• www.crhc.uiuc.edu/wireless