1. Selfish Misbehavior in Wireless Networks
Nitin Vaidya
University of Illinois at Urbana-Champaign

2. Increasing Wireless Deployment in Unlicensed Bands
Hot-spots
Community wireless networks
Home networks
Sensors …

3. Users Must Trust the Network
“Wired-equivalent” privacy mechanisms
Going beyond privacy …
Users must be able to rely on
“ fair ” competition

4. } } Unlicensed Bands The New Wild Wild West ? Increasing demand
Limited resources
Few rules !
Increasingly programmable devices }
Incentive for
misbehavior }
Tools for
misbehavior

5. Impact of Selfish Misbehavior
Benefits misbehaving users, at the cost of others
Reduces trustworthiness of the network
Analogy : Speeding on the highways

6. Examples of Misbehavior
Misbehavior can occur at all layers of the protocol stack

7. Example: Physical Layer
Using unnecessarily high transmit power

8. Example: Medium Access Control Layer
a wait-before-you-talk protocol
By waiting less than recommended, misbehaving users benefit

9. Example: Network Layer
In mesh networks, misbehaving users may use their links only when convenient to self

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

11. 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 ?

12. Fundamental Challenges
Misbehavior cannot always be handled at the layer at which it occurs
Cross-layer detection & response

13. Fundamental Challenges
Different protocols must co-exist on same slice of wireless spectrum
Different protocols don’t necessarily know each other

14. 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

15. Thanks!