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Universität Karlsruhe GERMANY. Stimulating Cooperative Behavior of Autonomous Devices An Analysis of Requirements and Existing Approaches. The Second International Workshop on Wireless Information Systems 22. - 23. April 2003 – Angers, France.
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Universität Karlsruhe GERMANY Stimulating Cooperative Behavior of Autonomous Devices An Analysis of Requirements and Existing Approaches The Second International Workshop on Wireless Information Systems 22. - 23. April 2003 – Angers, France Philipp Obreiter, Birgitta König-Ries, Michael Klein Universität Karlsruhe Institute for Program Structures und Data Organization DIANE Project http://www.ipd.uni-karlsruhe.de/DIANE
Autonomy • Autonomous devices • devices are free to cooperate or not • Sound assumption • tampered devices • re-engineered protocol stacks • absence of an enforcing authority • Devices tend to be uncooperative • scarceness of resources (e.g. battery power) cooperative behavior must be stimulated
Overview • Cooperation and uncooperative behavior • Issues for Incentive Schemes • Existing Incentive Schemes
User Interface User Interface Application Application Discovery Discovery Transport Transport Network Network Link Link autonomy border Conceptual Layering device A device B
action Agent Principal remuneration Application Layer Network Layer service forwarding Provider Consumer Router Sender check reputation Elementary Cooperation
uncooperative behavior unreasonable reasonable misbehavior venial noncooperation profitable unprofitable profitable misbehavior malicious behavior by agent by principal selfish behavior lavish behavior Taxonomy of Uncooperative Behavior
Discovery Discovery Transport Transport Network Network Application Application Exemplification of Uncooperative Behavior Drop other devices' advertisements selfish behavior Wastefully consume other devices' services lavish behavior User Interface User Interface Application Application Discovery Discovery Transport Transport Dropping packets under heavy load venial noncooperation Network Network Link Link DoS attack malicious behavior
Incentive Schemes • Incentive Scheme • set of mechanisms that • restrict misbehavior • exempt venial noncooperation from punishment • Current approaches for Ad Hoc Networks • TermiNodes • Sprite • APE • RPG • Watchdog/Pathrater • CONFIDANT • CORE
Issues for Incentive Schemes • Trust • Transactions • Remuneration types
Incentive Scheme Issues: (1) Trust • Trust • prerequisite for remuneration mechanisms • an incentive for cooperation • Static Trust • certification of an entity's trustworthiness • requires cryptographic infrastructure • Dynamic Trust • arises from prior experiences • need for reputation management • considers behavioral change
Incentive Scheme Issues: (2) Transactions • Transaction • encompasses elementary cooperation • agent executes action iff principal remunerates agent • Negotiation phase • agreement on the action and remuneration • determined by the respective cost/profit ratios • Processing phase • assertion of atomicity seems daunting • approximated atomicity • by interleaving action and remuneration • efficient low value transactions • by aggregating actions and remunerations
Incentive Scheme Issues: (3) Remuneration • Remuneration type • different types have been proposed • most popular types • checks, e.g., TermiNodes • reputation, e.g., Marti et al 2000 • Transferability • passing on checks • disseminating reputation • Convertibility • cashing checks • reconciling user and device views of reputation
Account Based Incentive Schemes: Properties • Remuneration mechanism • every entity possesses an account • accounts stored on virtual banks • principal issues a check • agent accesses a virtual bank in order to credit its account • Implementation • requires static trust mechanisms • virtual banks managed by dedicated devices • banker nodes • accessibility? • accounts distributed to account holders • tamper resistant hardware
Reputation Based Incentive Schemes: Properties • Remuneration mechanism • principal adapts agent's reputation according to its action • agent might decrease principal's reputation • agent only cooperative if principal has good reputation • Implementation • couple trust and remuneration • local views of reputation may be • kept local • shared, i.e., disseminated • increases effectiveness • introduces further opportunities for misbehavior • requires stable or localized cooperation patterns
Conclusion • Summary • cooperation beyond autonomy borders requires stimulation • cooperation of protocol entities on different layers • taxonomy and exemplification of uncooperative behavior • discussion of incentive schemes • trust • transactions • remuneration • classification of existing approaches for ad hoc networks • account vs. reputation based • Future work • incentive scheme for the discovery and application layer • analysis of suitable remuneration types • integration of incentive schemes
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