Second-Ordered Reputation and Incentive Mechanism in Ad Hoc Networks

The incentive mechanisms based on reputation are often used to induce cooperation among selfish nodes to route and forward packets in ad hoc networks. Those mechanisms propose that nodes with lower reputation value will receive less benefit. This class of schemes suffers from a new problem of second-ordered free riding. Refusing service request from nodes with low reputation will increase the defector's own reputation, so refusing isn't always a favorable choice for selfish node. Modifying the basic scheme to mitigate this new selfish behavior is important to improve the cooperation in ad hoc networks and enhance system robustness. The paper discusses the second-ordered free-riding problem in incentive mechanism for packet forwarding in ad hoc networks and proposes a new scheme based on second-ordered reputation combining with a probabilistic service assignment rule. It is proved that the new scheme is available and cooperation can be built in various network settings. An evolutionary game model is introduced and the discrimination strategy may dominate the whole network gradually. It is also robust in the case there are various errors.