Performance Evaluation of Trust-Based Collaborative Sanctioning in MANETs

Collaborative sanctioning (CS) is necessary in mobile ad hoc networks (MANETs), as cooperation in packet forwarding of network members is crucial. CS provides incentives for good behaviour, hence, it induces nodes with self regarding preferences to act cooperatively. CS requires nodes to use mechanisms that will evaluate how cooperative are peers requesting forwarding service. In this article we investigate the conditions where the most simple and reliable mechanism based on a trust system is sufficient for CS, from the conditions where it needs to be extended with a reputation system. Using a simple model of MANETs we demonstrate that the basic approach -- a trust system that uses personal evidence -- if applied by the majority of nodes -- results in poor network performance. However, if general evidence is used in addition to the personal one, the performance of the network is relatively good as long as the number of non-cooperative nodes is low. We show that extension of a trust system with a reputation system always improves performance of the network. Nevertheless, the need for a reputation system is strongest when the majority of nodes uses personal evidence.