A Centralized Reputation System for MANETs Based on Observed Path Performance

A reputation system for MANETs is described that attempts to deduce nodal trustworthiness (forwarding behaviour) from observed end-to-end path performance. The trustworthiness deduction algorithm produces interval estimates and works well if node misbehaviour is not selective with respect to traversing paths. Nodal reputation levels are next calculated in the spirit of generous tit-for-tat so as to best reflect momentary nodal trustworthiness. High-reputed sources are favoured when forwarding transit packets (indirect reciprocity) and high-reputed paths are favoured by the multipath DSR. For a simplified network model and assuming the nodes are able to control their reputation levels with a view of a high source throughput, we find that high reputation may be costly to maintain. We examine an arising reputation game and conditions under which it produces a cooperation-stimulating Nash equilibrium.