Abstract
Multi-hop ad-hoc networks, aka MANETs, are composed of a set of communicating mobile devices. Users of such devices are usually selfish and try to save their resources (e.g. battery life). Therefore providing services to other users is considered as costly. However at the same time there is a need to cooperate with other devices in order to achieve high level services like messaging throughout the network. We propose a game-theoretical model based on the notion of prisoner dilemma and trust in order to enable cooperation and enhance service level in such networks. Local strategies of players are optimized using a genetic algorithm. In the random-pairing prisoner dilemma, it is assumed that for each interaction, the opponent is randomly chosen. While in our model, we suppose that there will be a limited number of iterations between the opponents. This gives them the opportunity to fine-tune their strategy based on short-term memory and trust relationship. By providing a service to another user they indeed gain trust and hope that one day there will be a return, i.e. that this other user will help them back. First results indicate that it is sufficient to have very limited sets of repeated interactions in order to gain trust and cooperation. We then extend the approach to the case where authentication is provided (e.g. based on some unique IDs) and apply it the source routing. Routes are then chosen not only based on the shortest path but also on the reliability/reputation of these paths. A reputation of a path relies on the trust level that the emitter gives to intermediary nodes.
