PIM: A Policy-Based Incentive Mechanism for Promoting Honest Recommendations in Reputation Systems

The efficiency of the reputation mechanism fully depends on the number of received recommendations and the quality of each of them, but a peer may not be willing to provide honest recommendations actively in order to maximize his revenues. Therefore, this paper presents a Policy-based Incentive Mechanism (PIM) implemented through a fair differential service mechanism. To achieve this goal, first, we define two parameters that can be used to create service differentiation in reputation information exchange, namely, level of participation and recommendation credibility. These two parameters identify the peer´s behavior characteristics in reputation system. We take the interest of peers into account when computing the levels of their participation so as not to falsely classify these active peers of lacking experiences as inactive ones. Second, based on the above two parameters, we propose a simple but effective reputation information exchange protocol to elicit sufficient and honest participation. Theoretical analyses and simulations show that, the incentive mechanism can stimulate rational peers to send honest recommendations actively and lay a foundation for getting an accurate reputation evaluation.