IMac: Strategy-proof incentive mechanism for mobile crowdsourcing

Mobile crowdsourcing with smartphones advocates the cooperative effort of mobile smartphones to perform a joint distributed sensing task, which has gained growing importance for its potential to support a wide spectrum of large-scale sensing applications. Smartphone users in the real world are strategic and rational. Thus, one crucial problem in mobile crowdsourcing with smartphones is to stimulate cooperation from smartphone users. Several major challenges should be addressed. First, the actual cost incurred for a sensing task is private information and unknown to other users and the mobile crowdsourcing platform. Second, smartphone users are strategic, which suggest a user may deliberately misreport its cost (different from the real cost) in order to maximize its own utility. In this paper, we propose a strategy-proof incentive mechanism called iMac based on the Vickrey-Clarke-Groves (VCG) mechanism. The main idea of iMac is to stimulate smartphone users to truthfully disclose their real costs in spite of strategic behavior of the users. iMac introduces two main components. The first component determines the allocation of a sensing task to smartphone users given the user costs. And the second component decides the payment to each user. We prove that iMac can successfully produce a unique Nash equilibrium at which each user truthfully discloses the cost. Meanwhile, the minimization of the social cost is achieved. Simulation results demonstrate iMac achieves the desired design objectives and the overpayment is modest.