Adverse selection based incentive mechanism for cooperative caching in distributed storage system

Cooperative caching that utilizes the distributed storage of popular files is regarded as one prospective technology for offloading the traffic for the base station (BS) and boosting the capacity of the wireless networks. It's a critical issue to achieve the goals that the content providers (CPs) are encouraged to download and cache the popular content items so that the CPs can share them with the content requesters (CRs). In this paper, we consider the BS as an employer and the CPs as the employees according to the framework of contract theory. Different from most of the existing incentive mechanisms which solve the adverse selection problem, we classify the CPs into multiple types according to two-dimensional factors: the storage space and connectivity, both of which are private information of the CPs. Next, the BS, aiming to maximize its utility, designs the proper contracts for all types of CPs to motivate them to help traffic offloading. Moreover, the storage placement of popular content items is proposed according to optimal matching. Finally, the numerical results demonstrate the feasibility of the proposed incentive mechanism and the superiority of considering two-dimensional factors.