FACT: Facilitating Trustworthy Services in Mobile IoT Systems

Mobile Internet of Things (IoT) users possess dynamic service requirements in a real IoT system and always try to get services from trusted entities, which we term as facility nodes. However, the trustworthiness of the facility nodes varies from location to location, depending upon the service quality and user feedback. Therefore, a service provider may have different trust scores for its deployed facility nodes in different locations. It is always crucial for an IoT user to ensure that service has been taken from trustworthy nodes. In this article, we consider an IoT service provisioning architecture, where an IoT user requests services from nearby trusted nodes that are deployed by service providers other than the user's own registered service provider. To serve the requests from these unregistered users, the facility nodes incur additional costs. Furthermore, due to heterogeneous service requirements, IoT users prefer composite microservices from a set of facility nodes. In such cases, it is difficult to design a pricing scheme to incentivize the facility nodes. Therefore, we propose a pricing mechanism based on a two-stage Stackelberg game and analyze the interactions between the IoT users and the facility nodes, while considering the trust scores and service charges. In the game model, the facility nodes act as the leaders, and the IoT users act as the followers. Using backward induction, we analyze the existence and uniqueness of the Stackelberg equilibrium. Finally, the numerical results based on the mobility traces of a real map show that the proposed scheme incentivizes both the IoT users and the facility nodes, while ensuring trusted services.