Incentive Mechanism Based Cooperative Spectrum Sharing for OFDM Cognitive IoT Network

Internet of Things (IoT) is considered as the future network to support machine-to-machine communications. To realize IoT network, a large number of IoT devices need to be deployed, which will lead a problem of allocating sufficient spectrum for the rapidly increasing devices. Through cooperative spectrum sharing, the unlicensed IoT devises (UIDs) help forward the signal of primary users (PUs) to exchange for dedicated spectrum to transmit their signals, which can effectively improve the spectrum utilization for the IoT network. However, UIDs are selfish and rational. They may not be willing to take participate in the cooperative spectrum sharing after considering the potential costs. It is necessary to provide effective incentives to encourage them to take part in the cooperative spectrum sharing. In this paper, we use contract theory to model the incentive mechanism in OFDM-based cognitive IoT network under a practical scenario with incomplete information, where UIDs’ private information (i.e., transmission cost and wireless channel characteristics) are not known by PUs. By using contract theory, the negotiations between PUs and UIDs are modeled as a labor market, where PUs and UIDs act as the employer and employees, respectively. We first study the optimal contract design to maximize PUs’ utility as well as the social welfare, in which the contract consists of a menu of expected signal-to-ratios and payments over each subcarrier. Then, we propose heuristic UIDs’ selection method with a finite PUs’ budget. Finally, simulation results demonstrate the efficiency of our proposed contract design and UIDs selection method.