Power trading in cognitive radio networks

Cognitive radio technology has been proposed to improve spectrum utilization by sharing the frequency spectrum bands between licensed and unlicensed users, called primary users (PUs) and secondary users (SUs), respectively. The main objective of the SUs is to achieve their quality of service (QoS) by exploiting the unused parts of the spectrum, while the PUs aim to reap extraordinary profits by leasing their unused portions of the spectrum. Pricing and transmission power are two key issues of interest to both PUs and SUs. Game theory has been considered as a useful tool for discussing the power control issue in wireless networks. In this paper, we consider the issue of power trading and propose two different models. First, a power-pricing model without game theory is developed, wherein the PUs obtain some revenue by renting their unused frequencies to SUs that use suitable power levels to transmit. The suitable power level ensures that the use of the spectrum by SUs does not interfere with other users in the network. Second, a non-cooperative game is applied to the proposed pricing model among the system users (i.e., PUs and SUs), to create balance between them. This balance point is known as the "Nash equilibrium." Performance evaluations of the proposed models are provided, demonstrating their efficiency and how they help in using the frequency spectrum more efficiently. The developed models allow the PUs to increase their gained profit while the SUs can use the spectrum for their data transmissions.