Two-level bargain game for spectrum leasing in cognitive radio networks

In cognitive radio networks, when the primary user (PU) who has a minimum transmission rate requirement is experiencing a bad channel condition, it can resort to the cooperation with the secondary users (SUs) in exchange for a fraction of its licensed spectrum. However, due to the selfish nature, the SUs may not act as cooperatively as to meet the PU´s Quality of Service (QoS) requirement. On the other hand, the SUs may not exploit efficiently the benefit from cooperation if they compete with each other and collaborate with the PU independently. Therefore, how to stimulate the SUs to form a group to cooperate with the PU while guarantee the PU´s QoS requirement are critical challenges. In this paper, we propose a two-level bargain framework to address the aforementioned problems. In the proposed framework, the interaction between the PU and the SUs are modeled as the first level bargain game while the second level bargain game is used to formulate the SUs´ decision making process on spectrum sharing. We analyze the optimal actions of the PU and the SU and derive the theoretic results for the one-PU one-SU scenario. To find the solutions for the one-PU multi-SU scenario, we propose a revised numerical searching algorithm and prove its convergence. Finally, we demonstrate the effectiveness and efficiency of the proposed scheme through simulations.