Spectrum leasing and relay selection for cooperative cognitive radio network using potential game

In cognitive radio networks, cooperation between users can improve each network´s performance. In this paper, a cognitive relay network is considered where the secondary users (users in Ad-Hoc network) are involved as cooperative relays in primary users´ communication. The primary user owns a given bandwidth and can decide to lease it for a fraction of time to secondary users in exchange for appropriate remuneration. A group of secondary users in Ad-Hoc network are selected using potential game to maximize the primary user´s transmission, so that primary user´s buffer will be depleted faster, resulting in more channel idle time, namely more transmission opportunities for secondary users. We consider a baseline scenario with full channel state information and information theoretic transmission strategies. Feasibility and existence of the Nash equilibrium (NE) in potential game are proved, and an iterative algorithm of relay selection is designed. Moreover, the impact of different system parameters on primary user selection for secondary Ad-Hoc network is analyzed. Simulation results show that the primary user and secondary Ad-Hoc network can achieve higher utilities by spectrum leasing based on trading secondary spectrum access for cooperation.