Power efficient spectrum leasing in cooperative cognitive radios

Dynamic spectrum sharing plays a critical role in cognitive radio for the efficient spectrum utilization. In this paper, we consider a cooperative spectrum leasing model, in which the primary user (PU) may lease part of its bandwidth to the secondary user (SU) in exchange for the cooperation to maximize its power saving, under the constraint that its target is guaranteed. In return, the SU can take advantage of the leased bandwidth to transmit its own data. There is a tradeoff on how much bandwidth the PU should lease to the SU and how much power the SU should use for relaying the PU´s data. This problem can be formulated into a Stackelberg game, where the PU acting as the leader should determine the leased bandwidth to the SU and the SU acting as the follower should determine the relaying power. We analyze the condition when the PU and SU cooperate with each other and demonstrate the existence and uniqueness of the Stackelberg Equilibrium. Numerical and simulation results reveal that the proposed cooperative scheme can bring power saving of the PU up to 52% and bring a win-win situation for both the PU and the SU.