Dynamic power allocation for spectrum sharing in interference alignment (IA)-based cognitive radio

In cognitive radio networks (CRN), underlay spectrum sharing allows secondary users (SUs) to utilize the spectrum on which the primary users (PUs) are working at the same time, without introducing intolerant interference. Interference alignment (IA) is a prospective technique for interference management, and can significantly improve the performance of cognitive radio (CR) networks. Besides, power allocation (PA) in IA-based CR networks is greatly neglected, which can further reinforce its performance. Thus in our paper, PA in IA-based CR networks is analyzed. To satisfy the QoS requirement of the PU, its minimal transmitted power is derived. To maximize the total rate of CRN and maintain the fairness between the competing SUs, the system is modeled as an optimization problem with the constraints of transmission power in IA-based cognitive radio. Based on this study, we propose the optimal transmission power allocation algorithm. Extensive simulation results show that the proposed optimal algorithm can improve the system capacity and maintain the fairness compared to the existing algorithms.