A Dynamic SWIPT Approach for Cooperative Cognitive Radio Networks.

Integrating simultaneous wireless information and power transfer (SWIPT) into cooperative cognitive radio networks (CCRN) can increase both energy and spectral efficiencies. In contrast to most of existing works that consider only relay transmission, this paper studies opportunistic relaying along with dynamic energy harvesting in SWIPT-based CCRN, where a secondary transmitter (ST) can act as relay for primary transmission and a secondary receiver (SR) has the energy harvesting function. We propose a new framework that can unify the direct transmission, relay transmission and energy harvesting. Under the proposed framework, we first assume the transmit power of the ST is fixed and formulate the optimization problem of maximizing the ergodic capacity for SR while meeting the ergodic capacity for the primary receiver and average harvested energy for SR, by joint transmission mode selection and transmit power splitting ratio selection. Then, for the case when the transmit power of the ST can be adjusted, we investigate the joint optimization of transmit power control, transmit power splitting ratio, and transmission mode selection. The two problems are nonconvex and we propose the optimal policies by using the dual Lagrangian method. Simulations validate the effectiveness of the proposed schemes. [ABSTRACT FROM AUTHOR]