Impact of Battery Charging on Spectrum Sensing of CRN With Energy Harvesting.

This paper investigates the impact of battery charging on a cognitive radio network (CRN), where a hybrid overlay-underlay strategy enables mobile secondary nodes to access the licensed spectrum, and the secondary transmitter (ST) utilizes the energy harvested from the radio-frequency (RF) signal and the battery charging in the charging area for spectrum sensing and data transmission. We characterize the impact of battery charging in the charging area by designing an optimal spectrum sensing policy. The objective is to maximize the secondary throughput subject to energy and collision constraints. To be specific, a metric defined as a function of the spectrum sensor detection threshold is proposed to divide the CRN into three network states with respect to the relationship among energy consumption, energy harvesting, and battery charging. Accordingly, ST in the charging area decides to charge the battery or to exploit transmission opportunity. In each network state, we optimize the spectrum sensor detection threshold for the objective, which is a challenging problem since the spectrum sensor detection threshold is intertwined with the energy constraint, the collision constraint, and secondary throughput. Then we characterize the impact of battery charging in the charging area on the state classification and optimal spectrum sensing, respectively. Simulations show the effectiveness of the proposed metric, and validate the impact of battery charging. [ABSTRACT FROM AUTHOR]