On Residual Energy Maximization in Energy Harvesting Cognitive Radio Network

Recent advancement in wireless communications demands high data rate transmission at low power consumption. To this aim, the present work proposes an energy harvesting based cognitive radio (CR) system operating in time slotted mode. Energy harvesting and spectrum sensing (SS) are done simultaneously by the CR user through power splitting mode. On the other hand, during the transmission time slot, the CR user either harvests energy or transmits its own data based on SS decision result. An optimization problem is developed to maximize the residual energy under the constraints of sensing reliability of the PU and spectrum efficiency (SE) target rate of the CR. The concavity of the objective function is shown which ensures a global solution to the problem. Closed form expressions for the sensing time and CR transmit power are found and the results are validated by simulations.