Simultaneous spectrum sensing and energy harvest in cognitive radio

In order to save the electric power of cognitive radio (CR), a novel notion that simultaneous spectrum sensing and energy harvest is proposed, which uses the harvested RF energy of the PU signal to supply the electric power of spectrum sensing. The time switching model and power splitting model are developed to realize the notion. In the time switching model, the SU performs either spectrum sensing or energy harvest at any time, while in the power splitting model, the received PU signal is split into two signal streams, one for spectrum sensing and the other one for energy harvest. A joint optimization problem of sensing time and time (or power) division factor is proposed to maximize the spectrum access probability of the SU. The simulation results have shown that there deed exists an optimal sensing time that maximizes the spectrum access probability, providing that the harvested energy is enough to supply the spectrum sensing.