Optimal spectrum sensing and transmission power allocation in energy-efficiency multichannel cognitive radio with energy harvesting

We consider an energy-efficiency multichannel cognitive radio (CR) where the secondary user (SU) can harvest the signal energy from the primary user (PU) to supply the power transmission. The goal of this paper is to determine an optimal joint spectrum sensing and transmission power allocation that maximizes the average throughput of the multichannel SU over all the subchannels subject to the constraints of subchannel sensing probabilities, interference power, and total transmission power. The SU harvests the PU energy, which is then converted into electrical energy and stored in the battery if the presence of the PU is detected, while consuming the stored energy to transmit data if the absence of the PU is detected. The allocation scheme is formulated as a joint optimization problem of spectrum sensing time and subchannel transmission power vector, whose optimal solution is obtained through the joint optimization algorithm based on alternating direction optimization. Analytical and numerical results show that the proposed energy-efficiency CR outperforms the traditional CR without energy harvesting, and the transmission power of the energy-efficiency CR improves both with the increasing of the spectrum sensing time and the presence probability of the PU.