Wireless information and power transfer in an underlay cognitive radio network

In this paper, we consider a secondary network with simultaneous wireless information and power transfer in a spectrum sharing scenario. In particular, a secondary user (SU) transmitter communicates with multiple SU receivers (SU-Rxs) under the peak interference power constraint of the primary user receiver and the SU maximum transmit power limit. We apply a channel quality-based threshold and exploit opportunistic scheduling. Specifically, an SU-Rx with best channel condition among a set of SU-Rxs satisfying the threshold is scheduled for data transmission. The remaining SU-Rxs with channel condition below the threshold, harvest the radio frequency energy. Analytical expressions of the SU ergodic capacity, symbol error rate, throughput, and energy harvesting are obtained. An optimal threshold satisfying a given target outage probability is determined. Numerical results are provided to investigate the impact of different parameters on the secondary network performance.