Outage probability in cognitive wireless powered communication networks considering QoS in primary networks

In this research, we investigate the outage probability of the secondary network in a cognitive wireless powered communication network (WPCN). Energy-constrained secondary users harvests energy from a hybrid access-point and a primary transmitter in the first phase. In the second phase, the secondary user with the best uplink channel is selected. In this setup, the secondary network can share the spectrum with the primary network ensuring that a desired outage probability constraint in the primary network is always met. This constraint represents the quality-of-service (QoS) of the primary network. The analytical expressions of the outage probability of the secondary network are provided and verified by numerical simulation. We demonstrate that relaxing the QoS of the primary network can considerably improve system performance. We show that the transmit power of the selected secondary user and harvesting energy time have a significant impact on the outage probability of the secondary network.