Cognitive wireless powered communication networks with secondary user selection and primary QoS constraint

In this research, the authors investigate the outage probability (OP) of the secondary network in a cognitive wireless powered communication network. Energy-constrained secondary users harvest energy from a hybrid access-point (H-AP) and the primary transmitter in the first phase. In the second phase, they select a secondary user based on two different schemes, namely the best uplink channel selection (UCS) and the minimal interference channel selection (MICS), to transfer information to the H-AP. The secondary network can share the same spectrum with the primary network ensuring that a desired OP constraint in the primary network is always met. This constraint represents the quality-of-service (QoS) of the primary network. The analytical expressions and asymptotic expressions of the OP of the secondary network are derived. The result shows that increasing the number of secondary users can considerably improve system performance. The transmit power of the selected secondary user, energy harvesting time and relaxing the QoS constraint of the primary network have a significant impact on the OP of the secondary network. The results show that UCS outperforms MICS.