Abstract: In order to improve the performance of overlay cognitive radio-wireless powered communication networks(CR-WPCNs), ambient backscatter communication technology is introduced to improve the throughput of secondary system. In CR-WPCNs based on ambient backscatter communication, considering the limited transmission distance of secondary transmitters, a relay transmission scheme based on non-orthogonal multiple access and energy harvesting is proposed, which improves the communication range and the throughput of secondary system. When the channel is busy, secondary transmitters will perform the ambient backscatter communication as well as the energy harvesting, and relays will perform the energy harvesting. The time resource allocation of this period needs to be taken into account. When the channel is idle, both secondary transmitters and relays will utilize the harvested energy to perform the active radio transmission, respectively. The time resource allocation of this period also needs to be taken into account. Based on these resource allocation problems, a throughput maximization problem for secondary system is formulated, and the Lagrange multiplier iterative algorithm is utilized to solve this problem. Simulation results demonstrate that the proposed scheme can significantly improve the throughput of secondary system.

Key words: cognitive radio, ambient backscatter communication, relay transmission