Sum-Throughput Maximization of Secondary Users in an In-Band Full-Duplex Cognitive Wireless Powered Communication Network

Abstract

This paper studies a cognitive wireless powered communication network (CWPCN). Such a network consists of some distributed secondary users (SUs) and a hybrid access point (H-AP) as a secondary network which is in the vicinity of a primary network. In this model, H-AP and SUs can operate in two modes which are an in-band full-duplex (I-FD) mode and the half-duplex (HD) mode. In the former mode, the network is called FD-CWPCN-FD while for the latter mode the HD-CWPCN-HD is used. An underlay spectrum sharing model is also considered. The goal is to maximize the sum-throughput of SUs by optimal selection of allocated time and energy to SUs in both I-FD and HD modes. By using convex optimization techniques and proposing an algorithm that is called H-AP-based joint optimal time and power allocation, we obtain the closed-form expressions for the optimal allocated time and energy. Numerical results illustrate when the transmitted power from H-AP is low or self-interference cancellation in H-AP is more accurate, FD-CWPCN-FD has higher sum-throughput than HD-CWPCN-HD.