The improper operation of the wireless devices due to the sudden depletion of batteries’ energy and also batteries replacing and/or recharging difficulties, have always been one of the important design considerations. Because of such reasons and due to the recent advances in wireless energy transfer (WET), the motivation for investigation on wireless power communication networks (WPCNs) has increased. In such types of networks, the energy of wireless devices can be permanently supplied through a hybrid-access point (H-AP) without human intervening. Furthermore, due to allocation of most of radio spectrum, the lack of available spectrum for future application such as WPCNs, is another challenging issue. A promising solution for this problem is combination of cognitive radio and WPCNs in the new form of cognitive wireless powered communication networks (CWPCNs). In general, data and energy transmission in the secondary network can be performed in Half-Duplex (HD) mode or Inband-Full Duplex (I-FD) mode depends on the type of the hardware of the equipment’s. In HD mode, all secondary users first harvest energy in a part of the frame that is called WET phase and then during the remaining part of the frame that is called WIT phase, transmit their information to the H-AP. This structure is called HD-CWPNC-HD. Recently, to improve spectral and temporal efficiency, the interests in researches about I-FD structures in which the devices can transmit and receive energy and data simultaneously (in the same frequency band) have increased. This structure is called FD-CWPNC-FD. Because of simultaneous energy transmission and data reception, self-interference cancellation (SIC) in the H-AP is one of design challenges in such a structure. In this thesis, the model of spectrum sharing is underlay. The goal is to maximize the sum-throughput of secondary users in both mentioned structures under different constraints such as interference temperature on primary receiver, the transmitted power of H-AP, the energy buffer capacity and also the comparison of such structures. It is shown that the STM problem is a convex optimization problem that can be solved using HETA and HJOTPA algorithms. In contrast with HETA in which equal length time slots are allocated to the secondary users, time slots are optimally allocated to SUs in HJOTPA. Numerical implementation in Mathab reveals that HJOTPA has better performance when compared with HETA. In addition, if SIC is performed appropriately, then FD-CWPCN-FD structure has higher sum-throughput than HD-CWPCN-HD one. keywords : Cognitive Wireless Powered Communication Network (CWPCN), Half-Duplex mode (HD), In-band Full Duplex mode (I-FD), Self-Interference Cancellation (SIC)