A three-dimensional continuous-time Markov model is proposed for an energy harvesting cognitive radio system, where each secondary user (SU) harvests energy from the ambient environment and attempts to transmit data packets on spectrum holes in an infinite queuing buffer. Unlike most previous works, the SU can perform spectrum sensing, data transmission, and energy harvesting simultaneously. We determine active probability of the SU transmitter, where the average energy consumption for both spectrum sensing and data transmission should not exceed the amount of harvested energy. Then, we formulate achievable throughput of secondary network as a convex optimization problem under average transmit and interference energy constraints. The optimal pair of controlled energy harvesting rate and data packet rate is derived for proposed model. Results indicate that no trade-off is available among harvesting, sensing/receiving, and transmitting. The SU capability for self-interference cancelation affects the maximum throughput. We develop this work under hybrid channels including overlay and underlay cases and propose a hybrid solution to achieve the maximum throughput. Simulation results verify that our proposed strategy outperforms the efficiency of the secondary network compared to the previous works. KEYWORDS throughput, optimization, energy harvesting, spectrum sensing, Markov model, self-interference cancelation 1 | INTRODUCTIONDuring recent years, energy harvesting cognitive radio has been emerged as a novel technology to exploit unused spectrum band and energy from the surrounding environment. Opportunistic spectrum access is a practical architecture for discovering spectrum holes and supports the primary user (PU) from harmful interference in a cognitive radio. In many cognitive radio scenarios, the SUs have a battery-power source for sensing spectrum and transmitting data. Energy harvesting offers a useful solution, which allows the SUs to harvest energy from the environmental energy sources such as surrounding radio power, mechanical vibrations, solar, and other natural phenomena.During the last decade, energy crisis has attracted a lot of attention. Renewable energy sources can reduce the prices and the demand for conventional energy supplies. In addition, efficient use of energy is regarded as an important issue for wireless communication services. In order to solve such problems, a lot of works such as energy-efficient protocol design and energy-saving hardware have been implemented. 1,2 Energy harvesting has been considered as promising technology which can store unlimited energy unlike battery-power systems. Furthermore, spectrum scarcity is another prominent problem in wireless communication networks. Dynamic spectrum access technique can improve the network efficiency and simplify the spectrum reuse. It allows the SUs to access the white spaces when the licensed spectrum band is not occupied by the PUs and share the spectrum until the PUs are appropriately protected. 3,4 A large body of research has been c...