Energy Harvesting In Cellular Underlay Cognitive Networks: Rate-Energy Trade-off Characterization

In classical communications, information massage has been considered as the only entity to be transferred between communicating pairs. However, recently by the feasibility of energy harvesting at the hand-held devices, the power transmission is of great importance as well. Thus, the users demand for both information rate and radio frequency (RF) signal energy. Due to the natural trade-off between rate and energy demands, we study the optimal transmission in underlay cognitive cellular networks, where the primary users demand information and energy at a particular time instant. On one hand, in order to satisfy the energy demands of the primary users, the transmitters of the secondary users are activated which deteriorates the achievable rates of the primary users on the other hand. The rate region of the primary users is studied while utilizing power splitting at the receivers for joint information detection and energy harvesting purposes. In order to deliver the outer-most boundary of the rate region, we formulate the weighted max-min optimization problem well-known as weighted Chebyshev problem. Numerically, we show the influence of energy harvesting constraint on the rate region of primary users.