A Spectrum and Energy Cooperation Strategy in Hierarchical Cognitive Radio Cellular Networks

In this letter, we proposed a novel spectrum and energy cooperation strategy in a hierarchical cognitive radio (HCR) cellular network. In our design, the primary receiver (PR) is equipped with a time-splitting energy harvesting (EH) device such that the primary system (PS) can share its spectrum to the secondary system (SS) and harvest the radiation for charging from the secondary base station (SB) in return. To achieve such a win-win strategy, the SB's precoder and the time-splitting factor are jointly optimized by maximizing the SS's information rate, providing that the PS's information rate and harvested energy are guaranteed. The design problem is equivalently formulated and solved via a semidefinite relaxation (SDR) optimization approach. Simulation results show the promising performance of the proposed cooperation strategy.