In this paper, we propose a new multi-antennas hierarchical cognitive radio, in which a primary system (PS) not only shares the spectrum resources with a secondary system (SS), but also harvests energy from the SS, achieving a new simultaneous wireless information and power transfer paradigm. Specifically, the secondary transmitter (ST) can help relay PS's signals via an amplify-and-forward protocol, and a power splitting energy harvesting device is additionally adopted at the primary receiver

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... PR). A cooperative strategy is proposed for maximizing the achievable rate of the SS while ensuring PS's achievable rate and PR's harvested energy, by jointly optimizing a precoder at the primary transmitter, two precoders at the ST (for the PS and SS, respectively), an equalizer at the secondary receiver, and a power splitting factor for the PR. Since the optimization problem is complicated and non-convex, we propose an alternating optimization approach to decompose the original problem into three subproblems, which can finally be formulated as semi-definite programming, difference of convex, and generalized eigenvalue problems. The closed-form solutions are, then, tractably derived. The numerical results are carried out to demonstrate the effectiveness of the proposed design. INDEX TERMS Hierarchical cognitve radio network (HCR), simultaneous wireless information and power transfer (SWIPT), amplify-and-forward (AF), energy harvesting (EH), semidefinite relaxation (SDR), difference of convex (DC).