Cooperative Precoding for Wireless Energy Transfer and Secure Cognitive Radio Coexistence Systems

This letter studies the cooperative precoding design for a coexisting wireless energy transfer (WET) and cognitive radio (CR) system, where the WET system share the same spectrum with the CR system. Different from the traditional wireless networks, interference here is regarded as a useful rather than harmful resource. Specifically, we address the transmit covariance design to minimize the total transmit power at the energy transmitter and the secondary transmitter while satisfying secrecy rate, energy harvesting, and interference temperature constraints. We propose an iterative algorithm to tackle the formulated nonconvex optimization problem, and prove that it could converge to a Karush-Kuhn-Tucker point of the original problem. Simulation results are finally provided to illustrate the effectiveness of our proposed algorithm.