Robust Max-Min Fairness Energy Harvesting in Secure MISO Cognitive Radio With SWIPT

A multiple-input single-output cognitive radio downlink network is studied with simultaneous wireless information and power transfer. In this network, a secondary user coexists with multiple primary users and multiple energy harvesting receivers. In order to guarantee secure communication and energy harvesting, the problem of robust secure artificial noiseaided beamforming and power splitting design is investigated under imperfect channel state information. Specifically, the maxmin fairness energy harvesting problem is formulated under the bounded channel state information error model. A onedimensional search algorithm based on S-Procedure is proposed to solve the problem. It is shown that the optimal robust secure beamforming can be achieved. A tradeoff is elucidated between the secrecy rate of the secondary user receiver and the energy harvested by the energy harvesting receivers under a max-min fairness criterion.