Hybrid Analog-Digital Precoder Design for Securing Cognitive Millimeter Wave Networks

Millimeter wave (mmWave) communications and cognitive radio technologies constitute key of improving the spectral efficiency communications. Hence, we conceive a hybrid secure precoder for enhancing physical layer security mmWave wiretap channel, where secondary transmitter broadcasts confidential information signals to multiple users under interference temperature constraint primary user (PU). The optimization problem is formulated as jointly optimizing analog digital maximizing minimum secrecy rate all practical constraints. In particular, our design satisfies on maximum power received by PUs, well users’ quality-of-service (Qos), unit-modulus precoder. Due non-convexity resultant objective function owing coupling between precoder, nonconvex nonlinear, hence it very challenging solve directly. first transform into tractable form, develop penalty dual decomposition (PDD) based iterative algorithm locate its Karush-Kuhn-Tucker (KKT) solution. Finally, generalize proposed PDD relying finite-resolution phase shifters show that can be straightforwardly adapted handle scenario, each PU equipped with antennas CSI eavesdroppers (Eves) imperfectly known. Our simulation results validate algorithm.