Secrecy Rate Maximization in Multi-IRS Millimeter Wave Networks
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In this paper, the problem of physical layer security enhancement in a millimeter-wave (mmWave) network equipped with multiple Intelligent Reflecting Surfaces (IRSs) is investigated. In this network, the IRSs assist in signal transmission from the Base Station (BS) to desired users and at the same time in securing signals from an unauthorized eavesdropper. Our objective is to maximize the secrecy rate by jointly optimizing the active and passive beamformers at the base station and IRSs, respectively. The optimization problem is non-convex and hence, we solve it by decomposing it into two disjoint active and passive beamforming design sub-problems and then iteratively solving them by alternating and Semi-Definite Relaxation (SDR) techniques. Simulation results show the advantage of using multiple IRSs in secrecy rate enhancement of the mmWave networks. In additio12n, we show how the secrecy rate improves with the number of IRSs in the network and also with the number of reflecting elements at the IRS.
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