Multi-User Hybrid Beamforming Design for Physical Layer Secured mmWave LOS Communications

Abstract

This paper proposes a hybrid beamforming design algorithm for a multi-user physical layer security modulation technique. The hybrid beamforming scheme is used in the base station to generate multi-beams according to the direction angle of the target users. The base station first uses a secure analog beamforming scheme to generate analog beams in multiple desired directions, then uses minimum mean square error (MMSE) to design the digital beamforming matrix to eliminate inter-beam interference. Due to randomly selecting a subset of antennas to transmit signals at the symbol rate, the base station transmits the defined constellation to the target users and projects the randomized constellation in the other angles. In addition, the superposition of signals is affected by a randomly selected antennas subset, resulting in higher sidelobe energy. However, due to the integer optimization target, the optimization problem of antenna subsets is non-trivial. Therefore, this paper proposes a cross-entropy iteration method to choose the optimal antenna combination to reduce the sidelobe energy. The simulation shows that the proposed method in this paper has about 10 dB lower sidelobe energy than the random selection method. Besides, the eavesdropper’s symbol error rate of QPSK is always 0.75, while the multi-target users meet the quality of service requirements.

Design of Low Probability Detection Signal with Application to Physical Layer Security

“…Another important line of research is the design of a practical system to achieve near-optimal physical layer security performance [17]. Zheng proposed a low-complexity polar-coded cooperative jamming scheme for the general two-way wire-tap channel, without any constraint on channel symmetry or degradation [18][19][20][21][22]. The research mentioned above is unexceptionally confined to the information-theoretic perspective, which only focuses on the LPI performance.…”