Physical Layer Security in Millimeter-Wave Communication

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He, Miao
Physical layer security , mmWave , Array antenna , Wireless communication
Due to operating at high carrier frequencies (30-300 GHz), the millimeter-wave (mmWave) communication has many advantages. To preserve the secrecy for the mmWave wireless communication, in addition to the data encryption with cryptographic keys, physical layer security (PLS) is another effective technique to achieve secret communication. The inherent randomness of wireless channels are exploited to ensure the confidential information carried by the signals can only be obtained by the target users, but not by the unauthorized users. The implementation of the PLS mmWave communication systems should consider the characteristics of the mmWave channels, as well as some requirements (computational complexity, hardware cost and multicast demand) and practical limitations (imperfect hardware) in engineering. First, we consider to reduce the computational complexities in the PLS mmWave communication systems. The high computational complexities are the barriers for practical implementations. Second, we consider the demand on multicast transmission in practical implementations. Currently, a few PLS schemes support secret multicast transmissions by solving the optimization problems with the conditions of abundant computational resources and known eavesdroppers' channel state information. Such conditions may not be met in practical implementations. In addition, we consider the phase quantization errors of the phase shifters in the phased-array antennas. The phase quantization errors have adverse effects on the PLS mmWave communication performances. Lastly, we consider to reduce the hardware costs and simplify the structure complexities of the PLS mmWave communication systems in practical implementations. In order to reduce the heavy computational burdens, a light-weight algorithm for the phased-array PLS mmWave communication system is proposed. For the multicast transmission, we propose a scheme based on an integrated oblique projection approach. The proposed scheme achieves multicast PLS mmWave communication without the knowledge of eavesdroppers' channel state information, at low computational complexities. Based on the analyses on the transmission gain with phase shifter quantization errors, we develop a compensation scheme to address the phase deviation caused by phase quantization errors. To reduce the hardware costs, we propose a scheme with an analog dual-shifter-structure, which achieves multicast PLS mmWave communication at affordable hardware costs.
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