In this paper, two transmit antenna selection schemes are proposed for precoding-aided spatial modulation (PSM) to enhance the secrecy performance with reduced hardware complexity. The first strategy is determined by the channel state information (CSI) of both the legitimate and illegitimate links, called deterministic antenna selection based PSM (DAS-PSM), which selects partial transmit antennas to implement zero-forcing (ZF) precoding for maximizing the secrecy rate. For practical implementation, the low-complexity DAS-PSM criterion is demonstrated. The second strategy resorts to random antenna selection (RAS) with the aid of fast radio-frequency switching. Different from the DAS-PSM, this so-called RAS based PSM (RAS-PSM) dispenses with the CSI of the wiretap channel, which generates the ZF precoding matrix associated with randomly selected transmit antenna combination during each symbol period, creating additional turbulence that solely affects the eavesdropper. To combat the issue of low secrecy rate in the high signal-to-noise ratio regime due to the finite-alphabet inputs, time-varying artificial noise with extra power can be incorporated into both aforementioned strategies, which is exemplified in the RAS-PSM. Finally, the secrecy rates of both proposed schemes are theoretically analyzed and evaluated via Monte Carlo simulations, demonstrating that both proposed schemes with different requirements are capable of enhancing the secrecy performance compared to the conventional PSM.
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Manuscript received April 25, 2019; revised July 3, 2019; accepted July 7, 2019. Date of publication July 22, 2019; date of current version September 17, 2019. The work of Y. Huang, M. Wen, B. Zheng, and F. Ji was supported in part by the National Natural Science Foundation of China under Grant 61871190, in part by the Natural Science Foundation of Guangdong Province under Grant 2016A030308006 and Grant 2018B030306005, in part by the Pearl River Nova Program of Guangzhou under Grant 201806010171, and in part by China Postdoctoral Science Foundation under Grant 2018M640781 and Grant 2019T120731. The work of X. Cheng was supported by the National Natural Science Foundation of China under Grant 61571020 and Grant 61622101. This paper was presented in part at the IEEE Globecom Workshops, Singapore, December 4–8, 2017. The review of this paper was coordinated by Dr. C. Yuen. (Corresponding author: Miaowen Wen.) Y. Huang, M. Wen, B. Zheng, and F. Ji are with the School of Electronics and Information Engineering, South China University of Technology, Guangzhou 510641, China (e-mail: firstname.lastname@example.org; eemwwen@scut. edu.cn; email@example.com; firstname.lastname@example.org).
- Physical-layer security
- finite-alphabet inputs
- secret precoding
- spatial modulation
- transmit antenna selection