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Physical Layer Security over Fluid Antenna Systems: Secrecy Performance Analysis

Farshad Rostami Ghadi, Kai-Kit Wong, F. Javier Lopez-Martinez, Wee Kiat New, Hao Xu, Chan-Byoung Chae

TL;DR

Numerical results indicate that applying the fluid antenna with only one activated port to PLS can guarantee more secure and reliable transmission, when compared to traditional antenna systems (TAS) exploiting maximal ratio combining (MRC) and antenna selection (AS) under selection combining (SC).

Abstract

This paper investigates the performance of physical layer security (PLS) in fluid antenna-aided communication systems under arbitrary correlated fading channels. In particular, it is considered that a single fixed-antenna transmitter aims to send confidential information to a legitimate receiver equipped with a planar fluid antenna system (FAS), while an eavesdropper, also taking advantage of a planar FAS, attempts to decode the desired message. For this scenario, we first present analytical expressions of the equivalent channel distributions at the legitimate user and eavesdropper by using copula, so that the obtained analytical results are valid for any arbitrarily correlated fading distributions. Then, with the help of Gauss-Laguerre quadrature, we derive compact analytical expressions for the average secrecy capacity (ASC), the secrecy outage probability (SOP), and the secrecy energy efficiency (SEE) for the FAS wiretap channel. Moreover, for exemplary purposes, we also obtain the compact expression of ASC, SOP, and SEE by utilizing the Gaussian copula under correlated Rayleigh fading channels as a special case. Eventually, numerical results indicate that applying the fluid antenna with only one activated port to PLS can guarantee more secure and reliable transmission, when compared to traditional antenna systems (TAS) exploiting maximal ratio combining (MRC) and antenna selection (AS) under selection combining (SC).

Physical Layer Security over Fluid Antenna Systems: Secrecy Performance Analysis

TL;DR

Numerical results indicate that applying the fluid antenna with only one activated port to PLS can guarantee more secure and reliable transmission, when compared to traditional antenna systems (TAS) exploiting maximal ratio combining (MRC) and antenna selection (AS) under selection combining (SC).

Abstract

This paper investigates the performance of physical layer security (PLS) in fluid antenna-aided communication systems under arbitrary correlated fading channels. In particular, it is considered that a single fixed-antenna transmitter aims to send confidential information to a legitimate receiver equipped with a planar fluid antenna system (FAS), while an eavesdropper, also taking advantage of a planar FAS, attempts to decode the desired message. For this scenario, we first present analytical expressions of the equivalent channel distributions at the legitimate user and eavesdropper by using copula, so that the obtained analytical results are valid for any arbitrarily correlated fading distributions. Then, with the help of Gauss-Laguerre quadrature, we derive compact analytical expressions for the average secrecy capacity (ASC), the secrecy outage probability (SOP), and the secrecy energy efficiency (SEE) for the FAS wiretap channel. Moreover, for exemplary purposes, we also obtain the compact expression of ASC, SOP, and SEE by utilizing the Gaussian copula under correlated Rayleigh fading channels as a special case. Eventually, numerical results indicate that applying the fluid antenna with only one activated port to PLS can guarantee more secure and reliable transmission, when compared to traditional antenna systems (TAS) exploiting maximal ratio combining (MRC) and antenna selection (AS) under selection combining (SC).
Paper Structure (18 sections, 9 theorems, 41 equations, 5 figures, 1 table)

This paper contains 18 sections, 9 theorems, 41 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related Works
  3. Motivations and Contributions
  4. Paper Organization
  5. Notations
  6. System Model
  7. Secrecy Performance Analysis
  8. Statistical Characterization
  9. Secrecy Metrics under Arbitrary Fading Channels
  10. ASC Analysis
  11. SOP Analysis
  12. SEE Analysis
  13. Secrecy Metrics under Rayleigh Fading Channels
  14. Numerical Results
  15. Conclusion
  16. ...and 3 more sections

Key Result

Theorem 1

The CDF and PDF of $g_{\mathrm{FA},i}$ at node $i$ for the FAS-aided secure communication system under arbitrary correlated fading channel channels are, respectively, given by and in which $F_{g_{1_i}}\left(r\right)$ and $f_{g_{1_i}}\left(r\right)$ are the marginal CDF and PDF of the channel gain $g_{k_i}$ with an arbitrary distribution. Besides, $c\left(.\right)$ is the copula density function

Figures (5)

  • Figure 1: The system model of a secure FAS communication system.
  • Figure 2: Secrecy metrics versus the average SNR at Bob $\bar{\gamma}_\mathrm{B}$ and transmit power $P$ for selected values of $K_\mathrm{B}$ and $W_\mathrm{B}$.
  • Figure 3: Secrecy metrics versus the number of fluid antenna ports $K_\mathrm{B}$ for different cases of $\kappa$.
  • Figure 4: Secrecy metrics versus the fluid antenna size $W_\mathrm{B}$ for different cases of $\kappa$.
  • Figure 5: Secrecy metrics versus the distance between Alice and Bob $d_\mathrm{B}$ for selected values of $d_\mathrm{E}$, $K_\mathrm{B}$, and $W_\mathrm{B}$.

Theorems & Definitions (20)

  • Theorem 1
  • proof
  • Proposition 1
  • proof
  • Proposition 2
  • proof
  • Proposition 3
  • proof
  • Remark 1
  • Remark 2
  • ...and 10 more