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Secure Backscatter Communications Through RIS: Modeling and Performance

Masoud Kaveh, Farshad Rostami Ghadi, Zhao Li, Zheng Yan, Riku Jantti

TL;DR

This work analyzes secrecy performance of RIS-aided backscatter communication under Fisher-Snedecor $\mathcal{F}$ fading, addressing scenarios with and without direct links. It develops compact analytical expressions for the PDFs and CDFs of the legitimate and eavesdropper SNRs, and derives ASC and SOP using multivariate Fox's $H$-functions, complemented by high-SNR asymptotics via the residue method. The results, validated by Monte-Carlo simulations, show that RIS substantially improves secrecy performance over conventional BC, highlighting RIS phase-control and RIS-element scaling as key levers under realistic fading and shadowing. The study provides a rigorous, tractable framework for secure BC design in low-power IoT settings and paves the way for RIS-driven PLS in next-generation wireless networks.

Abstract

Backscatter communication (BC) has emerged as a pivotal wireless communication paradigm owing to its low-power and cost-effective characteristics. However, BC faces various challenges from its low signal detection rate to its security vulnerabilities. Recently, reconfigurable intelligent surfaces (RIS) have surfaced as a transformative technology addressing power and communication performance issues in BC. However, the potential of RIS in addressing the security challenges of BC remains uncharted. This paper investigates the secrecy performance of RIS-aided BC, where all channels are distributed according to the Fisher-Snedecor $\mathcal{F}$ distribution. Specifically, we consider a RIS with $N$ reflecting elements to help a backscatter device (BD) establish a smart environment and enhance the secrecy performance in BC. Due to the nature of BC systems, our analysis considers two possible scenarios (i) in the absence of direct links and (ii) in the presence of direct links. In both cases, we first derive compact analytical expressions of the probability density function (PDF) and cumulative distribution function (CDF) for the received signal-to-noise ratio (SNR) at both a legitimate receiver and an eavesdropper. Then, to analyze the secrecy performance, we further derive analytical expressions of the average secrecy capacity (ASC) and secrecy outage probability (SOP) for both mentioned scenarios. In addition, regarding the importance of system behavior in a high SNR regime, we provide an asymptotic analysis of the SOP and ASC. Eventually, the Monte-Carlo simulation is used to validate the analytical results, revealing that utilizing RIS can greatly improve the secrecy performance of the BC system relative to traditional BC setups that do not incorporate RIS.

Secure Backscatter Communications Through RIS: Modeling and Performance

TL;DR

This work analyzes secrecy performance of RIS-aided backscatter communication under Fisher-Snedecor fading, addressing scenarios with and without direct links. It develops compact analytical expressions for the PDFs and CDFs of the legitimate and eavesdropper SNRs, and derives ASC and SOP using multivariate Fox's -functions, complemented by high-SNR asymptotics via the residue method. The results, validated by Monte-Carlo simulations, show that RIS substantially improves secrecy performance over conventional BC, highlighting RIS phase-control and RIS-element scaling as key levers under realistic fading and shadowing. The study provides a rigorous, tractable framework for secure BC design in low-power IoT settings and paves the way for RIS-driven PLS in next-generation wireless networks.

Abstract

Backscatter communication (BC) has emerged as a pivotal wireless communication paradigm owing to its low-power and cost-effective characteristics. However, BC faces various challenges from its low signal detection rate to its security vulnerabilities. Recently, reconfigurable intelligent surfaces (RIS) have surfaced as a transformative technology addressing power and communication performance issues in BC. However, the potential of RIS in addressing the security challenges of BC remains uncharted. This paper investigates the secrecy performance of RIS-aided BC, where all channels are distributed according to the Fisher-Snedecor distribution. Specifically, we consider a RIS with reflecting elements to help a backscatter device (BD) establish a smart environment and enhance the secrecy performance in BC. Due to the nature of BC systems, our analysis considers two possible scenarios (i) in the absence of direct links and (ii) in the presence of direct links. In both cases, we first derive compact analytical expressions of the probability density function (PDF) and cumulative distribution function (CDF) for the received signal-to-noise ratio (SNR) at both a legitimate receiver and an eavesdropper. Then, to analyze the secrecy performance, we further derive analytical expressions of the average secrecy capacity (ASC) and secrecy outage probability (SOP) for both mentioned scenarios. In addition, regarding the importance of system behavior in a high SNR regime, we provide an asymptotic analysis of the SOP and ASC. Eventually, the Monte-Carlo simulation is used to validate the analytical results, revealing that utilizing RIS can greatly improve the secrecy performance of the BC system relative to traditional BC setups that do not incorporate RIS.
Paper Structure (42 sections, 10 theorems, 73 equations, 8 figures, 1 table)

This paper contains 42 sections, 10 theorems, 73 equations, 8 figures, 1 table.

Table of Contents

  1. Introduction
  2. Research Gaps and Motivations
  3. Contributions
  4. Organization and Notations
  5. Related Works
  6. PLS Performance Analysis for BC Systems
  7. Enhancing PLS Performance Using RIS
  8. RIS-Aided BC Systems
  9. System Model
  10. Without Direct Links
  11. With Direct Links
  12. SNR Distribution
  13. Without Direct Links
  14. Legitimate link
  15. Eavesdropper link
  16. ...and 27 more sections

Key Result

Theorem 1

Assuming all channels follow the Fisher-Snedecor $\mathcal{F}$ fading distribution, the PDF and CDF of $\gamma_R$ without direct links are given by where $\mathcal{G}=\frac{ 2^{\frac{2c-3}{2}}{\bar{y}_1}^\frac{c-1}{d} \mathcal{C}}{\sqrt{2\pi} \bar{\gamma}_R {\bar{y}_1}^\frac{c+1}{2} d^{c+1} \Gamma(c+1)}$ and $\bar{y}_1=\frac{P_S}{{d}^\chi_{T\Theta}{d}^\chi_{\Theta R}{\sigma}^2_R}$.

Figures (8)

  • Figure 1: The system model of RIS-aided BC.
  • Figure 2: The simulation setup.
  • Figure 3: ASC versus $\Bar{\gamma}_{R_2}$ for different numbers of RIS elements.
  • Figure 4: ASC versus $\Bar{\gamma}_{R_2}$ for different values of $\Bar{\gamma}_{E_2}$ and $N=10$.
  • Figure 5: ASC versus ${S_R}$ for different values of $m_i$.
  • ...and 3 more figures

Theorems & Definitions (22)

  • Theorem 1
  • proof
  • Theorem 2
  • proof
  • Theorem 3
  • proof
  • Theorem 4
  • proof
  • Theorem 5
  • proof
  • ...and 12 more