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Performance Analysis of Fluid Antenna-aided Backscatter Communications Systems

Farshad Rostami Ghadi, Masoud Kaveh, Kai-Kit Wong

TL;DR

This work analyzes backscatter communications when a fluid antenna (FA) reader with K ports dynamically selects the best port to maximize the product of forward and backscatter channels. It develops a copula-based statistical framework to characterize the maximum of K correlated product channels, deriving closed-form outage probability (OP) and delay outage rate (DOR) under correlated Rayleigh fading and providing high-SNR asymptotics. The analysis reveals that increasing the FA port separation (W) and/or the number of ports (K) substantially improves reliability and latency performance compared with a traditional single-antenna reader. The framework and results offer practical guidance for deploying FA-enabled BC in 6G/URLLC scenarios where low latency and high reliability are critical.

Abstract

This paper studies the performance of backscatter communications (BC) over emerging fluid antenna (FA) technology. In particular, a single-antenna source sends information to a FA reader through the wireless forward (i.e., source-to-tag) and backscatter (tag-to-reader) channels. For the considered BC, we first derive the cumulative distribution function (CDF) of the equivalent channel at the FA receiver, and then we obtain closed-form expressions of the outage probability (OP) and delay outage rate (DOR) under a correlated Rayleigh distribution. Moreover, in order to gain more insights into the system performance, we present analytical expressions of the OP and DOR at the high SNR regime. Numerical results indicate that considering the FA at the reader can significantly improve the performance of BC in terms of the OP and DOR compared with a single-antenna reader.

Performance Analysis of Fluid Antenna-aided Backscatter Communications Systems

TL;DR

This work analyzes backscatter communications when a fluid antenna (FA) reader with K ports dynamically selects the best port to maximize the product of forward and backscatter channels. It develops a copula-based statistical framework to characterize the maximum of K correlated product channels, deriving closed-form outage probability (OP) and delay outage rate (DOR) under correlated Rayleigh fading and providing high-SNR asymptotics. The analysis reveals that increasing the FA port separation (W) and/or the number of ports (K) substantially improves reliability and latency performance compared with a traditional single-antenna reader. The framework and results offer practical guidance for deploying FA-enabled BC in 6G/URLLC scenarios where low latency and high reliability are critical.

Abstract

This paper studies the performance of backscatter communications (BC) over emerging fluid antenna (FA) technology. In particular, a single-antenna source sends information to a FA reader through the wireless forward (i.e., source-to-tag) and backscatter (tag-to-reader) channels. For the considered BC, we first derive the cumulative distribution function (CDF) of the equivalent channel at the FA receiver, and then we obtain closed-form expressions of the outage probability (OP) and delay outage rate (DOR) under a correlated Rayleigh distribution. Moreover, in order to gain more insights into the system performance, we present analytical expressions of the OP and DOR at the high SNR regime. Numerical results indicate that considering the FA at the reader can significantly improve the performance of BC in terms of the OP and DOR compared with a single-antenna reader.
Paper Structure (9 sections, 4 theorems, 20 equations, 4 figures)

This paper contains 9 sections, 4 theorems, 20 equations, 4 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. Performance Analysis
  4. Statistical Characterization
  5. OP Analysis
  6. DOR Analysis
  7. Asymptotic Analysis
  8. Numerical Results
  9. Conclusion

Key Result

Proposition 1

The CDF of $g_\mathrm{FA}=\max\left\{g_{\mathrm{p},k}\dots, g_{\mathrm{p},k}\right\}$ for the considered FA-aided BC is given by in which $\mathcal{K}_1\left(\cdot\right)$ denotes the first-order modified Bessel function of the second kind and $\theta\in\left(0,\infty\right)$ is the dependence parameter so that $\theta\rightarrow 0$ represents the independent case.

Figures (4)

  • Figure 1: The system model represents FA-aided BC.
  • Figure 2: Performance of (a) OP and (b) DOR versus average SNR $\bar{\gamma}$ for selected values of FA size $W$.
  • Figure 3: Performance of (a) OP and (b) DOR versus average SNR $\bar{\gamma}$ for selected values of FA ports $K$.
  • Figure 4: DOR versus amount of data $R$ for selected of values $W$ and $K$.

Theorems & Definitions (8)

  • Proposition 1
  • proof
  • Proposition 2
  • proof
  • Proposition 3
  • proof
  • Corollary 1
  • proof