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Proactive Eavesdropping in Relay Systems via Trajectory and Power Optimization

Qian Dan, Hongjiang Lei, Ki-Hong Park, Weijia Lei, Gaofeng Pan

TL;DR

The paper addresses proactive eavesdropping in a UAV-enabled cooperative network by maximizing the average eavesdropping rate $AER$ through joint design of the aerial eavesdropper's trajectory and jamming power, under the constraint $R_E[n]\ge R_D[n]$ for successful surveillance. It introduces a two-stage optimization framework based on block coordinate descent (BCD) and successive convex approximation (SCA), first for a 2D trajectory with horizontal position and power subproblems, then extending to a 3D trajectory with altitude optimization. The proposed algorithms decompose the nonconvex problem into convex subproblems solved iteratively, demonstrating significant $AER$ gains and fast convergence in simulations, and revealing how proximity to the suspicious link reduces required jamming while enabling more effective eavesdropping. The work highlights the potential of UAV-based proactive surveillance in LoS-enabled cooperative networks and points to future extensions to multi-antenna and FD configurations for broader applicability.

Abstract

Wireless relays can effectively extend the transmission range of information. However, if relay technology is utilized unlawfully, it can amplify potential harm. Effectively surveilling illegitimate relay links poses a challenging problem. Unmanned aerial vehicles (UAVs) can proactively surveil wireless relay systems due to their flexible mobility. This work focuses on maximizing the eavesdropping rate (ER) of UAVs by jointly optimizing the trajectory and jamming power. To address this challenge, we propose a new iterative algorithm based on block coordinate descent and successive convex approximation technologies. Simulation results demonstrate that the proposed algorithm significantly enhances the ER through trajectory and jamming power optimization.

Proactive Eavesdropping in Relay Systems via Trajectory and Power Optimization

TL;DR

The paper addresses proactive eavesdropping in a UAV-enabled cooperative network by maximizing the average eavesdropping rate through joint design of the aerial eavesdropper's trajectory and jamming power, under the constraint for successful surveillance. It introduces a two-stage optimization framework based on block coordinate descent (BCD) and successive convex approximation (SCA), first for a 2D trajectory with horizontal position and power subproblems, then extending to a 3D trajectory with altitude optimization. The proposed algorithms decompose the nonconvex problem into convex subproblems solved iteratively, demonstrating significant gains and fast convergence in simulations, and revealing how proximity to the suspicious link reduces required jamming while enabling more effective eavesdropping. The work highlights the potential of UAV-based proactive surveillance in LoS-enabled cooperative networks and points to future extensions to multi-antenna and FD configurations for broader applicability.

Abstract

Wireless relays can effectively extend the transmission range of information. However, if relay technology is utilized unlawfully, it can amplify potential harm. Effectively surveilling illegitimate relay links poses a challenging problem. Unmanned aerial vehicles (UAVs) can proactively surveil wireless relay systems due to their flexible mobility. This work focuses on maximizing the eavesdropping rate (ER) of UAVs by jointly optimizing the trajectory and jamming power. To address this challenge, we propose a new iterative algorithm based on block coordinate descent and successive convex approximation technologies. Simulation results demonstrate that the proposed algorithm significantly enhances the ER through trajectory and jamming power optimization.
Paper Structure (14 sections, 1 theorem, 44 equations, 8 figures, 3 tables, 2 algorithms)

This paper contains 14 sections, 1 theorem, 44 equations, 8 figures, 3 tables, 2 algorithms.

Table of Contents

  1. Introduction
  2. Background and Related Works
  3. Motivation and Contributions
  4. Organization
  5. System Model
  6. Problem Formulation
  7. Proposed Algorithm for Problem $\mathcal{P}_{1}$
  8. Subproblem 1: Optimizing horizontal position
  9. Subproblem 2: Optimizing Jamming Power
  10. Joint Optimization 3D Trajectory and Jamming Power of $E$
  11. Subproblem 3: Optimizing Vertical Trajectory
  12. Numerical Results and Discussion
  13. Conclusion
  14. Proof of Lemma 1

Key Result

Lemma 1

For given $c_1 > 0, c_2 > 0,c_3 > 0,c_4 > 0$, $f = {\log _2}\left({c_1} + {c_2}{x^{ - 1}} + {c_3}{y^{ - 1}} + {c_4}{x^{ - \frac{1}{2}}}{y^{ - \frac{1}{2}}}\right)$ is a convex function.

Figures (8)

  • Figure 1: System model consisting of an illegal terrestrial source $\left( S \right)$, a ground destination $\left( D \right)$, an AF relay $\left( R \right)$, and an aerial FD eavesdropper $\left( E \right)$.
  • Figure 2: Scenario 1.
  • Figure 3: Scenario 2.
  • Figure 4: AER for varying $P$ and $T$.
  • Figure 5: The 3D trajectory of $E$.
  • ...and 3 more figures

Theorems & Definitions (2)

  • Lemma 1
  • proof