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Movable Antenna Array Aided Ultra Reliable Covert Communications

Yida Wang, Guojie Hu, Xiaoling Hu, Xingbo Lu, Yuzhen Huang

TL;DR

This work addresses covert communications with movable antenna (MA) arrays under general noise uncertainty. It develops closed-form analyses for the sum of detection errors $\xi^*$ and the outage probability, demonstrating that adjusting MA positions can achieve near-perfect covertness and ultra reliability. An MRT-based design is used to fix beamforming while a lightweight Discrete Projected Gradient Descent (DPGD) optimizes antenna positions, yielding a decoupled solution with a simple closed-form power update $P_a^*$. Numerical results show MA significantly expands the steerable region and outperforms fixed-position antennas, offering a practical path to ultra-reliable covert links in slowly varying channels.

Abstract

In this paper, we construct a framework of the movable antenna (MA) aided covert communication shielded by the general noise uncertainty for the first time. According to the analysis performance on the derived closed-form expressions of the sum of the probabilities of the detection errors and the communication outage probability, the perfect covertness and the ultra reliability can be achieved by adjusting the antenna position in the MA array. Then, we formulate the communication covertness maximization problem with the constraints of the ultra reliability and the independent discrete movable position to optimize the transmitter's parameter. With the maximal ratio transmitting (MRT) design for the beamforming, we solve the closed-form optimal information transmit power and design a lightweight discrete projected gradient descent (DPGD) algorithm to determine the optimal antenna position. The numerical results show that the optimal achievable covertness and the feasible region of the steering angle with the MA array is significant larger than the one with the fixed-position antenna (FPA) array.

Movable Antenna Array Aided Ultra Reliable Covert Communications

TL;DR

This work addresses covert communications with movable antenna (MA) arrays under general noise uncertainty. It develops closed-form analyses for the sum of detection errors and the outage probability, demonstrating that adjusting MA positions can achieve near-perfect covertness and ultra reliability. An MRT-based design is used to fix beamforming while a lightweight Discrete Projected Gradient Descent (DPGD) optimizes antenna positions, yielding a decoupled solution with a simple closed-form power update . Numerical results show MA significantly expands the steerable region and outperforms fixed-position antennas, offering a practical path to ultra-reliable covert links in slowly varying channels.

Abstract

In this paper, we construct a framework of the movable antenna (MA) aided covert communication shielded by the general noise uncertainty for the first time. According to the analysis performance on the derived closed-form expressions of the sum of the probabilities of the detection errors and the communication outage probability, the perfect covertness and the ultra reliability can be achieved by adjusting the antenna position in the MA array. Then, we formulate the communication covertness maximization problem with the constraints of the ultra reliability and the independent discrete movable position to optimize the transmitter's parameter. With the maximal ratio transmitting (MRT) design for the beamforming, we solve the closed-form optimal information transmit power and design a lightweight discrete projected gradient descent (DPGD) algorithm to determine the optimal antenna position. The numerical results show that the optimal achievable covertness and the feasible region of the steering angle with the MA array is significant larger than the one with the fixed-position antenna (FPA) array.
Paper Structure (11 sections, 1 theorem, 21 equations, 4 figures, 1 algorithm)

This paper contains 11 sections, 1 theorem, 21 equations, 4 figures, 1 algorithm.

Table of Contents

  1. Introduction
  2. System Model
  3. Considered Scenario and Adopted Assumptions
  4. Activity Detection at Willie
  5. Analysis on Performance Metrics for Ultra Reliable Covert Communications
  6. Communication Covertness Performance
  7. Communication Outage Probability
  8. Ultra Reliable Covert Communications Design
  9. Numerical Results
  10. Conclusion
  11. Acknowledgment

Key Result

Theorem 1

The Willie's minimum sum of the probabilities of detection errors is given by where $\kappa_0=\left( {\rho - \frac{1}{\rho }} \right){\sigma _0^2}$.

Figures (4)

  • Figure 1: The system model of covert communications aided by the movable antenna array.
  • Figure 2: The achievable covertness versus the Willie's steering angle $\theta_w$ for different $R$ with $N\!=\!3$, $K_n\!=\!+\infty$, $L_0=10$ and $\rho=3$ dB.
  • Figure 3: The achievable covertness versus the number of the antenna $N$ for different $\rho$ with $\theta_w=0.01\pi/2$, $K_n=+\infty$, $L_0=2$, and $R=1$.
  • Figure 4: The achievable covertness versus the transmission rate $R$ for different $L_0$ and $K_n=K$ with $\theta_w=0.01\pi/2$, $N=4$, and $\rho=3$ dB.

Theorems & Definitions (1)

  • Theorem 1