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Enhancing Covert Communication in Relay Systems Using Multi-Antenna Technique

He Zhu, Huihui Wu, Wei Su, Xiaohong Jiang

TL;DR

This work addresses covert communication in a two-hop DF relay system under warden detection, and investigates the performance gains from employing multi-antenna techniques. It develops theoretical frameworks for detection error probability ($\mathcal{P}_e$) and covert throughput under both single-antenna and TAS-MRC multi-antenna configurations, using a KKT-based approach for the single-antenna case and a direct-search method for the multi-antenna case. Key contributions include closed-form DEP expressions with an optimal threshold $\tau^* = \rho \sigma_n^2$, and analytic covert-throughput formulations $\eta_s$ and $\eta_m$ that quantify gains from multi-antenna deployments under covertness, reliability, and power constraints. The results demonstrate substantial covert-performance improvements when adopting multi-antenna transceivers, with gains increasing as the antenna counts rise, offering practical insights for secure two-hop relay designs.

Abstract

This paper exploits the multi-antenna technique to enhance the covert communication performance in a relay system, where a source S conducts covert communication with a destination D via a relay R, subjecting to the detections of transmissions in the two hops from a single-antenna warden W. To demonstrate the performance gain from adopting the multi-antenna technique, we first consider the scenario when S, R and D all adopt single antenna, and apply hypothesis testing and statistics theories to develop a theoretical framework for the covert performance modeling in terms of detection error probability (DEP) and covert throughput. We then consider the scenario when S, R and D all adopt multiple antennas, and apply the hypothesis testing, statistics and matrix theories to develop corresponding theoretical framework for performance modeling. We further explore the optimal designs of the target rate and transmit power for covert throughput maximization under above both scenarios, subjecting to the constraints of covertness, reliability and transmit power. To solve the optimization problems, we employ Karushi-Kuhn-Tucker (KKT) conditions method in the single antenna scenario and a search algorithm in the multi-antenna scenario. Finally, we provide extensive numerical results to illustrate how the multi-antenna technique can enhance the covert performance in two-hop relay systems.

Enhancing Covert Communication in Relay Systems Using Multi-Antenna Technique

TL;DR

This work addresses covert communication in a two-hop DF relay system under warden detection, and investigates the performance gains from employing multi-antenna techniques. It develops theoretical frameworks for detection error probability () and covert throughput under both single-antenna and TAS-MRC multi-antenna configurations, using a KKT-based approach for the single-antenna case and a direct-search method for the multi-antenna case. Key contributions include closed-form DEP expressions with an optimal threshold , and analytic covert-throughput formulations and that quantify gains from multi-antenna deployments under covertness, reliability, and power constraints. The results demonstrate substantial covert-performance improvements when adopting multi-antenna transceivers, with gains increasing as the antenna counts rise, offering practical insights for secure two-hop relay designs.

Abstract

This paper exploits the multi-antenna technique to enhance the covert communication performance in a relay system, where a source S conducts covert communication with a destination D via a relay R, subjecting to the detections of transmissions in the two hops from a single-antenna warden W. To demonstrate the performance gain from adopting the multi-antenna technique, we first consider the scenario when S, R and D all adopt single antenna, and apply hypothesis testing and statistics theories to develop a theoretical framework for the covert performance modeling in terms of detection error probability (DEP) and covert throughput. We then consider the scenario when S, R and D all adopt multiple antennas, and apply the hypothesis testing, statistics and matrix theories to develop corresponding theoretical framework for performance modeling. We further explore the optimal designs of the target rate and transmit power for covert throughput maximization under above both scenarios, subjecting to the constraints of covertness, reliability and transmit power. To solve the optimization problems, we employ Karushi-Kuhn-Tucker (KKT) conditions method in the single antenna scenario and a search algorithm in the multi-antenna scenario. Finally, we provide extensive numerical results to illustrate how the multi-antenna technique can enhance the covert performance in two-hop relay systems.
Paper Structure (8 sections, 4 theorems, 41 equations, 1 figure)

This paper contains 8 sections, 4 theorems, 41 equations, 1 figure.

Table of Contents

  1. Introduction
  2. System Model and Preliminaries
  3. Transmission Scheme in Single-antenna Scenario
  4. Transmission Scheme in Multi-antenna Scenario
  5. Detection Scheme at Warden
  6. Covert Performance Analysis
  7. DEP in Single-antenna and Multi-antenna Scenarios
  8. Covert Throughput in Single-antenna Scenario

Key Result

Lemma 1

For the concerned two-hop relay system with transmit power $P_{ S}$ for $S$, noise uncertainty $\rho$ and nominal noise power $\sigma_n^2$ of the system, for a given detection threshold $\tau$ at $W$, the DEP ${\mathcal{P}_e}^{(1)}$ in the first time slot of single/multiple antenna scenarios can be

Figures (1)

  • Figure 1: Two-hop relay systems.

Theorems & Definitions (4)

  • Lemma 1
  • Lemma 2
  • Theorem 1
  • Theorem 2