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Semantic Communication-assisted Physical Layer Security over Fading Wiretap Channels

Xidong Mu, Yuanwei Liu

TL;DR

This work addresses physical-layer security over fading wiretap channels by integrating semantic communication (SC) with conventional bit transmission. The Tx emits a superposition of semantic and bit streams, enabling the semantic component to serve as beneficial information-bearing noise that degrades the eavesdropper while remaining decodable to the Rx; the objective is the ergodic secrecy rate $\mathcal{E}=\mathbb{E}_v[[R_L(v)-R_E(v)]^+]$, optimized through joint control of the transmit power $p(v)$, power-splitting ratio $\beta(v)$, and SIC decoding order $\mu(v)$ under peak and average power constraints. The authors develop an optimal Lagrangian-dual solution (leveraging strong duality from the time-sharing property) and a low-complexity SCA-based suboptimal algorithm, demonstrating significant secrecy gains over baselines and near-optimal performance of the suboptimal approach. Key insights include explicit SINR expressions at the Rx and EVE under SIC, a logistic-approximation for semantic-rate $\varepsilon_K(\cdot)$, and iterative convexification to handle non-convexities. The results suggest practical gains for securing wireless links in future networks by embedding task-relevant semantics into the physical layer while exploiting SC as beneficial AN.

Abstract

A novel semantic communication (SC)-assisted secrecy transmission framework is proposed. In particular, the legitimate transmitter (Tx) sends the superimposed semantic and bit stream to the legitimate receiver (Rx), where the information may be eavesdropped by the malicious node (EVE). As the EVE merely has the conventional bit-oriented communication structure, the semantic signal acts as the type of beneficial information-bearing artificial noise (AN), which not only keeps strictly confidential to the EVE but also interferes with the EVE. The ergodic (equivalent) secrecy rate over fading wiretap channels is maximized by jointly optimizing the transmit power, semantic-bit power splitting ratio, and the successive interference cancellation decoding order at the Tx, subject to both the instantaneous peak and long-term average power constraints. To address this non-convex problem, both the optimal and suboptimal algorithms are developed by employing the Lagrangian dual method and the successive convex approximation method, respectively. Numerical results show that the proposed SC-assisted secrecy transmission scheme can significantly enhance the physical layer security compared to the baselines using the conventional bit-oriented communication and no-information-bearing AN. It also shows that the proposed suboptimal algorithm can achieve a near-optimal performance.

Semantic Communication-assisted Physical Layer Security over Fading Wiretap Channels

TL;DR

This work addresses physical-layer security over fading wiretap channels by integrating semantic communication (SC) with conventional bit transmission. The Tx emits a superposition of semantic and bit streams, enabling the semantic component to serve as beneficial information-bearing noise that degrades the eavesdropper while remaining decodable to the Rx; the objective is the ergodic secrecy rate , optimized through joint control of the transmit power , power-splitting ratio , and SIC decoding order under peak and average power constraints. The authors develop an optimal Lagrangian-dual solution (leveraging strong duality from the time-sharing property) and a low-complexity SCA-based suboptimal algorithm, demonstrating significant secrecy gains over baselines and near-optimal performance of the suboptimal approach. Key insights include explicit SINR expressions at the Rx and EVE under SIC, a logistic-approximation for semantic-rate , and iterative convexification to handle non-convexities. The results suggest practical gains for securing wireless links in future networks by embedding task-relevant semantics into the physical layer while exploiting SC as beneficial AN.

Abstract

A novel semantic communication (SC)-assisted secrecy transmission framework is proposed. In particular, the legitimate transmitter (Tx) sends the superimposed semantic and bit stream to the legitimate receiver (Rx), where the information may be eavesdropped by the malicious node (EVE). As the EVE merely has the conventional bit-oriented communication structure, the semantic signal acts as the type of beneficial information-bearing artificial noise (AN), which not only keeps strictly confidential to the EVE but also interferes with the EVE. The ergodic (equivalent) secrecy rate over fading wiretap channels is maximized by jointly optimizing the transmit power, semantic-bit power splitting ratio, and the successive interference cancellation decoding order at the Tx, subject to both the instantaneous peak and long-term average power constraints. To address this non-convex problem, both the optimal and suboptimal algorithms are developed by employing the Lagrangian dual method and the successive convex approximation method, respectively. Numerical results show that the proposed SC-assisted secrecy transmission scheme can significantly enhance the physical layer security compared to the baselines using the conventional bit-oriented communication and no-information-bearing AN. It also shows that the proposed suboptimal algorithm can achieve a near-optimal performance.
Paper Structure (12 sections, 2 theorems, 25 equations, 3 figures)

This paper contains 12 sections, 2 theorems, 25 equations, 3 figures.

Table of Contents

  1. Introduction
  2. System Model and Problem Formulation
  3. SC-assisted Secrecy Transmission
  4. Achievable Communication Rate at the Rx
  5. Achievable Communication Rate at the EVE
  6. Secrecy Communication Rate
  7. Problem Formulation
  8. Proposed Solutions
  9. Optimal Solution to Problem \ref{['Problem']}
  10. Suboptimal Solution to Problem \ref{['Problem']}
  11. Numerical Results
  12. Conclusions

Key Result

Lemma 1

For problem Problem given the APCs $\overline P_a$ and $\overline P_b$, the corresponding optimal solutions are denoted by $\left\{ {{p_a}\left( v \right),{\beta _a}\left( v \right),{\mu _a}\left( v \right)} \right\}$ and $\left\{ {{p_b}\left( v \right),{\beta _b}\left( v \right),{\mu _b}\left( v \r where ${\cal E}_i={{\mathbb{E}}_v}\left[ {\cal R}\left( {p_i \left( v \right),\beta_i \left( v \ri

Figures (3)

  • Figure 1: The proposed SC-assisted secrecy transmission framework.
  • Figure 2: Ergodic secrecy rate of different transmission schemes versus the APC.
  • Figure 3: Ergodic secrecy rate of different semantic encoder schemes versus the APC.

Theorems & Definitions (5)

  • Remark 1
  • Lemma 1
  • proof
  • Lemma 2
  • proof