---
title: "Wireless Backdoor Attack and Defense for Semantic Communications over Multiple Access Channel"
source: "arXiv AI/CL/LG（论文）"
source_tier: "t2"
url: "https://arxiv.org/abs/2606.30595v1"
permalink: "https://feed.astralor.com/items/itm_23610d1dca863ae8eb173084"
published: "2026-06-29T17:36:09.000Z"
score: 55
channel: "tech"
tags: ["Backdoor Attack","multiple access channel","wireless security","Semantic Communication","defense mechanism"]
---

# Wireless Backdoor Attack and Defense for Semantic Communications over Multiple Access Channel

## At a glance

This paper studies new security vulnerabilities in multi-user shared-access wireless networks for semantic communications. For a scenario where two transmitters communicate with a common receiver over a multiple access channel, a selective over-the-air backdoor attack is proposed: the adversary injects a low-power trigger waveform into the shared received signal during training, and by transmitting the trigger again during testing, selectively manipulates the semantic inference of one transmitter while minimally affecting the other. A trigger-aware defense mechanism is also developed to preserve correct semantic labels under trigger-contaminated observations. Experiments demonstrate both the effectiveness of the attack and the feasibility of the defense.

## Key points

- Proposes a selective over-the-air backdoor attack for semantic communications over multiple access channel
- Attack injects low-power trigger waveform during training and selectively manipulates single-user semantic inference during testing
- Develops a trigger-aware defense mechanism to preserve correct semantic labels under trigger contamination
- Experiments verify attack threat and defense effectiveness

## Full text

Semantic communication (SemCom) aims to preserve semantic meaning and task-oriented information beyond conventional message recovery over wireless channels. The adoption of SemCom in shared-access wireless networks introduces new vulnerabilities for multi-user semantic inference. This paper considers a SemCom system for two transmitters communicating with a common receiver over a multiple access channel. Each transmitter maps source information into latent semantic representations, while the receiver jointly reconstructs and classifies the semantic information for both transmitters. A selective over-the-air backdoor (Trojan) attack is presented in which an adversary transmits a low-power trigger waveform over the air and injects it into the shared received signal during training. By transmitting the trigger again during testing, this stealthy, low-power attack selectively manipulates the semantic inference for one transmitter while minimally affecting the inference of the other transmitter. To mitigate this vulnerability, a trigger-aware defense mechanism is developed to preserve correct semantic labels under trigger-contaminated wireless observations. The results demonstrate both the vulnerability of shared-access SemCom systems to selective over-the-air backdoor attacks and the effectiveness of trigger-aware robust training for semantic protection.

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