Dual Security for MIMO-OFDM ISAC Systems: Artificial Ghosts or Artificial Noise

TL;DR

A two-layer dual-secure ISAC framework that simultaneously protects sensing and communication against passive sensing Eves and communication Eves, without requiring their channel state information (CSI).

Abstract

Integrated sensing and communication (ISAC) enables the efficient sharing of wireless resources to support emerging applications, but it also gives rise to new sensing-based security vulnerabilities. Here, potential communication security threats whereby confidential messages intended for legitimate users are intercepted, but also unauthorized receivers (Eves) can passively exploit target echoes to infer sensing parameters without users being aware. Despite these risks, the joint protection of sensing and communication security in ISAC systems remains unexplored. To address this challenge, this paper proposes a two-layer dual-secure ISAC framework that simultaneously protects sensing and communication against passive sensing Eves and communication Eves, without requiring their channel state information (CSI). Specifically, transmit beamformers are jointly designed to inject artificial noise (AN) to introduce interference to communication Eves, while deliberately distorting the reference signal available to sensing Eves to impair their sensing capability. Furthermore, the proposed design generates artificial ghosts (AGs) with fake angle-range-velocity profiles observable by all receivers. Legitimate receivers can suppress these AGs, whereas sensing Eves cannot, thereby significantly reducing their probability of correctly detecting the true targets. Numerical results demonstrate that the proposed framework effectively enhances both communication and sensing security, while preserving the performance of communication users and legitimate sensing receivers.

Figures (9)

• Figure 1: A monostatic ISAC system with a target $l \in \mathcal{L}$, a communication user $k \in \mathcal{K}$, a bistatic sensing eavesdropper $m_r \in \mathcal{M}_r$, and a communication eavesdropper $m_c \in \mathcal{M}_c$.
• Figure 2: Illustration of the sensing security vulnerability in an ISAC system. When only the distance $d$ and the AoA angle $\theta_{l,m_r}$ are exposed, the sensing Eve can infer that the target lies somewhere along the dotted locus but cannot determine its exact position. If the AoD $\theta_{l,t}$ is also revealed, the target’s location becomes fully identifiable.
• Figure 3: The sensing SNR for BS ($\gamma_{n_c, n_s, l, B}$) versus the secrecy rate for users ($\eta_{S}$). The values of $\eta_{\mathrm{PSL}}$ is set to -25 dB and $\eta_{E} = 3$ bps/Hz.
• Figure 4: The sensing SNR for BS ($\gamma_{n_c, n_s, l, B}$) versus the secrecy rate for users ($\eta_{S}$). The values of $\eta_{\mathrm{ISL}}$ is set to -4 dB and $\eta_{E} = 5$ bps/Hz.
• Figure 5: The sensing Eve reference signal transmission rate ($\eta_E$) versus user secrecy rate ($\eta_S$).

Theorems & Definitions (2)

• Remark 1
• Remark 2