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arXiv · 2408.17169

Secure Transmission in Cell-Free Massive MIMO under Active Eavesdropping

Yasseen Sadoon Atiya·Zahra Mobini·Hien Quoc Ngo·Michail Matthaiou
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Abstract

We study secure communications in cell-free massive multiple-input multiple-output (CF-mMIMO) systems with multi-antenna access points (APs) and protective partial zero-forcing (PPZF) precoding. In particular, we consider an active eavesdropping attack, where an eavesdropper contaminates the uplink channel estimation phase by sending an identical pilot sequence with a legitimate user of interest. We formulate an optimization problem for maximizing the received signal-to-noise ratio (SINR) at the legitimate user, subject to a maximum allowable SINR at the eavesdropper and maximum transmit power at each AP, while guaranteeing specific SINR requirements on other legitimate users. The optimization problem is solved using a path-following algorithm. We also propose a large-scale-based greedy AP selection scheme to improve the secrecy spectral efficiency (SSE). Finally, we propose a simple method for identifying the presence of an eavesdropper within the system. Our findings show that PPZF can substantially outperform the conventional maximum-ratio transmission (MRT) scheme by providing around 2-fold improvement in the SSE compared to the MRT scheme. More importantly, for PPZF precoding scheme, our proposed AP selection can achieve a remarkable SSE gain of up to 220%, while our power optimization approach can provide an additional gain of up to 55% compared with a CF-mMIMO system with equal power allocation.

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Yasseen Sadoon Atiya, Zahra Mobini, Hien Quoc Ngo, Michail Matthaiou. 2024-08-30. Secure Transmission in Cell-Free Massive MIMO under Active Eavesdropping. https://arxiv.org/abs/2408.17169

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