Joint Power Optimization and AP Selection for Secure Cell-Free Massive MIMO

TL;DR

This paper proposes a joint power control and AP selection scheme for secure cell-free massive MIMO systems under active eavesdropping, significantly improving secrecy spectral efficiency compared to heuristic methods.

Contribution

It introduces a novel joint optimization framework and an efficient APG-based solution to enhance security in CF-mMIMO systems against active eavesdropping.

Findings

Proposed method outperforms heuristic approaches in secrecy SE.

50% likely SSE is 265% higher than baseline schemes.

Efficient low-complexity algorithm achieves significant security gains.

Abstract

In this paper, we investigate joint power control and access point (AP) selection scheme in a cell-free massive multiple-input multiple-output (CF-mMIMO) system under an active eavesdropping attack, where an eavesdropper tries to overhear the signal sent to one of the legitimate users by contaminating the uplink channel estimation. We formulate a joint optimization problem to minimize the eavesdropping spectral efficiency (SE) while guaranteeing a given SE requirement at legitimate users. The challenging formulated problem is converted into a more tractable form and an efficient low-complexity accelerated projected gradient (APG)-based approach is proposed to solve it. Our findings reveal that the proposed joint optimization approach significantly outperforms the heuristic approaches in terms of secrecy SE (SSE). For instance, the $50\%$ likely SSE performance of the proposed approach is $265\%$ higher than that of equal power allocation and random AP selection scheme.