Physical Layer Security in Massive MIMO: Challenges and Open Research Directions Against Passive Eavesdroppers

TL;DR

This paper evaluates physical layer security strategies in massive MIMO systems against passive eavesdroppers, highlighting their performance and open research challenges for future 6G networks.

Contribution

It provides a comparative analysis of secure transmission schemes in massive MIMO, emphasizing their strengths, limitations, and future research directions.

Findings

Artificial Noise improves secrecy sum rate under certain conditions.

Zero-Forcing beamforming reduces secrecy outage probability.

Energy efficiency varies significantly with system parameters.

Abstract

Massive Multiple-Input Multiple-Output (MIMO) has become a crucial enabling technology for 5G and beyond, providing previously unheard-of increases in energy and spectrum efficiency. It is still difficult to guarantee secure communication in these systems, particularly when it comes to passive eavesdroppers whose base station is unaware of their channel state information. By taking advantage of the inherent randomness of wireless channels, Physical Layer Security (PLS) offers a promising paradigm; however, its efficacy in massive MIMO is heavily reliant on resource allocation and transmission strategies. In this work, the performance of secure transmission schemes, such as Maximum Ratio Transmission (MRT), Zero-Forcing (ZF), and Artificial Noise (AN)-aided beamforming, is examined when passive eavesdroppers are present. This work will use extensive Monte Carlo simulations to assess important performance metrics such as energy efficiency, secrecy outage probability, and secrecy sum rate under different system parameters (e.g., number of antennas, Signal-to-Noise Ratio (SNR), power allocation). The results aim to provide comparative insight into the strengths and limitations of different PLS strategies and to highlight open research directions to design scalable, energy-efficient, and robust secure transmission techniques in future 6G networks.