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.

翻译：大规模多输入多输出（MIMO）已成为5G及未来通信的关键使能技术，带来了前所未有的能量与频谱效率提升。然而，在这些系统中确保通信安全仍面临挑战，尤其是在基站无法获知其信道状态信息的被动窃听者存在的情况下。物理层安全（PLS）通过利用无线信道固有的随机性，提供了一种前景广阔的解决方案；但其在大规模MIMO中的有效性高度依赖于资源分配与传输策略。本文研究了在存在被动窃听者时，最大比传输（MRT）、迫零（ZF）以及人工噪声（AN）辅助波束成形等安全传输方案的性能。通过大量蒙特卡洛仿真，评估了不同系统参数（如天线数量、信噪比（SNR）、功率分配）下的关键性能指标，包括能量效率、安全中断概率和安全和速率。研究结果旨在为不同PLS策略的优势与局限提供对比性见解，并指明未来6G网络中设计可扩展、高能效且鲁棒的安全传输技术的开放研究方向。