Hybrid Beamforming and Physical Layer Security Techniques for 6G Massive MIMO Communication Systems

Abstract

The present paper provides an in-depth inquiry on the topic of hybrid beamforming and physical layer security (PLS) technologies which will suit 6G massive multiple-input multiple-output (MIMO) communication systems. The first goal is to overcome both the energy-efficient beamforming and secure transmission issue with passive eavesdroppers, which is of utmost importance in 6G networks using millimeter-wave and sub-terahertz frequencies. The author suggests a new low-complexity hybrid analog-digital design of the beam forming structure which can use a sub-array structure to decrease the number of the RF chains but still generates high spatial resolution. Artificial noise (AN) is injected at particular locations within the null space of legitimate user channels; this has the effect of compromising signal quality on the capabilities of the eavesdropper only, without interfering with targeted receivers. The system architecture proposed optimizes the AN covariance matrix, analog precoder, and digital baseband precoder together in terms of the transmit power and hardware limitations. Extensive Monte-Carlo simulations under realistic propagation conditions demonstrate that the proposed approach has significantly better secrecy rate (an enhancement of up to 35% compared to conventional hybrid beamforming techniques) and a portion of energy efficiency is maintained with minimal negative impacts on robustness of the system in case of imperfect channel state information (CSI). The results attest to the effectiveness of the methodology in terms of practical and scalable 6G applications. Future extensions of the framework will be based on AI-powered adaptive beam choice and the incorporation of reconfigurable intelligent surfaces (RIS) to improve the physics-layer security.