Extremely large-scale multiple-input and multiple-output (XL-MIMO) is one of the most promising key technologies for the coming sixth generation wireless communications. Considering passive eavesdropping threats, the influence of near-field channel characteristics of uplink multi-user XL-MIMO systems on the physical layer security schemes are analyzed in this paper. Then, a comprehensive survey of physical layer encrypted methods and low complexity detection methods is presented. Conclusively, it is pointed out that the study on low complexity and high reliability modulation encrypted methods based on near field channel characteristics for uplink multi-user XL-MIMO systems has very important research value for the next generation's green security communications. Some corresponding future potential research works for low complexity physical layer security schemes based on channel characteristics of near-field XL-MIMO systems are also presented in this paper.
Extremely large-scale multiple-input and multiple-output (XL-MIMO) is one of the most promising key technologies for the coming sixth generation wireless communications. Considering passive eavesdropping threats, the influence of near-field channel characteristics of uplink multi-user XL-MIMO systems on the physical layer security schemes are analyzed in this paper. Then, a comprehensive survey of physical layer encrypted methods and low complexity detection methods is presented. Conclusively, it is pointed out that the study on low complexity and high reliability modulation encrypted methods based on near field channel characteristics for uplink multi-user XL-MIMO systems has very important research value for the next generation's green security communications. Some corresponding future potential research works for low complexity physical layer security schemes based on channel characteristics of near-field XL-MIMO systems are also presented in this paper.
The open nature of radio propagation enables ubiquitous wireless communication. This allows for seamless data transmission. However, unauthorized users may pose a threat to the security of the data being transmitted to authorized users. This gives rise to network vulnerabilities such as hacking, eavesdropping, and jamming of the transmitted information. Physical layer security (PLS) has been identified as one of the promising security approaches to safeguard the transmission from eavesdroppers in a wireless network. It is an alternative to the computationally demanding and complex cryptographic algorithms and techniques. PLS has continually received exponential research interest owing to the possibility of exploiting the characteristics of the wireless channel. One of the main characteristics includes the random nature of the transmission channel. The aforesaid nature makes it possible for confidential and authentic signal transmission between the sender and the receiver in the physical layer. We start by introducing the basic theories of PLS, including the wiretap channel, information-theoretic security, and a brief discussion of the cryptography security technique. Furthermore, an overview of multiple-input multiple-output (MIMO) communication is provided. The main focus of our review is based on the existing key-less PLS optimization techniques, their limitations, and challenges. The paper also looks into the promising key research areas in addressing these shortfalls. Lastly, a comprehensive overview of some of the recent PLS research in 5G and 6G technologies of wireless communication networks is provided.
Extremely large-scale arrays (XL-arrays) have emerged as a key enabler in achieving the unprecedented performance requirements of future wireless networks, leading to a significant increase in the range of the near-field region. This transition necessitates the spherical wavefront model for characterizing the wireless propagation rather than the far-field planar counterpart, thereby introducing extra degrees-of-freedom (DoFs) to wireless system design. In this paper, we explore the beam focusing-based physical layer security (PLS) in the near field, where multiple legitimate users and one eavesdropper are situated in the near-field region of the XL-array base station (BS). First, we consider a special case with one legitimate user and one eavesdropper to shed useful insights into near-field PLS. In particular, it is shown that 1) Artificial noise (AN) is crucial to near-fieldsecurity provisioning, transforming an insecure system to a secure one; 2) AN can yield numeroussecurity gains, which considerably enhances PLS in the near field as compared to the case without AN taken into account. Next, for the general case with multiple legitimate users, we propose an efficient low-complexity approach to design the beamforming with AN to guarantee near-field secure transmission. Specifically, the low-complexity approach is conceived starting by introducing the concept ofinterference domainto capture the inter-user interference level, followed by athree-step identification frameworkfor designing the beamforming. Finally, numerical results reveal that 1) the PLS enhancement in the near field is pronounced thanks to the additional spatial DoFs; 2) the proposed approach can achieve close performance to that of the computationally-extensive conventional method yet with a significantly lower computational complexity.
Physical-layer security is emerging approach that can benefit conventional encryption methods. The main idea of physical layer security is to take advantage of the features of the wireless channel and its impairments in order to ensure secure communication in the physical layer. This paper provides a comprehensive review of information-theoretic measures of the secrecy performance in physical layer security. In addition, our work survey research about physical layer security over several enabling 5G technologies, such as massive multiple-input multiple-output, millimeter wave communications, heterogeneous networks, and full-duplex, including the key concepts of each of the aforementioned technologies. Finally, future research directions and technical challenges of physical layer security are identified.
Physical-layer security is emerging approach that can benefit conventional encryption methods. The main idea of physical layer security is to take advantage of the features of the wireless channel and its impairments in order to ensure secure communication in the physical layer. This paper provides a comprehensive review of information-theoretic measures of the secrecy performance in physical layer security. In addition, our work survey research about physical layer security over several enabling 5G technologies, such as massive multiple-input multiple-output, millimeter wave communications, heterogeneous networks, and full-duplex, including the key concepts of each of the aforementioned technologies. Finally, future research directions and technical challenges of physical layer security are identified.
The next generation of communication systems are expected to operate at high frequency bands such as millimetre wave (mmWave) and terahertz (THz) bands, and use extremely large-scale multiple-input-multiple-output (XL-MIMO). This brings a paradigm shift from far-field to near-field communications. In this paper, we investigate physical-layer key generation in near-field XL-MIMO communications and focus on the most challenging line-of-sight (LoS) propagation scenario. To be specific, we introduce artificial randomness to enhance secret key generation and enable theoretical analysis of secret key rate (SKR). We provide the zero-forcing (ZF) precoding solution that can null the received signal at the eavesdropper. We show that the ZF precoding leads to a low SKR in challenging scenarios of low transmit powers and small eavesdropping distances. To improve the SKR in these challenging scenarios, we propose a novel low-complexity machine learning-based beam focusing (MLBF) scheme. Simulation results show that the proposed MLBF scheme achieves a higher SKR than the benchmark methods.
Multi-Input, Multi-Output (MIMO) techniques are seeing widespread usage in wireless communication systems due to their large capacity gains. On the other hand, security is a concern of any wireless system, which can make schemes that implement physical layer security key in assuring secure communications. In this paper, we study the physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques. More concretely. the security potential against an unintended eavesdropper is analysed, and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higher the secrecy rate. In addition, in a scenario where there is Line of Sight (LOS) between all users, it is shown that the secrecy rate can be even higher than in the previous scenario. Therefore, MIMO-SVD schemes combined with SC-FDE can be an efficient option for highly secure MIMO communications.