A Survey on Physical Layer Security in Near-Field Communication

XU Yongjun; LI Jing; LUO Dongxin; WANG Ji; LI Xingwang; YANG Long; CHEN Li

doi:10.11999/JEIT250336

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XU Yongjun, LI Jing, LUO Dongxin, WANG Ji, LI Xingwang, YANG Long, CHEN Li. A Survey on Physical Layer Security in Near-Field Communication[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250336

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XU Yongjun, LI Jing, LUO Dongxin, WANG Ji, LI Xingwang, YANG Long, CHEN Li. A Survey on Physical Layer Security in Near-Field Communication[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT250336

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A Survey on Physical Layer Security in Near-Field Communication

doi: 10.11999/JEIT250336 cstr: 32379.14.JEIT250336

XU Yongjun^{1, 2},
LI Jing¹,
LUO Dongxin¹,
WANG Ji^{3
,
,},
LI Xingwang⁴,
YANG Long⁵,
CHEN Li¹

1.
School of Communications and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
2.
State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
3.
College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
4.
School of Physics and Electronic Information Engineering, Henan Polytechnic University, Jiaozuo 454003, China
5.
School of Communication Engineering, Xidian University, Xi’an 710000, China

Funds: National Natural Science Foundation of China (62271094), Natural Science Foundation of Chongqing (CSTB2022NSCQ-LZX0009, CSTB2023NSCQLZX0079), New Chongqing Youth Innovative Talent Program (CSTB2024NSCQ-QCXMX0059), Key Research and Development Program of Hubei Province under Grant (2023BAB061), Fundamental Research Funds for the Central Universities of China under grant (CCNU25ai026), Open Research Fund of State Key Laboratory of Millimeter Waves, Southeast University (KN202502-07)

Rev Recd Date: 2025-09-17

Available Online: 2025-09-23

Abstract

Abstract

Significance Traditional wireless communication systems have relied on far-field plane-wave models to support wide-area coverage and long-distance transmission. However, emerging Sixth-Generation (6G) applications—such as extended reality, holographic communication, pervasive intelligence, and smart factories—demand ultra-high bandwidth, ultra-low latency, and sub-centimeter-level localization accuracy. These requirements exceed the spatial multiplexing gains and interference suppression achievable under far-field assumptions. Enabled by extremely large-scale antenna arrays and terahertz technologies, the near-field region has expanded to hundreds of meters, where spherical-wave propagation enables precise beam focusing and flexible spatial resource management. The additional degrees of freedom in the angle and distance domains, however, give rise to new Physical Layer Security (PLS) challenges, including joint angle–distance eavesdropping, beam-split-induced information leakage caused by frequency-dependent focusing, and security–interference conflicts in hybrid near- and far-field environments. This paper provides a comprehensive survey of near-field PLS techniques, advancing theoretical understanding of spherical-wave propagation and associated threat models while offering guidance for designing robust security countermeasures and informing the development of future 6G security standards. Progress This paper presents a comprehensive survey of recent advances in PLS for near-field communications in 6G networks, with an in-depth discussion of key enabling technologies and optimization methodologies. Core security techniques, including beam focusing, Artificial Noise (AN), and multi-technology integration, are first examined in terms of their security objectives. Beam focusing exploits ultra-large-scale antenna arrays and the spherical-wave propagation characteristics of near-field communication to achieve precise spatial confinement, thereby reducing information leakage. AN introduces deliberately crafted noise toward undesired directions to hinder eavesdropping. Multi-technology integration combines terahertz communications, Reconfigurable Intelligent Surfaces (RIS), and Integrated Sensing And Communication (ISAC), markedly enhancing overall security performance. Tailored strategies are then analyzed for different transmission environments, including Line-of-Sight (LoS), Non-Line-of-Sight (NLoS), and hybrid near–far-field conditions. In LoS scenarios, beamforming optimization strengthens interference suppression. In NLoS scenarios, RIS reconstructs transmission links, complicating unauthorized reception. For hybrid near–far-field environments, multi-beam symbol-level precoding spatially distinguishes users and optimizes beamforming patterns, ensuring robust security for mixed-distance user groups. Finally, critical challenges are highlighted, including complex channel modeling, tradeoffs between security and performance, and interference management in converged multi-network environments. Promising directions for future research are also identified, such as Artificial Intelligence (AI)-assisted security enhancement, cooperative multi-technology schemes, and energy-efficient secure communications in near-field systems. Conclusions This paper provides a comprehensive survey of PLS techniques for near-field communications, with particular emphasis on enabling technologies and diverse transmission scenarios. The fundamentals and system architecture of near-field communications are first reviewed, highlighting their distinctions from far-field systems and their unique channel characteristics. Representative PLS approaches are then examined, including beam focusing, AN injection, and multi-technology integration with RIS and ISAC. Secure transmission strategies are further discussed for LoS, NLoS, and hybrid near–far-field environments. Finally, several open challenges are identified, such as accurate modeling of complex channels, balancing security and performance, and managing interference in multi-network integration. Promising research directions are also outlined, including hybrid near–far-field design and AI-enabled security. These directions are expected to provide theoretical foundations for advancing and standardizing near-field communication security in future 6G networks. Prospects Research on PLS for near-field communications remains at an early stage, with no unified or systematic framework established to date. As communication scenarios become increasingly diverse and complex, future studies should prioritize hybrid far-field and near-field environments, where channel coupling and user heterogeneity raise new security challenges. AI-driven PLS techniques show strong potential for adaptive optimization and improved resilience against adversarial threats. In parallel, integrating near-field PLS with advanced technologies such as RIS and ISAC can deliver joint improvements in security, efficiency, and functionality. Moreover, low-power design will be essential to balance security performance with energy efficiency, enabling the development of high-performance, intelligent, and sustainable near-field secure communication systems.
- Near-field communication,
- Physical Layer Security (PLS),
- 6G,
- Beam focusing

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References(65)

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