Dynamic Precoding for Near-Field Secure Communications: Implementation and Performance Analysis

Fuente: arXiv
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Main Authors: Teng, Zihao, An, Jiancheng, Masouros, Christos, Li, Hongbin, Gan, Lu, Ng, Derrick Wing Kwan
Format: Preprint
Published: 2025
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author Teng, Zihao
An, Jiancheng
Masouros, Christos
Li, Hongbin
Gan, Lu
Ng, Derrick Wing Kwan
author_facet Teng, Zihao
An, Jiancheng
Masouros, Christos
Li, Hongbin
Gan, Lu
Ng, Derrick Wing Kwan
contents The increase in antenna apertures and transmission frequencies in next-generation wireless networks is catalyzing advancements in near-field communications (NFC). In this paper, we investigate secure transmission in near-field multi-user multiple-input single-output (MU-MISO) scenarios. Specifically, with the advent of extremely large-scale antenna arrays (ELAA) applied in the NFC regime, the spatial degrees of freedom in the channel matrix are significantly enhanced. This creates an expanded null space that can be exploited for designing secure communication schemes. Motivated by this observation, we propose a near-field dynamic hybrid beamforming architecture incorporating artificial noise, which effectively disrupts eavesdroppers at any undesired positions, even in the absence of their channel state information (CSI). Furthermore, we comprehensively analyze the dynamic precoder's performance in terms of the average signal-to-interference-plus-noise ratio, achievable rate, secrecy capacity, secrecy outage probability, and the size of the secrecy zone. In contrast to far-field secure transmission techniques that only enhance security in the angular dimension, the proposed algorithm exploits the unique properties of spherical wave characteristics in NFC to achieve secure transmission in both the angular and distance dimensions. Remarkably, the proposed algorithm is applicable to arbitrary modulation types and array configurations. Numerical results demonstrate that the proposed method achieves approximately 20\% higher rate capacity compared to zero-forcing and the weighted minimum mean squared error precoders.
format Preprint
id arxiv_https___arxiv_org_abs_2505_04968
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dynamic Precoding for Near-Field Secure Communications: Implementation and Performance Analysis
Teng, Zihao
An, Jiancheng
Masouros, Christos
Li, Hongbin
Gan, Lu
Ng, Derrick Wing Kwan
Information Theory
Signal Processing
The increase in antenna apertures and transmission frequencies in next-generation wireless networks is catalyzing advancements in near-field communications (NFC). In this paper, we investigate secure transmission in near-field multi-user multiple-input single-output (MU-MISO) scenarios. Specifically, with the advent of extremely large-scale antenna arrays (ELAA) applied in the NFC regime, the spatial degrees of freedom in the channel matrix are significantly enhanced. This creates an expanded null space that can be exploited for designing secure communication schemes. Motivated by this observation, we propose a near-field dynamic hybrid beamforming architecture incorporating artificial noise, which effectively disrupts eavesdroppers at any undesired positions, even in the absence of their channel state information (CSI). Furthermore, we comprehensively analyze the dynamic precoder's performance in terms of the average signal-to-interference-plus-noise ratio, achievable rate, secrecy capacity, secrecy outage probability, and the size of the secrecy zone. In contrast to far-field secure transmission techniques that only enhance security in the angular dimension, the proposed algorithm exploits the unique properties of spherical wave characteristics in NFC to achieve secure transmission in both the angular and distance dimensions. Remarkably, the proposed algorithm is applicable to arbitrary modulation types and array configurations. Numerical results demonstrate that the proposed method achieves approximately 20\% higher rate capacity compared to zero-forcing and the weighted minimum mean squared error precoders.
title Dynamic Precoding for Near-Field Secure Communications: Implementation and Performance Analysis
topic Information Theory
Signal Processing
url https://arxiv.org/abs/2505.04968