How to Differentiate between Near Field and Far Field: Revisiting the Rayleigh Distance

Fuente: arXiv
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Autori principali: Sun, Shu, Li, Renwang, Han, Chong, Liu, Xingchen, Xue, Liuxun, Tao, Meixia
Natura: Preprint
Pubblicazione: 2023
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author Sun, Shu
Li, Renwang
Han, Chong
Liu, Xingchen
Xue, Liuxun
Tao, Meixia
author_facet Sun, Shu
Li, Renwang
Han, Chong
Liu, Xingchen
Xue, Liuxun
Tao, Meixia
contents Future wireless systems are likely to adopt extremely large aperture arrays to achieve higher throughput, wider coverage, and higher spatial resolution. Conventional wireless systems predominantly operate in the far field (FF) of the radiation source. However, as the array size increases and the carrier wavelength decreases, the near field (NF) becomes nonnegligible. Since the NF and FF differ in many aspects, it is critical to identify their corresponding regions. In this article, we first provide a comprehensive overview of the existing NF-FF boundaries, then introduce a novel NF-FF demarcation method based on effective degrees of freedom (EDoF) of the channel. Since EDoF is intimately related to channel capacity, the EDoF-based border is able to characterize key channel performance more accurately than the classic Rayleigh distance and other representative benchmarks. Furthermore, we analyze the main features of the EDoF-based NF-FF boundary, provide insights into system design, and outline the associated challenges and research opportunities.
format Preprint
id arxiv_https___arxiv_org_abs_2309_13238
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle How to Differentiate between Near Field and Far Field: Revisiting the Rayleigh Distance
Sun, Shu
Li, Renwang
Han, Chong
Liu, Xingchen
Xue, Liuxun
Tao, Meixia
Signal Processing
Future wireless systems are likely to adopt extremely large aperture arrays to achieve higher throughput, wider coverage, and higher spatial resolution. Conventional wireless systems predominantly operate in the far field (FF) of the radiation source. However, as the array size increases and the carrier wavelength decreases, the near field (NF) becomes nonnegligible. Since the NF and FF differ in many aspects, it is critical to identify their corresponding regions. In this article, we first provide a comprehensive overview of the existing NF-FF boundaries, then introduce a novel NF-FF demarcation method based on effective degrees of freedom (EDoF) of the channel. Since EDoF is intimately related to channel capacity, the EDoF-based border is able to characterize key channel performance more accurately than the classic Rayleigh distance and other representative benchmarks. Furthermore, we analyze the main features of the EDoF-based NF-FF boundary, provide insights into system design, and outline the associated challenges and research opportunities.
title How to Differentiate between Near Field and Far Field: Revisiting the Rayleigh Distance
topic Signal Processing
url https://arxiv.org/abs/2309.13238