Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection

This paper analyzes visibility region (VR) detection and spectral efficiency (SE) in a reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) system, with a focus on hybrid near-field (NF) and far-field (FF) communication. A statistical channel mod...

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Main Authors: Xiangjun Ma, Ali Arshad Nasir, Daniel Benevides Da Costa
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Open Journal of the Communications Society
Subjects:
Online Access:https://ieeexplore.ieee.org/document/10891689/
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author Xiangjun Ma
Ali Arshad Nasir
Daniel Benevides Da Costa
author_facet Xiangjun Ma
Ali Arshad Nasir
Daniel Benevides Da Costa
author_sort Xiangjun Ma
collection DOAJ
description This paper analyzes visibility region (VR) detection and spectral efficiency (SE) in a reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) system, with a focus on hybrid near-field (NF) and far-field (FF) communication. A statistical channel model is introduced, leveraging the Fresnel approximation and Rayleigh distance concepts. To enable VR detection using signals received from the radio-frequency (RF) chains of the RIS, a novel detection matrix based on the Welch-bound-equality (WBE) codebook is proposed. Its performance is thoroughly analyzed, with closed-form expressions derived for the probabilities of missed detection and false alarm. Based on the estimated VRs, a generalized expression for the estimated aggregated channel from the user equipment (UE) to the access point (AP) is derived using the linear minimum mean-squared-error (LMMSE) estimator, which supports SE analysis. To mitigate pilot contamination during VR detection and channel state information (CSI) estimation, a novel two-stage pilot assignment scheme is proposed. In the VR detection stage, orthogonal pilots are assigned to NF-UEs while FF-UEs remain silent, enhancing detection accuracy. In the CSI estimation stage, UE-AP cooperation is integrated with pilot assignment and power control, delivering superior SE performance compared to the group-based scheme.
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spelling doaj-art-1b04ee4da62c4ac3a7bcb4ab5bf31e882025-08-20T03:18:09ZengIEEEIEEE Open Journal of the Communications Society2644-125X2025-01-0161710172610.1109/OJCOMS.2025.354339310891689Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region DetectionXiangjun Ma0https://orcid.org/0000-0002-6104-4563Ali Arshad Nasir1https://orcid.org/0000-0001-5012-1562Daniel Benevides Da Costa2https://orcid.org/0000-0002-5439-7475Department of Electrical Engineering, Interdisciplinary Research Center for Communication Systems and Sensing, King Fahd University of Petroleum and Minerals, Dhahran, Saudi ArabiaDepartment of Electrical Engineering, Interdisciplinary Research Center for Communication Systems and Sensing, King Fahd University of Petroleum and Minerals, Dhahran, Saudi ArabiaDepartment of Electrical Engineering, Interdisciplinary Research Center for Communication Systems and Sensing, King Fahd University of Petroleum and Minerals, Dhahran, Saudi ArabiaThis paper analyzes visibility region (VR) detection and spectral efficiency (SE) in a reconfigurable intelligent surface (RIS)-aided cell-free massive multiple-input multiple-output (CF-mMIMO) system, with a focus on hybrid near-field (NF) and far-field (FF) communication. A statistical channel model is introduced, leveraging the Fresnel approximation and Rayleigh distance concepts. To enable VR detection using signals received from the radio-frequency (RF) chains of the RIS, a novel detection matrix based on the Welch-bound-equality (WBE) codebook is proposed. Its performance is thoroughly analyzed, with closed-form expressions derived for the probabilities of missed detection and false alarm. Based on the estimated VRs, a generalized expression for the estimated aggregated channel from the user equipment (UE) to the access point (AP) is derived using the linear minimum mean-squared-error (LMMSE) estimator, which supports SE analysis. To mitigate pilot contamination during VR detection and channel state information (CSI) estimation, a novel two-stage pilot assignment scheme is proposed. In the VR detection stage, orthogonal pilots are assigned to NF-UEs while FF-UEs remain silent, enhancing detection accuracy. In the CSI estimation stage, UE-AP cooperation is integrated with pilot assignment and power control, delivering superior SE performance compared to the group-based scheme.https://ieeexplore.ieee.org/document/10891689/Hybrid near/far-fieldCF-mMIMORISvisibility region
spellingShingle Xiangjun Ma
Ali Arshad Nasir
Daniel Benevides Da Costa
Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
IEEE Open Journal of the Communications Society
Hybrid near/far-field
CF-mMIMO
RIS
visibility region
title Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
title_full Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
title_fullStr Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
title_full_unstemmed Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
title_short Hybrid Near/Far-Field Communications of RIS-Aided Cell-Free Massive MIMO With Visibility Region Detection
title_sort hybrid near far field communications of ris aided cell free massive mimo with visibility region detection
topic Hybrid near/far-field
CF-mMIMO
RIS
visibility region
url https://ieeexplore.ieee.org/document/10891689/
work_keys_str_mv AT xiangjunma hybridnearfarfieldcommunicationsofrisaidedcellfreemassivemimowithvisibilityregiondetection
AT aliarshadnasir hybridnearfarfieldcommunicationsofrisaidedcellfreemassivemimowithvisibilityregiondetection
AT danielbenevidesdacosta hybridnearfarfieldcommunicationsofrisaidedcellfreemassivemimowithvisibilityregiondetection