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Towards Optimal Energy Efficiency in Cell-Free Massive MIMO Systems

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Towards Optimal Energy Efficiency in Cell-Free Massive MIMO Systems. / Papazafeiropoulos, A.; Ngo, H. Q.; Kourtessis, P.; Chatzinotas, S.; Senior, J. M.

In: IEEE Transactions on Green Communications and Networking, 12.02.2021.

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@article{77a222d03eb04fa3bddba026bb14f6fa,
title = "Towards Optimal Energy Efficiency in Cell-Free Massive MIMO Systems",
abstract = "Motivated by the ever-growing demand for green wireless communications and the advantages of cell-free (CF) massive multiple-input multiple-output (mMIMO) systems, we focus on the design of their downlink (DL) for optimal energy efficiency (EE). To address this fundamental topic, we assume that each access point (AP) is deployed with multiple antennas and serves multiple users on the same time-frequency resource while the APs are Poisson point process (PPP) distributed, which approaches realistically their opportunistic spatial randomness. Relied on tools from stochastic geometry, we derive a lower bound on the DL average achievable spectral efficiency (SE). Next, we consider a realistic power consumption model for CF mMIMO systems. These steps enable the formulation of a tractable optimization problem concerning the DL EE, which results in the analytical determination of the optimal pilot reuse factor, the AP density, and the number of AP antennas and users that maximize the EE. Hence, we provide useful design guidelines for CF mMIMO systems relating to fundamental system variables towards optimal EE. Among the results, we observe that an optimal pilot reuse factor and AP density exist, while larger values result in an increase of the interference, and subsequently, lower EE. Overall, it is shown that the CF mMIMO technology is a promising candidate for next-generation networks achieving simultaneously high SE and EE.",
keywords = "beyond 5G MIMO., Cell-free massive MIMO systems, energy efficiency, small cells networks, stochastic geometry",
author = "A. Papazafeiropoulos and Ngo, {H. Q.} and P. Kourtessis and S. Chatzinotas and Senior, {J. M.}",
note = "{\textcopyright} 2021 IEEE - This is the accepted manuscript version of an article which has been published in final form at https://dx.doi.org/10.1109/TGCN.2021.3059206 ",
year = "2021",
month = feb,
day = "12",
doi = "10.1109/TGCN.2021.3059206",
language = "English",
journal = "IEEE Transactions on Green Communications and Networking",
issn = "2473-2400",
publisher = "Institute of Electrical and Electronics Engineers Inc.",

}

RIS

TY - JOUR

T1 - Towards Optimal Energy Efficiency in Cell-Free Massive MIMO Systems

AU - Papazafeiropoulos, A.

AU - Ngo, H. Q.

AU - Kourtessis, P.

AU - Chatzinotas, S.

AU - Senior, J. M.

N1 - © 2021 IEEE - This is the accepted manuscript version of an article which has been published in final form at https://dx.doi.org/10.1109/TGCN.2021.3059206

PY - 2021/2/12

Y1 - 2021/2/12

N2 - Motivated by the ever-growing demand for green wireless communications and the advantages of cell-free (CF) massive multiple-input multiple-output (mMIMO) systems, we focus on the design of their downlink (DL) for optimal energy efficiency (EE). To address this fundamental topic, we assume that each access point (AP) is deployed with multiple antennas and serves multiple users on the same time-frequency resource while the APs are Poisson point process (PPP) distributed, which approaches realistically their opportunistic spatial randomness. Relied on tools from stochastic geometry, we derive a lower bound on the DL average achievable spectral efficiency (SE). Next, we consider a realistic power consumption model for CF mMIMO systems. These steps enable the formulation of a tractable optimization problem concerning the DL EE, which results in the analytical determination of the optimal pilot reuse factor, the AP density, and the number of AP antennas and users that maximize the EE. Hence, we provide useful design guidelines for CF mMIMO systems relating to fundamental system variables towards optimal EE. Among the results, we observe that an optimal pilot reuse factor and AP density exist, while larger values result in an increase of the interference, and subsequently, lower EE. Overall, it is shown that the CF mMIMO technology is a promising candidate for next-generation networks achieving simultaneously high SE and EE.

AB - Motivated by the ever-growing demand for green wireless communications and the advantages of cell-free (CF) massive multiple-input multiple-output (mMIMO) systems, we focus on the design of their downlink (DL) for optimal energy efficiency (EE). To address this fundamental topic, we assume that each access point (AP) is deployed with multiple antennas and serves multiple users on the same time-frequency resource while the APs are Poisson point process (PPP) distributed, which approaches realistically their opportunistic spatial randomness. Relied on tools from stochastic geometry, we derive a lower bound on the DL average achievable spectral efficiency (SE). Next, we consider a realistic power consumption model for CF mMIMO systems. These steps enable the formulation of a tractable optimization problem concerning the DL EE, which results in the analytical determination of the optimal pilot reuse factor, the AP density, and the number of AP antennas and users that maximize the EE. Hence, we provide useful design guidelines for CF mMIMO systems relating to fundamental system variables towards optimal EE. Among the results, we observe that an optimal pilot reuse factor and AP density exist, while larger values result in an increase of the interference, and subsequently, lower EE. Overall, it is shown that the CF mMIMO technology is a promising candidate for next-generation networks achieving simultaneously high SE and EE.

KW - beyond 5G MIMO.

KW - Cell-free massive MIMO systems

KW - energy efficiency

KW - small cells networks

KW - stochastic geometry

UR - http://www.scopus.com/inward/record.url?scp=85100844743&partnerID=8YFLogxK

U2 - 10.1109/TGCN.2021.3059206

DO - 10.1109/TGCN.2021.3059206

M3 - Article

AN - SCOPUS:85100844743

JO - IEEE Transactions on Green Communications and Networking

JF - IEEE Transactions on Green Communications and Networking

SN - 2473-2400

ER -