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On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity

We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all access points (APs) are connected in a linear-topolpgy fronthaul with constrained capacity and send a common message to a single receiver. By modeling the system as an extension of the multiple-access cha...

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Autores principales: Zhang, Peng, Willems, Frans M. J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7516895/
https://www.ncbi.nlm.nih.gov/pubmed/33286191
http://dx.doi.org/10.3390/e22040418
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author Zhang, Peng
Willems, Frans M. J.
author_facet Zhang, Peng
Willems, Frans M. J.
author_sort Zhang, Peng
collection PubMed
description We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all access points (APs) are connected in a linear-topolpgy fronthaul with constrained capacity and send a common message to a single receiver. By modeling the system as an extension of the multiple-access channel with partially cooperating encoders, we derive the channel capacity of the two-AP setting and then extend the results to arbitrary N-AP scenarios. By developing a cooperating mode concept, we investigate the optimal cooperation among the encoders (APs) when we limit the total fronthaul capacity, and the total transmit power is constrained as well. It is demonstrated that achieving capacity requires a water-pouring distribution of the total available fronthaul capacity over the fronthaul links. Our study reveals that a linear growth of total fronthaul capacity results in a logarithmic growth of the beamforming capacity. Moreover, even if the number of APs would be unlimited, only a finite number of them need to be activated. We found an expression for this number.
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spelling pubmed-75168952020-11-09 On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity Zhang, Peng Willems, Frans M. J. Entropy (Basel) Article We investigate the downlink of a cell-free massive multiple-in multiple-out system in which all access points (APs) are connected in a linear-topolpgy fronthaul with constrained capacity and send a common message to a single receiver. By modeling the system as an extension of the multiple-access channel with partially cooperating encoders, we derive the channel capacity of the two-AP setting and then extend the results to arbitrary N-AP scenarios. By developing a cooperating mode concept, we investigate the optimal cooperation among the encoders (APs) when we limit the total fronthaul capacity, and the total transmit power is constrained as well. It is demonstrated that achieving capacity requires a water-pouring distribution of the total available fronthaul capacity over the fronthaul links. Our study reveals that a linear growth of total fronthaul capacity results in a logarithmic growth of the beamforming capacity. Moreover, even if the number of APs would be unlimited, only a finite number of them need to be activated. We found an expression for this number. MDPI 2020-04-07 /pmc/articles/PMC7516895/ /pubmed/33286191 http://dx.doi.org/10.3390/e22040418 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Zhang, Peng
Willems, Frans M. J.
On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title_full On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title_fullStr On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title_full_unstemmed On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title_short On the Downlink Capacity of Cell-Free Massive MIMO with Constrained Fronthaul Capacity
title_sort on the downlink capacity of cell-free massive mimo with constrained fronthaul capacity
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7516895/
https://www.ncbi.nlm.nih.gov/pubmed/33286191
http://dx.doi.org/10.3390/e22040418
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