RIS and cell-free massive MIMO: a marriage for harsh propagation environments

Trinh Van Chien, Hien Quoc Ngo, Symeon Chatzinotas, Marco Di Renzo, Bjorn Ottersten

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


This paper considers Cell-Free Massive Multiple Input Multiple Output (MIMO) systems with the assistance of an RIS for enhancing the system performance. Distributed maximum-ratio combining (MRC) is considered at the access points (APs). We introduce an aggregated channel estimation method that provides sufficient information for data processing. The considered system is studied by using asymptotic analysis which lets the number of APs and/or the number of RIS elements grow large. A lower bound for the channel capacity is obtained for a finite number of APs and engineered scattering elements of the RIS, and closed-form expression for the uplink ergodic net throughput is formulated. In addition, a simple scheme for controlling the configuration of the RIS scattering elements is proposed. Numerical results verify the effectiveness of the proposed system design and the benefits of using RISs in Cell-Free Massive MIMO systems are quantified.

Original languageEnglish
Title of host publication2021 IEEE Global Communications Conference, GLOBECOM 2021 - Proceedings
PublisherInstitute of Electrical and Electronics Engineers Inc.
ISBN (Electronic)9781728181042
ISBN (Print)9781728181059
Publication statusPublished - 02 Feb 2022
Event2021 IEEE Global Communications Conference, GLOBECOM 2021 - Madrid, Spain
Duration: 07 Dec 202111 Dec 2021

Publication series

Name IEEE Global Communications Conference, GLOBECOM- Proceedings
ISSN (Print)1930-529X


Conference2021 IEEE Global Communications Conference, GLOBECOM 2021

Bibliographical note

Funding Information:
This work of T. V. Chien, S. Chatzinotas, and B. Ottersten was supported by RISOTTI - Reconfigurable Intelligent Surfaces for Smart Cities under project FNR/C20/IS/14773976/RISOTTI. The work of H. Q. Ngo was supported by the UK Research and Innovation Future Leaders Fellowships under Grant MR/S017666/1. The work of M. Di Renzo was supported in part by the European Commission through the H2020 ARIADNE project under grant agreement number 871464 and through the H2020 RISE-6G project under grant agreement number 101017011. The long version of this paper was submitted to the IEEE Trans. Wireless Comm. [1].

Publisher Copyright:
© 2021 IEEE.

ASJC Scopus subject areas

  • Artificial Intelligence
  • Computer Networks and Communications
  • Computer Science Applications
  • Hardware and Architecture
  • Information Systems and Management
  • Safety, Risk, Reliability and Quality
  • Health Informatics


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