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In a cell-free massive MIMO architecture a very large number of distributed access points simultaneously and jointly serves a much smaller number of mobile stations; a variant of the cell-free technique is the user-centric approach, wherein…

Signal Processing · Electrical Eng. & Systems 2019-03-28 Mario Alonzo , Stefano Buzzi , Alessio Zappone , Ciro D'Elia

In cell-free massive multiple-input multiple-output (MIMO) systems, the beamforming strategies at the base stations (BSs) and user equipments (UEs) can be computed building on bi-directional training. However, the precoding/decoding…

Signal Processing · Electrical Eng. & Systems 2021-10-13 Bikshapathi Gouda , Italo Atzeni , Antti Tölli

In cell-free massive multiple-input multiple-output systems, downlink power control is essential to ensure uniformly high service quality across users. Existing methods range from centralized iterative approaches requiring global channel…

Signal Processing · Electrical Eng. & Systems 2026-05-27 Giovanni Di Gennaro , Amedeo Buonanno , Gianmarco Romano , Francesco Verde , Stefano Buzzi , Francesco A. N. Palmieri

We consider a cell-free massive MIMO system with multiple antennas on the users and access points. In previous works, the downlink spectral efficiency (SE) has been evaluated using the hardening bound that requires no downlink pilots. This…

Signal Processing · Electrical Eng. & Systems 2024-04-30 Eren Berk Kama , Junbeom Kim , Emil Björnson

This paper investigates Cell-Free massive MIMO networks, where each access point (AP) is equipped with a hybrid transceiver, reducing the complexity and cost compared to a fully digital transceiver. Asymptotic approximations for the…

Information Theory · Computer Science 2023-01-16 Carles Diaz-Vilor , Alexei Ashikhmin , Hong Yang

Cell-free massive multiple-input multiple-output (mMIMO) offers significant advantages in mobility scenarios, mainly due to the elimination of cell boundaries and strong macro diversity. In this paper, we examine the downlink performance of…

Information Theory · Computer Science 2024-12-04 Ziheng Liu , Jiayi Zhang , Yiyang Zhu , Enyu Shi , Bo Ai

We consider a massive MU-MIMO downlink time-division duplex system where a base station (BS) equipped with many antennas serves several single-antenna users in the same time-frequency resource. We assume that the BS uses linear precoding…

Information Theory · Computer Science 2013-10-08 Hien Quoc Ngo , Erik G. Larsson , Thomas L. Marzetta

This paper focuses on the use of a deep learning approach to perform sum-rate-max and max-min power allocation in the uplink of a cell-free massive MIMO network. In particular, we train a deep neural network in order to learn the mapping…

Information Theory · Computer Science 2019-08-30 Carmen D'Andrea , Alessio Zappone , Stefano Buzzi , Merouane Debbah

This paper considers cell-free massive multiple-input multiple-output systems where the multiple-antenna access points (APs) assist the single-antenna user equipments (UEs) by wireless power transfer. The UEs utilize the energy harvested in…

Information Theory · Computer Science 2020-01-28 Özlem Tuğfe Demir , Emil Björnson

We consider the cell-free massive multiple-input multiple-output (MIMO) downlink, where a very large number of distributed multiple-antenna access points (APs) serve many single-antenna users in the same time-frequency resource. A simple…

Information Theory · Computer Science 2017-11-27 Hien Quoc Ngo , Le-Nam Tran , Trung Q. Duong , Michail Matthaiou , Erik G. Larsson

A large-scale distributed antenna system that serves the users by coherent joint transmission is called Cell-free Massive MIMO (multiple input multiple output). For a given user set, only a subset of the access points (APs) is likely needed…

Information Theory · Computer Science 2019-11-27 Trinh Van Chien , Emil Björnson , Erik G. Larsson

Millimeter-wave (mmWave) cell-free massive multi-user (MU) multiple-input multiple-output (MIMO) systems combine the large bandwidths available at mmWave frequencies with the improved coverage of cell-free systems. However, to combat the…

Information Theory · Computer Science 2022-07-21 Jannik Brun , Victoria Palhares , Gian Marti , Christoph Studer

We study support for unmanned aerial vehicle (UAV) communications through a cell-free massive MIMO architecture, wherein a large number of access points (APs) is deployed in place of large co-located massive MIMO arrays. We consider also a…

Information Theory · Computer Science 2020-01-13 Carmen D'Andrea , Adrian Garcia-Rodriguez , Giovanni Geraci , Lorenzo Galati Giordano , Stefano Buzzi

Cell-free massive multiple-input multiple-output is a potential candidate for future networks with pervasive connectivity by utilizing coherent joint transmission and distributed antenna arrays. This paper studies the exploitation of…

Signal Processing · Electrical Eng. & Systems 2026-04-14 Trinh Van Chien , Bui Trong Duc , Mohammadali Mohammadi , Hien Quoc Ngo , Michail Matthaiou

This paper considers wireless uplink information and downlink power transfer in cell-free massive multiple-input multiple-output systems. The single-antenna user equipments (UEs) utilize the energy harvested in the downlink to transmit…

Information Theory · Computer Science 2020-11-13 Özlem Tuğfe Demir , Emil Björnson

We consider the downlink of a multi-cell system with multi-antenna base stations and single-antenna user terminals, arbitrary base station cooperation clusters, distance-dependent propagation pathloss, and general "fairness" requirements.…

Information Theory · Computer Science 2016-11-18 Hoon Huh , Antonia M. Tulino , Giuseppe Caire

We study downlink channel estimation in a multi-cell Massive multiple-input multiple-output (MIMO) system operating in time-division duplex. The users must know their effective channel gains to decode their received downlink data. Previous…

Information Theory · Computer Science 2021-11-30 Amin Ghazanfari , Trinh Van Chien , Emil Björnson , Erik G. Larsson

This paper investigates the optimization of the long-standing probabilistically robust transmit beamforming problem with channel uncertainties in the multiuser multiple-input single-output (MISO) downlink transmission. This problem poses…

Information Theory · Computer Science 2024-06-06 Kai Liang , Gan Zheng , Zan Li , Kai-Kit Wong , Chan-Byoung Chae

We consider the downlink of a cooperative cellular communications system, where several base-stations around each mobile cooperate and perform zero-forcing to reduce the received interference at the mobile. We derive closed-form expressions…

Information Theory · Computer Science 2023-09-26 Itsik Bergel , Siddhartan Govindasamy

In this paper, we study the performance of the downlink of a cellular network with automatic repeat-request (ARQ) and a half duplex decode-and-forward shared relay. In this system, two multiple-input-multiple-output (MIMO) base stations…

Information Theory · Computer Science 2016-10-12 Ahmed Raafat Hosny , Ramy Abdallah Tannious , Amr El-Keyi