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In cell-free massive MIMO systems with multiple distributed access points (APs) serving multiple users over the same time-frequency resources, downlink beamforming is done through spatial precoding. Precoding vectors can be optimally…

Systems and Control · Electrical Eng. & Systems 2025-04-08 Mehdi Zafari , Divyanshu Pandey , Rahman Doost-Mohammady , César A. Uribe

This paper investigates a six-dimensional movable antenna (6DMA)-aided cell-free multi-user multiple-input multiple-output (MIMO) communication system. In this system, each distributed access point (AP) can flexibly adjust its array…

Signal Processing · Electrical Eng. & Systems 2026-01-09 Yichi Zhang , Yuchen Zhang , Wenyan Ma , Lipeng Zhu , Jianquan Wang , Wanbin Tang , Rui Zhang

We analyze the uplink performance of a distributed massive multiple-input multiple-output (MIMO) architecture in which the remotely located access points (APs) are connected to a central processing unit via a fiber-optical fronthaul…

Information Theory · Computer Science 2024-05-30 Anzhong Hu , Lise Aabel , Giuseppe Durisi , Sven Jacobsson , Mikael Coldrey , Christian Fager , Christoph Studer

The large beamforming gain used to operate at millimeter wave (mmWave) frequencies requires obtaining channel information to configure hybrid antenna arrays. Previously proposed wideband channel estimation strategies, however, assume…

Signal Processing · Electrical Eng. & Systems 2019-06-06 Javier Rodriguez-Fernandez , Nuria Gonzalez-Prelcic

Distributed massive MIMO networks are envisioned to realize cooperative multi-point transmission in next-generation wireless systems. For efficient cooperative hybrid beamforming, the cluster of access points (APs) needs to obtain precise…

Information Theory · Computer Science 2023-08-31 Nariman Torkzaban , Amir Khojastepour , John S. Baras

Over-the-air computation (AirComp) has been recognized as a low-latency solution for wireless sensor data fusion, where multiple sensors send their measurement signals to a receiver simultaneously for computation. Most existing work only…

Information Theory · Computer Science 2024-10-28 Tianrui Qin , Wanchun Liu , Branka Vucetic , Yonghui Li

A Cell-Free Massive MIMO (multiple-input multiple-output) system comprises a very large number of distributed access points (APs)which simultaneously serve a much smaller number of users over the same time/frequency resources based on…

Information Theory · Computer Science 2017-01-18 Hien Quoc Ngo , Alexei Ashikhmin , Hong Yang , Erik G. Larsson , Thomas L. Marzetta

In this paper, we explore cooperative sensing and communication within cell-free integrated sensing and communication (ISAC) systems. Specifically, multiple transmit access points (APs) collaboratively serve multiple communication users…

Signal Processing · Electrical Eng. & Systems 2025-02-17 Rang Liu , Ming Li , Qian Liu

Over-the-air computation (AirComp) is considered as a communication-efficient solution for data aggregation and distributed learning by exploiting the superposition properties of wireless multi-access channels. However, AirComp is…

Signal Processing · Electrical Eng. & Systems 2024-09-04 Chen Chen , Emil Björnson , Carlo Fischione

Synchronization is a fundamental procedure in cellular systems whereby an UE acquires the time and frequency information required to decode the data transmitted by a BS. Due to the necessity of using large antenna arrays to obtain the…

Signal Processing · Electrical Eng. & Systems 2020-05-05 Javier Rodriguez-Fernandez

High throughput satellites employing multibeam antennas and full frequency reuse for broadband satellite services are considered in this paper. Such architectures offer, for example, a cost-effective solution to optimize data delivery and…

Signal Processing · Electrical Eng. & Systems 2019-02-08 Robert T. Schwarz , Thomas Delamotte , Kai-Uwe Storek , Andreas Knopp

In this paper we consider a time-division duplex cell-free massive multiple-input multiple-output (MIMO) system where many distributed access points (APs) simultaneously serve many users. A normalized conjugate beamforming scheme, which…

Information Theory · Computer Science 2019-09-10 Giovanni Interdonato , Hien Quoc Ngo , Erik G. Larsson , Pål Frenger

In what ways could cellular massive MIMO be improved? This technology has already been shown to bring huge performance gains. However, coverage holes and difficulties to transmit multiple streams to multi-antenna users because of…

Signal Processing · Electrical Eng. & Systems 2025-01-08 Sara Willhammar , Hiroki Iimori , Joao Vieira , Lars Sundström , Fredrik Tufvesson , Erik G. Larsson

Synchronization of transceiver chains is a major challenge in the practical realization of massive MIMO and especially distributed massive MIMO. While frequency synchronization is comparatively easy to achieve, estimating the carrier phase…

Signal Processing · Electrical Eng. & Systems 2022-12-23 Florian Euchner , Phillip Stephan , Marc Gauger , Stephan ten Brink

We investigate distributed multiple-input multiple-output (D-MIMO) integrated sensing and communication (ISAC) systems, in which multiple phase-synchronized access points (APs) jointly serve user equipments (UEs) while cooperatively…

Signal Processing · Electrical Eng. & Systems 2025-12-29 Venkatesh Tentu , Henk Wymeersch , Musa Furkan Keskin , Sauradeep Dey , Tommy Svensson

In future Internet-of-Things networks, sensors or even access points can be mounted on ground/aerial vehicles for smart-city surveillance or environment monitoring. To support the high-mobility sensing with low network latency, a technique…

Information Theory · Computer Science 2018-07-13 Guangxu Zhu , Kaibin Huang

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

In this letter, we propose a six-dimensional movable antenna (6DMA)-aided cell-free massive multiple-input multiple-output (MIMO) system to fully exploit its macro spatial diversity, where a set of distributed access points (APs), each…

Information Theory · Computer Science 2024-12-03 Xiaoming Shi , Xiaodan Shao , Beixiong Zheng , Rui Zhang

Large-scale multiple-input and multiple-output (MIMO) systems are capable of achieving high date rate. However, given the high hardware cost and excessive power consumption of massive MIMO systems, as a remedy, intelligent metasurfaces have…

Information Theory · Computer Science 2024-05-17 Qingchao Li , Mohammed El-Hajjar , Chao Xu , Jiancheng An , Chau Yuen , Lajos Hanzo

This paper investigates pilot assignment and access point (AP) selection strategies for uplink cell-free massive multiple-input multiple-output (CF-mMIMO) systems. We propose channel similarity-aware pilot assignment (CAPA) and AP selection…

Signal Processing · Electrical Eng. & Systems 2026-02-24 Saeed Mohammadzadeh , Kanapathippillai Cumanan , Pei Liu , Hien Quoc Ngo