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The spatial degrees of freedom (DoFs) greatly increase in the near-field region of millimeter wave or terahertz multiple-input multiple-output communications with extremely large antenna arrays (XL-MIMO). To employ the increased spatial…

Information Theory · Computer Science 2023-05-18 Shuaishuai Guo , Kaiqian Qu

The degrees-of-freedom (DoF) of the multi-antenna three-way channel (3WC) with an intermittent node is studied. Special attention is given to the impact of adaptation. A nonadaptive transmission scheme based on interference alignment,…

Information Theory · Computer Science 2017-01-30 Anas Chaaban , Aydin Sezgin , Mohamed-Slim Alouini

The degrees of freedom (DoF) region of the 2-user multiple-antenna or MIMO (multiple-input, multiple-output) interference channel (IC) is studied under fast fading and the assumption of {\em delayed} channel state information (CSI) wherein…

Information Theory · Computer Science 2015-03-18 Chinmay S. Vaze , Mahesh K. Varanasi

This paper considers a deterministic physical model of massive multiple-input multiple-output (MIMO) systems with uniform linear antenna arrays. It is known that the maximum spatial degrees of freedom is achieved by spacing antenna elements…

Information Theory · Computer Science 2016-01-22 Keigo Takeuchi

Holographic multiple-input multiple-output (MIMO) has emerged as a key enabler for 6G networks, yet conventional planar implementations suffer from spatial correlation and mutual coupling at sub-wavelength spacing, which fundamentally limit…

Signal Processing · Electrical Eng. & Systems 2026-04-30 Quan Gao , Shuai S. A. Yuan , Zhanwen Wang , Wanchen Yang , Chongwen Huang , Xiaoming Chen , Wei E. I. Sha

We consider a line-of-sight communication link between two holographic surfaces (HoloSs), and provide a closed-form expression for the effective degrees of freedom (eDoF), i.e., the number of orthogonal communication modes that can be…

Information Theory · Computer Science 2025-06-17 Juan Carlos Ruiz-Sicilia , Marco Di Renzo , Marco Donald Migliore , Merouane Debbah , H. Vincent Poor

Holographic MIMO refers to a (possibly large) array with a large number of individually controlled and densely deployed antennas. The objective of this paper is to provide further insight into the use of closely spaced antennas in the…

Information Theory · Computer Science 2024-03-20 Antonio Alberto D'Amico , Luca Sanguinetti

Two major areas of modern radio astronomy, namely, explosive astrophysical transient phenomena and observations of cosmological structures, are driving the design of aperture arrays towards large numbers of low-cost elements consisting of…

Instrumentation and Methods for Astrophysics · Physics 2025-01-15 Nithyanandan Thyagarajan

Powered by position-flexible antennas, the emerging fluid antenna system (FAS) technology is postulated as a key enabler for massive connectivity in 6G networks. The free movement of antenna elements enables the opportunistic minimization…

Signal Processing · Electrical Eng. & Systems 2024-07-24 Pablo Ramirez-Espinosa , David Morales-Jimenez , Kai-Kit Wong

Modern MIMO communication systems are almost exclusively designed under the assumption of locally plane wavefronts over antenna arrays. This is known as the far-field approximation and is soundly justified at sub-6-GHz frequencies at most…

Information Theory · Computer Science 2023-02-28 Giacomo Bacci , Luca Sanguinetti , Emil Björnson

Flexible antenna arrays (FAAs) can physically reshape their geometry to add new spatial degrees of freedom, whereas transmit beamforming adjusts the complex element weights to electronically steer and shape the array's radiation pattern,…

Signal Processing · Electrical Eng. & Systems 2026-03-02 Zhen Xu , Gaojie Chen , Jing Zhu , Weiwei Zhao , Yonghui Li , Rahim Tafazolli , Wei Huang

This work explores how degrees of freedom (DoF) results from wireless networks can be translated into capacity results for their finite field counterparts that arise in network coding applications. The main insight is that scalar (SISO)…

Information Theory · Computer Science 2013-04-30 Sundar R. Krishnamurthy , Syed A. Jafar

The $K\times 2$ and $2\times K$, Multiple-Input Multiple-Output (MIMO) X channel with constant channel coefficients available at all transmitters and receivers is considered. A new alignment scheme, named \emph{layered interference…

Information Theory · Computer Science 2014-12-24 Seyyed Hassan Mahboubi , Mumtaz Hussain , Abolfazl Seyed Motahari , Amir Keyvan Khandani

Extremely large-scale multiple-input multiple-output (XL-MIMO) communications, enabled by numerous antenna elements integrated into large antenna surfaces, can provide increased effective degree of freedom (EDoF) to achieve high diversity…

Information Theory · Computer Science 2024-12-25 Shaohua Yue , Liang Liu , Boya Di

Holographic multiple-input multiple-output (MIMO) is envisioned as one of the most promising technology enablers for future sixth-generation (6G) networks. The use of electrically large holographic surface (HoloS) antennas has the potential…

Information Theory · Computer Science 2025-06-17 Juan Carlos Ruiz-Sicilia , Marco Di Renzo , Placido Mursia , Vincenzo Sciancalepore , Merouane Debbah

Holographic multiple-input multiple-output (HMIMO) technology, which uses spatially continuous surfaces for signal transmission and reception, is envisioned to be a promising solution for improving the data rate and coverage of wireless…

Information Theory · Computer Science 2023-05-26 Jiancheng An , Chau Yuen , Chongwen Huang , Merouane Debbah , H. Vincent Poor , Lajos Hanzo

This paper presents a generalized closed-form beamforming technique that can achieve the maximum degrees of freedom in compounded multiple-input multiple-output (MIMO) broadcast channels with mixed classes of multiple-antenna users. The…

Information Theory · Computer Science 2020-04-27 Galymzhan Nauryzbayev , Emad Alsusa , Mohamed Abdallah

With the evolution of mobile communication systems toward large-scale arrays, high-frequency operation, and reconfigurable antenna architectures, fluid antenna systems (FAS) operating in the near-field (NF) regime provide new degrees of…

Information Theory · Computer Science 2026-05-12 Peng Zhang , Jian Dang , Miaowen Wen , Ziyang Liu , Chen Zhao , Huaifeng Shi , Chengsheng Pan , Zaichen Zhang

Space-fed large antenna arrays offer superior efficiency, simplicity, and reductions in size, weight, power, and cost (SWaP-C) compared to constrained-feed systems. Historically, horn antennas have been used for space feeding, but they…

Signal Processing · Electrical Eng. & Systems 2025-05-15 Krishan Kumar Tiwari , Thomas Flisgen , Wolfgang Heinrich , Giuseppe Caire

The generalized degrees of freedom (GDoF) region of the MIMO Gaussian interference channel (IC) is obtained for the general case of an arbitrary number of antennas at each node and where the signal-to-noise ratios (SNR) and…

Information Theory · Computer Science 2011-03-15 Sanjay Karmakar , Mahesh K. Varanasi