239 citations · 551 across the 25 of their papers we have counts for
26 papers
Simultaneous Direct and Indirect Channel Estimation for RIS-Assisted MIMO Communications
Daniel V. C. de Oliveira, Daniel C. Alcantara, Fazal. E Asim +2
This paper introduces an enhanced channel estimation method for reconfigurable intelligent surface (RIS)-assisted multiple-input multiple-output (MIMO) communications. Considering…
Tensor Methods for Language Models: From Token Representation to Training, Adaptation, Inference, Compression, and Interpretability
Matvei Tarasov, Salman Ahmadi-Asl, Andre L. F. de Almeida +1
Large language models (LLMs) are built from structured high-dimensional objects such as token representations, weights, adaptation updates, caches, and activations, whose multiline…
Deconstructing the Composite Channel for Beyond Diagonal RIS: Channel Estimation and Beamforming Design
Fazal-E Asim, André L. F. de Almeida, Bruno Sokal +2
As beyond-diagonal reconfigurable intelligent surfaces (BD-RISs) gain increasing attention in high-frequency wireless communications, accurate and scalable channel-estimation metho…
Joint Channel and Symbol Estimation for RIS-Assisted Fluid Antenna Systems
Josué V. de Araújo, Daniel C. Alcantara, Gilderlan T. de Araújo +1
This paper addresses joint channel and symbol estimation in reconfigurable intelligent surface (RIS)-aided multiuser uplink systems with fluid antennas (FAs) at the base station. W…
Channel Estimation for Movable Intelligent Surface
Daniel C. Alcantara, Josué V. de Araújo, Gilderlan T. de Araújo +1
This paper proposes a tensor-based channel estimation framework for an uplink MIMO system assisted by a movable intelligent surface. The considered architecture combines a fixed tr…
Channel Estimation for Flexible Intelligent Metasurface Aided MIMO Communications
Vinícius L. Romano, André L. F. de Almeida, Daniel C. Araújo
Flexible Intelligent Metasurfaces (FIMs) enable wireless systems to adapt their three-dimensional geometry through morphing, thereby providing new spatial degrees of freedom. Howev…
PARAFAC-Based Time-Varying Channel Estimation for IRS-Aided Communications
Kenneth B. A. Benício, André L. F. de Almeida, Bruno Sokal +3
This paper proposes a tensor-based parametric channel estimation technique for IRS-assisted communication systems with time-varying channel parameters. We exploit the multidimensio…
Channel Estimation for Beyond Diagonal RIS Exploiting Core Tensor Sparsity
Daniel Costa Araújo, André L. F. de Almeida
Beyond diagonal reconfigurable intelligent surfaces (BD-RISs) enhance wave manipulation through inter-element couplings but pose significant channel estimation challenges due to ca…
Randomized block Krylov method for approximation of truncated tensor SVD
Malihe Nobakht Kooshkghazi, Salman Ahmadi-Asl, Andre L. F. de Almeida
This paper is devoted to studying the application of the block Krylov subspace method for approximation of the truncated tensor SVD (T-SVD). The theoretical results of the proposed…
Reducing Complexity of Data-Aided Channel Estimation in RIS-Assisted Communications
Amarilton Lopes Magalhães, André Lima Férrer de Almeida, Gilderlan Tavares de Araújo
We consider the data-aided channel estimation (CE) problem in a reconfigurable intelligent surface (RIS)-assisted wireless communication system, where the channel and information s…
Joint Downlink-Uplink Channel Estimation for Non-Reciprocal RIS-Assisted Communications
Paulo R. B. Gomes, Amarilton L. Magalhães, André L. F. de Almeida
Reconfigurable intelligent surface (RIS) is a recent low-cost and energy-efficient technology with potential applicability for future wireless communications. Performance gains ach…
Tensor-Based Receivers for the Bistatic Sensing and Communication Scenario
Walter da C. Freitas, Gerard Favier, Andre L. F. de Almeida
We propose receivers for bistatic sensing and communication that exploit a tensor modeling of the received signals. We consider a hybrid scenario where the sensing link knows the t…
A Decoupled Channel Estimation Method for Beyond Diagonal RIS
Bruno Sokal, Fazal-E-Asim, André L. F. de Almeida +2
Beyond diagonal reconfigurable intelligent surface (BD-RIS) is a new architecture for RIS where elements are interconnected to provide more wave manipulation flexibility than tradi…
Semi-Blind Receivers for Hybrid Reflecting and Sensing RIS
Amarilton L. Magalhães, André L. F. de Almeida
Recent research has delved into advanced designs for reconfigurable intelligent surfaces (RIS) with integrated sensing functions. One promising concept is the hybrid RIS (HRIS), wh…
Efficient numerical frameworks for modelling ultrasonic beams propagating across interfaces
André Lello de Almeida, Melody Png, Bo Lan
Two different frameworks are developed to model the wave field generated by a transducer and propagating through one or more interfaces, and a Quasi-Monte Carlo (QMC) integration s…
Frustrated total internal reflection of ultrasonic waves at a fluid-coupled elastic plate
André Lello de Almeida, Ming Huang, Peiyao Huang +2
A complete treatment regarding frustrated total internal reflection (FTIR) of ultrasonic waves is presented and validated against experiments, providing a theoretical explanation f…
Channel Estimation for Intelligent Reflecting Surface Assisted MIMO Systems: A Tensor Modeling Approach
Gilderlan T. de Araújo, André L. F. de Almeida, Rémy Boyer
Intelligent reflecting surface (IRS) is an emerging technology for future wireless communications including 5G and especially 6G. It consists of a large 2D array of (semi-)passive…
Channel Parameter Estimation for Millimeter-Wave Cellular Systems with Hybrid Beamforming
Fazal-E-Asim, Felix Antreich, Charles C. Cavalcante +2
To achieve high data rates defined in 5G, the use of millimeter-waves and massive-MIMO are indispensable. To benefit from these technologies, an accurate estimation of the channel…
Rank-one Detector for Kronecker-Structured Constant Modulus Constellations
Fazal-E-Asim, André L. F. de Almeida, Martin Haardt +2
To achieve a reliable communication with short data blocks, we propose a novel decoding strategy for Kronecker-structured constant modulus signals that provides low bit error ratio…
Low-Rank Tensor MMSE Equalization
Lucas N. Ribeiro, André L. F. de Almeida, João C. M. Mota
New-generation wireless communication systems will employ large-scale antenna arrays to satisfy the increasing capacity demand. This massive scenario brings new challenges to the c…
Double-Sided Massive MIMO Transceivers for MmWave Communications
Lucas N. Ribeiro, Stefan Schwarz, André L. F. de Almeida
We propose practical transceiver structures for double-sided massive multiple-input-multiple-output (MIMO) systems. Unlike standard massive MIMO, both transmit and receive sides ar…
Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs
Lucas N. Ribeiro, Stefan Schwarz, Markus Rupp +1
With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce…
Joint Channel Estimation / Data Detection in MIMO-FBMC/OQAM Systems - A Tensor-Based Approach
Eleftherios Kofidis, Christos Chatzichristos, Andre L. F. de Almeida
Filter bank-based multicarrier (FBMC) systems are currently being considered as a prevalent candidate for replacing the long established cyclic prefix (CP)-based orthogonal frequen…
Rank-1 Tensor Approximation Methods and Application to Deflation
Alex Pereira da Silva, Pierre Comon, Andre Lima Ferrer de Almeida
Because of the attractiveness of the canonical polyadic (CP) tensor decomposition in various applications, several algorithms have been designed to compute it, but efficient ones a…