963 citations · 4.2k across the 63 of their papers we have counts for
28 papers · 1 filter
Movable Antenna Arrays with Imperfect Channel State Information in Rich Scattering Environments
Yizhen Zhao, Amna Irshad, Emil Bjornson
The growing demand for high spectral efficiency in 6G and beyond has driven research into adaptive antenna architectures capable of exploiting the spatial structure of multipath pr…
Unexpected Far-Near-Far Transition in Mobile Near Field Terahertz Communications
Peng Zhang, Hanmei Yuan, Zhe Wang +2
At THz frequencies, the radiative near-field distance can be sufficiently large to matter in real deployments. Existing near-field formulas are often understood in a simple way: as…
Reciprocal Beyond Diagonal Reconfigurable Intelligent Surface: Distributed Scattering Matrix Design and MIMO Beamforming via Fractional Programming and Manifold Optimization
Iván Alexander Morales Sandoval, Marko Fidanovski, Hyeon Seok Rou +2
We consider the optimization of beyond diagonal reconfigurable intelligent surface (BD-RIS)-aided multi-user (MU) cell-free (CF)-massive multiple-input multiple-output (mMIMO) syst…
Pilot-Free Predictive Multi-User Beamforming via Sensing Management in Cell-Free Networks
Eren Berk Kama, Murat Babek Salman, Isaac Skog +1
This paper presents a sensing management frame- work for integrated sensing and communications (ISAC) within cell-free massive multiple-input multiple-output (MIMO) systems to redu…
User Mobility Demands Near-Field Communications in Terahertz Band Wireless Networks Beyond 6G
Peng Zhang, Vitaly Petrov, Arjun Singh +2
Near-field propagation is often unavoidable at terahertz (THz) frequencies due to the large apertures needed for sufficient array gain, yet near-field operation complicates practic…
Symbol-Level Mask-Compliant Hybrid Precoding for Multi-User MIMO-OFDM Systems
Navid Reyhanian, Parisa Ramezani, Emil Björnson
Millimeter-wave (mmWave) technology is a crucial enabler for next-generation networks because it offers substantially greater available bandwidth. mmWave multiple-input multiple-ou…
Unlocking the Energy-Saving Potential in O-RAN Cell-Free Massive MIMO by Joint Orchestration of Radio, Wireless Fronthaul, and Cloud Resources
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Network virtualization and cloudification in Open Radio Access Networks (O-RAN) enable joint orchestration of the processing and fronthaul resources, which are essential for realiz…
Cramer-Rao Bound Analysis of Bistatic ISAC Under Partial Symbol Knowledge and Clutter
Steven Rivetti, Gabor Fodor, Emil Bjornson +1
Integrated sensing and communication (ISAC) systems rely on communication waveforms to perform sensing tasks, thus making their sensing performance strongly dependent on the level…
Performance Evaluation of Movable Antenna Arrays in Wideband Multi-User MIMO Systems
Amna Irshad, Emil Björnson, Alva Kosasih +1
Future wireless networks are expected to support increasingly high data rates and user densities, motivating advanced multi-antenna architectures capable of adapting to dynamic pro…
Physics-Informed Spatial-Temporal Transformer for Terahertz Near-Field Beam Tracking
Zhi Zeng, Chong Han, Emil Björnson
Terahertz (THz) ultra-massive multiple-input multiple-output (UM-MIMO) promises ultra-high throughput, while its highly directional beams demand rapid and accurate beam tracking dr…
Airy Beam Engineering in Near-field Communications: A Tractable Closed-Form Analysis in the Terahertz Band
Wenqi Zhao, Chong Han, Emil Björnson
Terahertz (THz) communication can offer terabit-per-second rates in future wireless systems, thanks to the ultra-wide bandwidths, but require large antenna arrays. As antenna apert…
Joint and Streamwise Distributed MIMO Satellite Communications with Multi-Antenna Ground Users
Parisa Ramezani, Emil Björnson
We consider a low Earth orbit downlink communication, where multiple satellites jointly serve multi-antenna ground users, transmitting multiple spatial streams per user. Using a li…
On the Impact of Channel Aging and Doppler-Affected Clutter on OFDM ISAC Systems
Steven Rivetti, Gabor Fodor, Emil Björnson +1
The temporal evolution of the propagation environment plays a central role in integrated sensing and communication (ISAC) systems. A slow-time evolution manifests as channel aging…
Flexible Continuous Aperture Arrays
Kuranage Roche Rayan Ranasinghe, Zhaolin Wang, Giuseppe Thadeu Freitas de Abreu +1
A novel electromagnetic (EM) structure termed flexible continuous aperture array (FCAPA) is proposed, which incorporates inherent surface flexibility into typical continuous apertu…
Precoding for Uplink RIS-Assisted Cell-Free MIMO-OFDM Systems with Hardware Impairments
Navid Reyhanian, Reza Ghaderi Zefreh, Parisa Ramezani +1
This paper studies a reconfigurable intelligent surface (RIS)-assisted cell-free massive multiple-input multiple-output (CF-mMIMO) system with multiple RISs. Joint design of transm…
Joint Spatial and Spectral Hybrid Precoding for Multi-User MIMO-OFDM Systems
Navid Reyhanian, Reza Ghaderi Zefreh, Parisa Ramezani +1
Millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems operate over wide bandwidths and frequency-selective channels, making orthogonal frequency-division multiplex…
Multi-Task Over-the-Air Federated Learning in Cell-Free Massive MIMO Systems
Chen Chen, Emil Björnson, Carlo Fischione
Wireless devices are expected to provide a wide range of AI services in 6G networks. The increasing computing capabilities of wireless devices and the surge of wireless data motiva…
Energy-Efficient Cell-Free Massive MIMO with Wireless Fronthaul
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Cell-free massive MIMO improves the fairness among the user equipments (UEs) in the network by distributing many cooperating access points (APs) around the region while connecting…
Localization in Massive MIMO Networks: From Near-Field to Far-Field
Parisa Ramezani, Özlem Tuğfe Demir, Emil Björnson
Source localization is the process of estimating the location of signal sources based on the signals received at different antennas of an antenna array. It has diverse applications…
Energy Harvesting Maximization for Reconfigurable Intelligent Surfaces Using Amplitude Measurements
Morteza Tavana, Meysam Masoudi, Emil Björnson
Energy harvesting can enable a reconfigurable intelligent surface (RIS) to self-sustain its operations without relying on external power sources. In this paper, we consider the pro…
Amplitude-Based Sequential Optimization of Energy Harvesting with Reconfigurable Intelligent Surfaces
Morteza Tavana, Meysam Masoudi, Emil Björnson
Reconfigurable Intelligent Surfaces (RISs) have gained immense popularity in recent years because of their ability to improve wireless coverage and their flexibility to adapt to th…
Impact of Pilot Contamination Between Operators With Interfering Reconfigurable Intelligent Surfaces
Doğa Gürgünoğlu, Emil Björnson, Gábor Fodor
In this paper, we study the impact of pilot contamination in a system where two operators serve their respective users with the assistance of two wide-band reconfigurable intellige…
Cell-Free Massive MIMO in O-RAN: Energy-Aware Joint Orchestration of Cloud, Fronthaul, and Radio Resources
Özlem Tuğfe Demir, Meysam Masoudi, Emil Björnson +1
For the energy-efficient deployment of cell-free massive MIMO functionality in a practical wireless network, the end-to-end (from radio site to the cloud) energy-aware operation is…
Cell-Free Massive MIMO in Virtualized CRAN: How to Minimize the Total Network Power?
Özlem Tuğfe Demir, Meysam Masoudi, Emil Björnson +1
Previous works on cell-free massive MIMO mostly consider physical-layer and fronthaul transport aspects. How to deploy cell-free massive MIMO functionality in a practical wireless…