Article
Computer Science, Information Systems
Xinhua Wang, Julian Cheng, Chao Zhai, Alexei Ashikhmin
Summary: In this paper, a partial cooperative zero-forcing (PCZF) decoding scheme is proposed for the uplink cell-free massive MIMO system. Power control algorithms are introduced based on two criteria: maximizing the minimum achievable rate and maximizing the sum rate.
IEEE INTERNET OF THINGS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Trinh Van Chien, Hien Quoc Ngo, Symeon Chatzinotas, Bjorn Ottersten, Merouane Debbah
Summary: This paper investigates the uplink ergodic spectral efficiency (SE) of each user under the double scattering channel model. A closed-form expression of the uplink ergodic SE is derived by exploiting the maximum ratio combining technique based on imperfect channel state information. The asymptotic SE behaviors as a function of the number of antennas at each base station (BS) and the number of scatterers available at each radio channel are further studied.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Liutong Du, Lihua Li, Hien Quoc Ngo, Trang C. Mai, Michail Matthaiou
Summary: The proposed joint maximum-ratio and zero-forcing (JMRZF) precoding scheme in cell-free massive MIMO systems offers a balance between spectral efficiency and front-haul signaling overhead. AP subset selection based on large-scale fading coefficients is introduced, along with max-min power control to optimize system performance. This scheme outperforms local precoding methods and significantly improves spectral efficiency compared to uniform power control.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2021)
Article
Computer Science, Information Systems
Insang Yoo, David R. Smith
Summary: We propose an uplink massive MIMO system using holographic metasurfaces as a sector antenna operating at 3.5 GHz. The antenna consists of rectangular waveguide-fed metasurfaces combined into a planar aperture, each with subwavelength-sized metamaterial elements as radiators. The metasurfaces support multiple beams and achieve high spatial resolution in the azimuth directions, forming uncorrelated MIMO channels between the base station and users. The proposed metasurface antenna is structurally simple, low-cost, and efficient, suitable for addressing RF hardware issues in massive MIMO systems.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Murat Temiz, Emad Alsusa, Mohammed W. Baidas
Summary: This paper proposes a joint uplink massive MIMO communication and OFDM radar sensing architecture, achieving the separation and detection of radar returns and communication signals while considering self-interference.
IEEE TRANSACTIONS ON COGNITIVE COMMUNICATIONS AND NETWORKING
(2022)
Article
Engineering, Electrical & Electronic
Han Yu, Li You, Wenjin Wang, Xinping Yi
Summary: The approach proposed in the study utilizes an active channel sparsification strategy and weighted bipartite graph to simplify the user/beam selection problem, effectively addressing the challenges posed by multi-user channel spatial correlation.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Mamoun Guenach, Ali A. Gorji, Andre Bourdoux
Summary: This study proposes a point-to-multipoint fronthaul topology for scalable CF massive MIMO, providing a systematic user-centric solution. Experimental results show that power control alone is not enough to ensure the best objective, requiring appropriate user-AP association for improved system signal-to-noise ratio.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2021)
Article
Telecommunications
Chao Zhang, Aymen Askri, Ghaya Rekaya-Ben Othman, Li Wang
Summary: This letter proposes a dimensionality reduction scheme to mitigate the degradation induced by quantization noise in uplink cloud RANs. By transforming observations at radio heads to a reduced size and intensively using the quantization resource, the decoding performance can be enhanced, especially for low-fronthaul capacity links. Simulations confirm the superiority of the proposed scheme.
IEEE COMMUNICATIONS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Nhan Thanh Nguyen, Kyungchun Lee, Huaiyu Dai
Summary: This paper investigates hybrid analog-digital beamforming architectures for uplink cell-free millimeter-wave massive MIMO systems and proposes two HBF schemes, namely decentralized HBF (D-HBF) and semi-centralized HBF (SC-HBF). It is shown that the analog beamformers generated in these two schemes provide approximately the same achievable rates, despite the lower complexity and lack of CSI requirement of D-HBF. Furthermore, a novel adaptive RF chain-activation scheme is proposed to reduce power consumption while achieving significant improvement in energy efficiency.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Abhinav Anand, Chandra R. Murthy
Summary: This paper investigates the uplink performance of a multi-user MIMO-OFDM system with mobile users. It proposes a general subcarrier allocation scheme and derives expressions for the ICI power, signal to interference plus noise ratio, and achievable uplink sum-rate. The study shows that the system incurs a near-constant ICI power that depends linearly on the ratio of users per subcarrier to subcarriers per user, irrespective of power distribution across subcarriers by the user equipment (UE). Additionally, the paper exploits the coherence bandwidth of the channel to reduce pilot sequence length for uplink channel estimation.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2022)
Article
Telecommunications
Muhammad Farooq, Hien Quoc Ngo, Le Nam Tran
Summary: This article considers the problem of max-min fairness in the uplink cell-free massive MIMO system with per-user power constraints. A mirror prox algorithm-based method is proposed to solve the power control problem by reformulating it as a convex-concave problem. Simulation results confirm the optimality of the proposed solution and its higher efficiency compared to existing methods.
IEEE COMMUNICATIONS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Hong Wang, Chen Liu, Zheng Shi, Yaru Fu, Rongfang Song
Summary: The article explores how STBC technology can enhance the performance of two-cell MIMO-NOMA networks, involving joint detection techniques, power allocation, and beamforming design.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Ozgecan Ozdogan, Emil Bjornson
Summary: This paper focuses on a single-cell massive MIMO system with dual-polarized antennas at both ends. The study considers practical aspects of dual-polarization, such as cross-polar discrimination and cross-polar correlations. The analysis includes the derivation of achievable spectral efficiencies and proposes power-control algorithms for maximizing the sum spectral efficiencies in both uplink and downlink scenarios. The results show that dual-polarized systems achieve higher spectral efficiencies compared to uni-polarized setups, even under severe cross-polar conditions. Additionally, these systems benefit more from advanced signal processing techniques.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Yuto Hama, Hideki Ochiai
Summary: This paper proposes a new interference cancellation approach for coded uplink MIMO systems that support a massive number of IoT devices, by introducing MF-QIC to improve system error performance and spectral efficiency. Simulation results demonstrate that the proposed low-complexity polar-coded MF-QIC outperforms other conventional approaches even in the presence of imperfect channel state information.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Xuesong Cai, Istvan Z. Kovacs, Jeroen Wigard, Rafhael Amorim, Fredrik Tufvesson, Preben E. Mogensen
Summary: This paper focuses on the uplink communications of massive cellular-connected UAVs and proposes different power allocation algorithms to handle severe interference, effectively enhancing the uplink SEs.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Mahmoud Zaher, Ozlem Tugfe Demir, Emil Bjornson, Marina Petrova
Summary: This paper discusses a cell-free massive MIMO system with a large number of geographically distributed APs serving multiple users via coherent joint transmission. The downlink performance of the system is evaluated under two power allocation optimization objectives. The paper proposes centralized algorithms and trains a DNN to approximate the network-wide power allocation, providing higher SE using local information.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Emil Bjornson, Yonina C. Eldar, Erik G. Larsson, Angel Lozano, H. Vincent Poor
Summary: Wireless communication technology has made significant progress in the past 25 years, both in terms of societal adoption and technical sophistication. By 1998, mobile phones had become compact and affordable devices that could be widely used in developed and developing countries. The introduction of cellular networks and competition in the telecommunications market led to the popularity of mobile phones as fashion accessories with unique designs. This breakthrough technology allowed people to communicate with each other, rather than being limited to communicating with specific locations.
IEEE SIGNAL PROCESSING MAGAZINE
(2023)
Article
Engineering, Electrical & Electronic
Rodrigo Capobianco Guido, Tulay Adali, Emil Bjoernson, Laure Blanc-Feraud, Ulisses Braga-Neto, Behnaz Ghoraani, Christian Jutten, Alle-Jan Van der Veen, Hong Vicky Zhao, Xiaoxing Zhu
Summary: The IEEE Signal Processing Society has provided 75 years of service to the signal processing community, making significant contributions to technological advancement.
IEEE SIGNAL PROCESSING MAGAZINE
(2023)
Article
Engineering, Electrical & Electronic
Enyu Shi, Jing Zhang, Jiayi Zhang, Derrick Wing Kwan Ng, Bo Ai
Summary: Cell-free massive MIMO is a promising network that offers a significant improvement in achievable rate compared to conventional cellular massive MIMO systems. However, the commonly used Shannon-type achievable rate is not applicable for short-packet communication. In order to achieve ultra-reliable and low-latency communication in cell-free massive MIMO systems, we optimize the precoding vector at the access points to maximize the minimum user rate in both centralized and decentralized fashion.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Shuaifei Chen, Jiayi Zhang, Emil Bjornson, Bo Ai
Summary: This paper proposes an interference-aware massive access (IAMA) scheme for cell-free massive MIMO systems. It focuses on joint AP-UE association and pilot assignment to optimize user fairness and average spectral efficiency. The proposed scheme outperforms benchmark schemes in terms of these metrics.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Ozgecan Ozdogan, Emil Bjornson
Summary: This paper focuses on a single-cell massive MIMO system with dual-polarized antennas at both ends. The study considers practical aspects of dual-polarization, such as cross-polar discrimination and cross-polar correlations. The analysis includes the derivation of achievable spectral efficiencies and proposes power-control algorithms for maximizing the sum spectral efficiencies in both uplink and downlink scenarios. The results show that dual-polarized systems achieve higher spectral efficiencies compared to uni-polarized setups, even under severe cross-polar conditions. Additionally, these systems benefit more from advanced signal processing techniques.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Computer Science, Information Systems
Ema Becirovic, Emil Bjornson, Erik G. Larsson
Summary: Explored the improvement of detection performance in grant-free random access systems by utilizing the correlation of user activities. Showed that considerable performance gains can be achieved by adding regularizers, which consider the activity correlation, to the non-negative least squares algorithm.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Konstantinos Ntontin, Alexandros-Apostolos A. Boulogeorgos, Emil Bjornson, Wallace Alves Martins, Steven Kisseleff, Sergi Abadal, Eduard Alarcon, Anastasios Papazafeiropoulos, Fotis I. Lazarakis, Symeon Chatzinotas
Summary: In this paper, the feasibility of fully-energy-autonomous operation of reconfigurable intelligent surfaces (RIS) through wireless energy harvesting (EH) is examined. A suitable energy-consumption model is proposed, based on the integrated controller architecture, to identify the main RIS energy-consuming components and include the energy consumption needed for channel estimation. A novel RIS architecture is introduced, enabling EH through RIS unit-cell (UC) splitting. An EH policy is presented, where a subset of the UCs is used for beamsteering while the remaining UCs absorb energy. The results demonstrate the feasibility of the proposed architecture and the efficiency of the presented algorithms.
IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING
(2023)
Article
Engineering, Electrical & Electronic
Abhishek Maganbhai Sonagara, Mohit Mishra, Rakhesh Singh Kshetrimayum, Emil Bjornson, Zhi Ning Chen
Summary: This letter proposes a flexible and ultra-thin uniplanar end fire antenna that uses spoof surface plasmon polariton (SSPP). The antenna employs a single-metal layered groundless structure, which is an inherent advantage of SSPP. It includes a metallic strip for wideband radiation and C-shaped directors for directivity enhancement. The antenna is fabricated and measured on flat and curved surfaces, showing a low profile, small volume, and wideband operation.
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS
(2023)
Article
Computer Science, Information Systems
Giacomo Bacci, Luca Sanguinetti, Emil Bjornson
Summary: This letter presents experimental evidence that the classical far-field approximation underestimates the achievable spectral efficiency of multi-user MIMO communications in the 30-GHz bands and above, even at ranges beyond the Fraunhofer distance. For planar arrays with typical sizes, computing combining schemes based on the far-field model significantly reduces channel gain and spatial multiplexing capability. In contrast, using the radiative near-field model, interference rejection schemes, such as the optimal minimum mean-square-error combiner, appear to be very promising when combined with electrically large arrays to meet the requirements of next-generation networks.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Computer Science, Information Systems
Mahmoud Zaher, Emil Bjornson, Marina Petrova
Summary: The existence of unknown interference is a common issue in wireless communication networks, especially in multi-user MIMO networks. This paper proposes a Bayesian method for modeling the unknown interference power in the uplink of a cellular network. Numerical results demonstrate that our method accurately models the distribution of the unknown interference power and can be effectively used for rate adaptation with guaranteed target outage performance.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Konstantinos Ntontin, Emil Bjornson, Alexandros-Apostolos A. Boulogeorgos, Zaid Abdullah, Agapi Mesodiakaki, Sergi Abadal, Symeon Chatzinotas
Summary: In this work, the performance of time-splitting and unit cell-splitting protocols for reconfigurable intelligent surfaces (RISs) are compared analytically in terms of their ability to fulfill energy needs through wireless energy harvesting. Analytical solutions are provided for optimal resource allocation in both protocols under various fading distributions. The article also reveals trends in achievable rates relative to RIS energy consumption based on analysis. The numerical results validate the findings and show that the unit cell-splitting protocol achieves higher average rates, but at the cost of reduced signal-to-noise ratio as RIS energy demands increase.
IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING
(2023)
Article
Engineering, Electrical & Electronic
Guillem Femenias, Felip Riera-Palou, Emil Bjornson
Summary: Cell-free massive MIMO networks can solve interference issues in cellular networks, but guaranteeing scalability is a challenge. User-centric architectures can solve this problem, but the current best centralized combiner/precoder (P-MMSE) has limitations in scalability. This paper proposes an improved P-MMSE (IP-MMSE) scheme to address this issue.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2023)
Proceedings Paper
Telecommunications
Ozlem Tugfe Demir, Meysam Masoudi, Emil Bjornson, Cicek Cavdar
Summary: This paper proposes a new cell-free architecture based on V-CRAN for massive MIMO. The goal is to minimize power consumption by considering various factors, and the results show that cell-free massive MIMO can substantially improve the maximum rate with excellent energy efficiency.
IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC 2022)
(2022)
Proceedings Paper
Telecommunications
Anders Enqvist, Ozlem Tugfe Demir, Cicek Cavdar, Emil Bjornson
Summary: This paper examines the energy consumption of user equipment (UE) when transmitting finite-sized data packets and introduces a method to improve channel conditions using a reconfigurable intelligent surface (RIS). By adjusting the pilot overhead and subarray size, energy consumption can be minimized.
IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC 2022)
(2022)
