no code implementations • 5 Nov 2024 • Ahmet M. Elbir, Abdulkadir Celik, Ahmed M. Eltawil
Therefore, this paper presents the design of Hybrid ANalog and Digital BeAmformers with Low resoLution (HANDBALL) digital-to-analog converters (DACs).
no code implementations • 21 Aug 2024 • Ahmet M. Elbir, Özlem Tuğfe Demir, Kumar Vijay Mishra, Symeon Chatzinotas, Martin Haardt
After nearly a century of specialized applications in optics, remote sensing, and acoustics, the near-field (NF) electromagnetic propagation zone is experiencing a resurgence in research interest.
no code implementations • 5 Jun 2024 • Ahmet M. Elbir, Kumar Vijay Mishra, Abdulkadir Celik, Ahmed M. Eltawil
Integrated sensing and communications (ISAC) has emerged as a means to efficiently utilize spectrum and thereby save cost and power.
no code implementations • 16 Jan 2024 • Ahmet M. Elbir, Abdulkadir Celik, Ahmed M. Eltawil, Moeness G. Amin
A joint design of both sensing and communication can lead to substantial enhancement for both subsystems in terms of size, cost as well as spectrum and hardware efficiency.
no code implementations • 7 Nov 2023 • Ahmet M. Elbir, Abdulkadir Celik, Ahmed M. Eltawil
Terahertz (THz) band is envisioned for the future sixth generation wireless systems thanks to its abundant bandwidth and very narrow beamwidth.
no code implementations • 25 Oct 2023 • Ahmet M. Elbir, Kumar Vijay Mishra, Symeon Chatzinotas
In this work, we examine near-field DoA estimation for THz automotive radar.
no code implementations • 25 Sep 2023 • Ahmet M. Elbir, Abdulkadir Celik, Ahmed M. Eltawil
Terahertz (THz) band communications and integrated sensing and communications (ISAC) are two main facets of the sixth generation wireless networks.
no code implementations • 6 Sep 2023 • Ahmet M. Elbir, Kumar Vijay Mishra, Symeon Chatzinotas
Terahertz (THz) band is currently envisioned as the key building block to achieving the future sixth generation (6G) wireless systems.
no code implementations • 8 Aug 2023 • Kumar Vijay Mishra, Ahmet M. Elbir, Koichi Ichige
In the past few years, deep learning (DL) techniques have been introduced for designing sparse arrays.
no code implementations • 14 Jul 2023 • Ahmet M. Elbir, Asmaa Abdallah, Abdulkadir Celik, Ahmed M. Eltawil
In this paper, we develop a sparse array architecture for THz-ISAC with hybrid beamforming to provide a cost-effective solution.
no code implementations • 22 Mar 2023 • Ahmet M. Elbir, Kumar Vijay Mishra, Asmaa Abdallah, Abdulkadir Celik, Ahmed M. Eltawil
Then, we propose to employ a family of hybrid beamforming techniques such as hybrid, SI, and subcarrier-dependent analog-only, and beam-split-aware beamformers.
no code implementations • 9 Feb 2023 • Ahmet M. Elbir, Wei Shi, Anastasios K. Papazafeiropoulos, Pandelis Kourtessis, Symeon Chatzinotas
Unlike prior works which mostly ignore the impact of near-field beam-split (NB) and consider either narrowband scenario or far-field models, this paper introduces both a model-based and a model-free techniques for wideband THz channel estimation in the presence of NB.
no code implementations • 5 Feb 2023 • Ahmet M. Elbir, Symeon Chatzinotas
Terahertz (THz)-band has been envisioned for the sixth generation wireless networks thanks to its ultra-wide bandwidth and very narrow beamwidth.
no code implementations • 3 Feb 2023 • Ahmet M. Elbir, Kumar Vijay Mishra, Symeon Chatzinotas
The sixth-generation networks envision the terahertz (THz) band as one of the key enabling technologies because of its ultrawide bandwidth.
no code implementations • 8 Nov 2022 • Ahmet M. Elbir, Kumar Vijay Mishra, Abdulkadir Çelik, Ahmed M. Eltawil
To efficiently utilize the wireless spectrum and save hardware costs, the fifth generation and beyond (B5G) wireless networks envisage integrated sensing and communications (ISAC) paradigms to jointly access the spectrum.
no code implementations • 3 Nov 2022 • Ahmet M. Elbir, Kumar Vijay Mishra, Sergiy A. Vorobyov, Robert W. Heath Jr
With the advances in multi-antenna technologies largely for radar and communications, there has been a great interest on beamformer design mostly relying on convex/nonconvex optimization.
no code implementations • 2 Nov 2022 • Kumar Vijay Mishra, Ahmet M. Elbir, Amir I. Zaghloul
Metasurfaces (MTSs) are increasingly emerging as enabling technologies to meet the demands for multi-functional, small form-factor, efficient, reconfigurable, tunable, and low-cost radio-frequency (RF) components because of their ability to manipulate waves in a sub-wavelength thickness through modified boundary conditions.
no code implementations • 24 Sep 2022 • Ahmet M. Elbir
However, the ultra-wide bandwidth in THz causes beam-split phenomenon due to the use of a single analog beamformer (AB).
no code implementations • 7 Aug 2022 • Ahmet M. Elbir, Wei Shi, Anastasios K. Papazafeiropoulos, Pandelis Kourtessis, Symeon Chatzinotas
For the demonstration of ultra-wideband bandwidth and pencil-beamforming, the terahertz (THz)-band has been envisioned as one of the key enabling technologies for the sixth generation networks.
no code implementations • 2 Aug 2022 • Ahmet M. Elbir, Kumar Vijay Mishra, Symeon Chatzinotas, Mehdi Bennis
The sixth generation (6G) wireless networks aim to achieve ultra-high data transmission rates, very low latency and enhanced energy-efficiency.
no code implementations • 13 Jul 2022 • Ahmet M. Elbir, Wei Shi, Kumar Vijay Mishra, Symeon Chatzinotas
This paper addresses two major challenges in terahertz (THz) channel estimation: the beam-split phenomenon, i. e., beam misalignment because of frequency-independent analog beamformers, and computational complexity because of the usage of ultra-massive number of antennas to compensate propagation losses.
no code implementations • 24 Jun 2022 • Ahmet M. Elbir, Wei Shi, Kumar Vijay Mishra, Anastasios K. Papazafeiropoulos, Symeon Chatzinotas
Without channel estimation, the proposed approach exhibits approximately 60% improvement in image and speech classification tasks for diverse scenarios such as millimeter wave and IEEE 802. 11p vehicular channels.
no code implementations • 6 May 2022 • Ahmet M. Elbir, Sinem Coleri, Kumar Vijay Mishra
Channel estimation is a critical task in intelligent reflecting surface (IRS)-assisted wireless systems due to the uncertainties imposed by environment dynamics and rapid changes in the IRS configuration.
no code implementations • 14 Apr 2022 • Ahmet M. Elbir, Kumar Vijay Mishra, M. R. Bhavani Shankar, Symeon Chatzinotas
The intelligent reflecting surface (IRS) alters the behavior of wireless media and, consequently, has potential to improve the performance and reliability of wireless systems such as communications and radar remote sensing.
no code implementations • 7 May 2021 • Ahmet M. Elbir, Sinem Coleri, Anastasios K. Papazafeiropoulos, Pandelis Kourtessis, Symeon Chatzinotas
To address this common scenario, we propose a more efficient approach called hybrid federated and centralized learning (HFCL), wherein only the clients with sufficient resources employ FL, while the remaining ones send their datasets to the PS, which computes the model on behalf of them.
no code implementations • 27 Feb 2021 • Ahmet M. Elbir, Kumar Vijay Mishra, Symeon Chatzinotas
Wireless communications and sensing at terahertz (THz) band are increasingly investigated as promising short-range technologies because of the availability of high operational bandwidth at THz.
no code implementations • 23 Feb 2021 • Ahmet M. Elbir, Anastasios K. Papazafeiropoulos, Symeon Chatzinotas
Model-free techniques, such as machine learning (ML), have recently attracted much interest towards the physical layer design, e. g., symbol detection, channel estimation, and beamforming.
no code implementations • 15 Feb 2021 • Ahmet M. Elbir, Sinem Coleri, Kumar Vijay Mishra
Then, we leverage federated learning (FL) with dropout learning (DL) to train a learning model on the local dataset of users, who estimate the beamformers by feeding the model with their channel data.
no code implementations • 13 Nov 2020 • Ahmet M. Elbir, Sinem Coleri, Kumar Vijay Mishra
We address this through a novel hybrid federated and centralized learning (HFCL) framework to effectively train a learning model by exploiting the computational capability of the clients.
no code implementations • 15 Oct 2020 • Ahmet M. Elbir, Gokhan Gurbilek, Burak Soner, Anastasios K. Papazafeiropoulos, Pandelis Kourtessis, Sinem Coleri
As a worldwide pandemic, the coronavirus disease-19 (COVID-19) has caused serious restrictions in people's social life, along with the loss of lives, the collapse of economies and the disruption of humanitarian aids.
no code implementations • 7 Oct 2020 • Ahmet M. Elbir, Kumar Vijay Mishra
We discuss DL design challenges from the perspective of data, learning, and transceiver architectures.
no code implementations • 5 Sep 2020 • Ahmet M. Elbir, Kumar Vijay Mishra
Data-driven techniques, such as deep learning (DL), are critical in addressing these challenges.
no code implementations • 25 Aug 2020 • Ahmet M. Elbir, Sinem Coleri
Channel estimation via ML requires model training on a dataset, which usually includes the received pilot signals as input and channel data as output.
no code implementations • 19 Jun 2020 • Ahmet M. Elbir
To reduce the complexity and provide robustness, in this work, we propose a deep learning (DL) framework to deal with both hybrid beamforming and channel estimation.
no code implementations • 2 Jun 2020 • Ahmet M. Elbir, Burak Soner, Sinem Coleri, Deniz Gunduz, Mehdi Bennis
Machine learning (ML) has recently been adopted in vehicular networks for applications such as autonomous driving, road safety prediction and vehicular object detection, due to its model-free characteristic, allowing adaptive fast response.
no code implementations • 20 May 2020 • Ahmet M. Elbir, Sinem Coleri
In this work, we introduce a federated learning (FL) based framework for hybrid beamforming, where the model training is performed at the BS by collecting only the gradients from the users.
no code implementations • 24 Apr 2020 • Ahmet M. Elbir, Kumar Vijay Mishra
Sparse sensor array selection arises in many engineering applications, where it is imperative to obtain maximum spatial resolution from a limited number of array elements.
1 code implementation • 29 Jan 2020 • Ahmet M. Elbir, A Papazafeiropoulos, P. Kourtessis, S. Chatzinotas
This letter presents the first work introducing a deep learning (DL) framework for channel estimation in large intelligent surface (LIS) assisted massive MIMO (multiple-input multiple-output) systems.
no code implementations • 20 Dec 2019 • Ahmet M. Elbir, Kumar Vijay Mishra, M. R. Bhavani Shankar, Björn Ottersten
Hybrid analog and digital beamforming transceivers are instrumental in addressing the challenge of expensive hardware and high training overheads in the next generation millimeter-wave (mm-Wave) massive MIMO (multiple-input multiple-output) systems.
1 code implementation • 9 Dec 2019 • Ahmet M. Elbir
This letter introduces a deep learning (DL) framework for direction-of-arrival (DOA) estimation.
1 code implementation • 1 Dec 2019 • Ahmet M. Elbir
The performance of the proposed method is evaluated with numerical simulations and it is shown that the proposed array geometries VCA and VNA can provide much less sensors as compared to the conventional coprime planar arrays.
no code implementations • 11 Nov 2019 • Ahmet M. Elbir, Anastasios Papazafeiropoulos
In fact, we design a convolutional neural network for MIMO (CNN-MIMO) that accepts as input an imperfect channel matrix and gives the analog precoder and combiners at the output.
no code implementations • 31 Oct 2019 • Ahmet M. Elbir, Kumar Vijay Mishra
In broadband millimeter-wave (mm-Wave) systems, it is desirable to design hybrid beamformers with common analog beamformer for the entire band while employing different baseband beamformers in different frequency sub-bands.
Signal Processing
no code implementations • 27 Feb 2018 • Ahmet M. Elbir, Kumar Vijay Mishra, Yonina C. Eldar
Direction of arrival (DoA) estimation of targets improves with the number of elements employed by a phased array radar antenna.