no code implementations • 6 Jul 2024 • Li You, Yongxiang Zhu, Xiaoyu Qiang, Christos G. Tsinos, Wenjin Wang, Xiqi Gao, Björn Ottersten
The next sixth generation (6G) networks are envisioned to integrate sensing and communications in a single system, thus greatly improving spectrum utilization and reducing hardware costs.
no code implementations • 26 Mar 2024 • Asad Mahmood, Thang X. Vu, Symeon Chatzinotas, Björn Ottersten
This work investigates the application of Beyond Diagonal Intelligent Reflective Surface (BD-IRS) to enhance THz downlink communication systems, operating in a hybrid: reflective and transmissive mode, to simultaneously provide services to indoor and outdoor users.
no code implementations • 13 Nov 2023 • Asad Mahmood, Thang X. Vu, Wali Ullah Khan, Symeon Chatzinotas, Björn Ottersten
We propose a joint optimization strategy to reduce system's worst-case latency and UAV hovering time by optimizing BD-IRS-UAV deployment and resource allocation.
no code implementations • 21 Sep 2023 • Wali Ullah Khan, Eva Lagunas, Zain Ali, Asad Mahmood, Chandan Kumar Sheemar, Manzoor Ahmed, Symeon Chatzinotas, Björn Ottersten
Backscatter communication (BC) technology offers sustainable solutions for next-generation Internet-of-Things (IoT) networks, where devices can transmit data by reflecting and adjusting incident radio frequency signals.
no code implementations • 6 Sep 2023 • Wali Ullah Khan, Asad Mahmood, Chandan Kumar Sheemar, Eva Lagunas, Symeon Chatzinotas, Björn Ottersten
This paper studies the potential of RIS-integrated NTNs to revolutionize the next-generation connectivity.
no code implementations • 29 Jul 2023 • Wali Ullah Khan, Eva Lagunas, Asad Mahmood, Zain Ali, Symeon Chatzinotas, Björn Ottersten
The objective is to maximize the sum rate of NOMA D2D communications by simultaneously optimizing the power budget of D2D transmitter, NOMA power allocation coefficients of D2D receivers and passive beamforming of RIS while guaranteeing the quality of services of UAV user.
no code implementations • 10 Jul 2023 • Juan Carlos Merlano Duncan, Vu Nguyen Ha, Jevgenij Krivochiza, Rakesh Palisetty, Geoffrey Eappen, Juan Andres Vasquez, Wallace Alves Martins, Symeon Chatzinotas, Björn Ottersten
The space communications industry is challenged to develop a technology that can deliver broadband services to user terminals equipped with miniature antennas, such as handheld devices.
no code implementations • 17 Jun 2023 • Wali Ullah Khan, Eva Lagunas, Asad Mahmood, Symeon Chatzinotas, Björn Ottersten
Then, in step 2, given the transmit power, we design passive beamforming for RIS by solving the semi-definite programming.
no code implementations • 8 May 2023 • Asad Mahmood, Thang X. Vu, Symeon Chatzinotas, Björn Ottersten
The main aim of this work is to derive an efficient technique for the allocation of radio resources, $3$D placement of UAVs, and user association matrices.
no code implementations • 25 Apr 2023 • Asad Mahmood, Thang X. Vu, Shree Krishna Sharma, Symeon Chatzinotas, Björn Ottersten
The main aim of this work is to derive the optimal allocation of radio resources, 3D placement of UAVs, and user association matrices.
no code implementations • 9 Mar 2023 • Wali Ullah Khan, Eva Lagunas, Asad Mahmood, Symeon Chatzinotas, Björn Ottersten
The proposed framework simultaneously optimizes the transmit power of ground terminals at LEO satellite and passive beamforming at RIS while ensuring the quality of services.
no code implementations • 2 Oct 2022 • Wali Ullah Khan, Asad Mahmood, Arash Bozorgchenani, Muhammad Ali Jamshed, Ali Ranjha, Eva Lagunas, Haris Pervaiz, Symeon Chatzinotas, Björn Ottersten, Petar Popovski
This paper first describes the introduction of 6G-empowered V2X communications and IRS technology.
no code implementations • 10 Sep 2022 • Ziyang Cheng, Linlong Wu, Bowen Wang, Bhavani Shankar, Bin Liao, Björn Ottersten
As a promising technology in beyond-5G (B5G) and 6G, dual-function radar-communication (DFRC) aims to ensure both radar sensing and communication on a single integrated platform with unified signaling schemes.
no code implementations • 4 Aug 2022 • Wali Ullah Khan, Zain Ali, Eva Lagunas, Symeon Chatzinotas, Björn Ottersten
We also propose two suboptimal schemes with fixed power allocation and random subcarrier beam assignment as the benchmark.
no code implementations • 24 Jun 2022 • Mirza Golam Kibria, Hayder Al-Hraishawi, Eva Lagunas, Symeon Chatzinotas, Björn Ottersten
Beam hopping (BH) and carrier aggregation (CA) are two promising technologies for the next generation satellite communication systems to achieve several orders of magnitude increase in system capacity and to significantly improve the spectral efficiency.
no code implementations • 6 May 2022 • Wali Ullah Khan, Eva Lagunas, Asad Mahmood, Zain Ali, Muhammad Asif Symeon Chatzinotas, Björn Ottersten
Reflecting intelligent surfaces (RIS) has gained significant attention due to its high energy and spectral efficiency in next-generation wireless networks.
no code implementations • 31 Mar 2022 • Wali Ullah Khan, Eva Lagunas, Zain Ali, Muhammad Awais Javed, Manzoor Ahmed, Symeon Chatzinotas, Björn Ottersten, Petar Popovski
Unmanned Aerial Vehicles (UAVs) are an important component of next-generation wireless networks that can assist in high data rate communications and provide enhanced coverage. Their high mobility and aerial nature offer deployment flexibility and low-cost infrastructure support to existing cellular networks and provide many applications that rely on mobile wireless communications.
no code implementations • 5 Dec 2021 • Ziyang Cheng, Linlong Wu, Bowen Wang, Bhavani Shankar M. R., Björn Ottersten
In millimeter-wave (mmWave) dual-function radar-communication (DFRC) systems, hybrid beamforming (HBF) is recognized as a promising technique utilizing a limited number of radio frequency chains.
no code implementations • 23 Sep 2021 • Wali Ullah Khan, Eva Lagunas, Asad Mahmood, Zain Ali, Symeon Chatzinotas, Björn Ottersten, Octavia A. Dobre
This paper proposes a new optimization approach to enhance the spectral efficiency of nonorthogonal multiple access (NOMA)-BC network.
no code implementations • 8 Sep 2021 • Nitesh Sahu, Linlong Wu, Prabhu Babu, Bhavani Shankar M. R., Björn Ottersten
Source localization plays a key role in many applications including radar, wireless and underwater communications.
no code implementations • 23 Aug 2021 • Linlong Wu, Kumar Vijay Mishra, Bhavani Shankar M. R., Björn Ottersten
Optimal allocation of shared resources is key to deliver the promise of jointly operating radar and communications systems.
no code implementations • 29 Jul 2021 • Linlong Wu, Kumar Vijay Mishra, Bhavani Shankar M. R., Björn Ottersten
In this paper, we focus on a heterogeneous radar and communication network (HRCN), which consists of various generic radars for multiple target tracking (MTT) and wireless communications for multiple users.
no code implementations • 14 Jul 2021 • Wallace A. Martins, Symeon Chatzinotas, Björn Ottersten
This work addresses the issue of interference generated by co-channel users in downlink multi-antenna multicarrier systems with frequency-packed faster-than-Nyquist (FTN) signaling.
no code implementations • 20 Jan 2021 • Hayder Al-Hraishawi, Symeon Chatzinotas, Björn Ottersten
Besides conventional geostationary (GSO) satellite broadband communication services, non-geostationary (NGSO) satellites are envisioned to support various new communication use cases from countless industries.
no code implementations • 28 Dec 2020 • Saeid Sedighi, M. R. Bhavani Shankar, Mojtaba Soltanalian, Björn Ottersten
Specifically, we first investigate the identifiability conditions for the DoA estimation problem from one-bit SLA data and establish an equivalency with the case when DoAs are estimated from infinite-bit unquantized measurements.
no code implementations • 10 Dec 2020 • Anshu Mukherjee, Björn Ottersten, Le-Nam Tran
In the first method we capitalize on the accelerated DC algorithm which requires solving a sequence of convex subproblems, for which we propose an efficient iterative algorithm where each iteration admits a closed-form solution.
Information Theory Signal Processing Information Theory
no code implementations • 30 Nov 2020 • Yun Ai, Felipe A. P. de Figueiredo, Long Kong, Michael Cheffena, Symeon Chatzinotas, Björn Ottersten
Reconfigurable intelligent surfaces (RIS) is considered as a revolutionary technique to improve the wireless system performance by reconfiguring the radio wave propagation environment artificially.
no code implementations • 10 Nov 2020 • Steven Kisseleff, Symeon Chatzinotas, Björn Ottersten
Challenging environments comprise a range of scenarios, which share the fact that it is extremely difficult to establish a communication link using conventional technology due to many impairments typically associated with the propagation medium and increased signal scattering.
no code implementations • 8 Nov 2020 • Maha Alodeh, Björn Ottersten
This paper tackles the problem of the simultaneous interference among the multiple users in the downlink of a wireless multiantenna system.
no code implementations • 7 Nov 2020 • Abderrahmane Mayouche, Wallace A. Martins, Christos G. Tsinos, Symeon Chatzinotas, Björn Ottersten
In this work, we consider secure communications in wireless multi-user (MU) multiple-input single-output (MISO) systems with channel coding in the presence of a multi-antenna eavesdropper (Eve).
no code implementations • 4 Nov 2020 • Ruizhi Hu, Bhavani Shankar Mysore Rama Rao, Ahmed Murtada, Mohammad Alaee-Kerahroodi, Björn Ottersten
In this paper, a novel $l_1$-regularized, consensus alternating direction method of multipliers (CADMM) based algorithm is proposed to mitigate artifacts by exploiting a widely-distributed radar system's spatial diversity.
no code implementations • 2 Sep 2020 • Steven Kisseleff, Wallace A. Martins, Hayder Al-Hraishawi, Symeon Chatzinotas, Björn Ottersten
The concept of Smart Cities has been introduced as a way to benefit from the digitization of various ecosystems at a city level.
no code implementations • 24 Aug 2020 • Duc-Dung Tran, Shree Krishna Sharma, Symeon Chatzinotas, Isaac Woungang, Björn Ottersten
The achieved results show that MIMO NOMA can serve multiple users simultaneously using a smaller blocklength compared with MIMO OMA, thus demonstrating the benefits of MIMO NOMA for SPC in minimizing the transmission latency.
no code implementations • 12 Aug 2020 • Ke-Xin Li, Li You, Jiaheng Wang, Xiqi Gao, Christos G. Tsinos, Symeon Chatzinotas, Björn Ottersten
We show that, in this case, the design of precoding vectors can be simplified into that of scalar variables, for which an effective algorithm is developed.
no code implementations • 29 Jul 2020 • Saeid Sedighi, Kumar Vijay Mishra, M. R. Bhavani Shankar, Björn Ottersten
To support the low-capacity links to the fusion center (FC), the range estimates obtained at individual sensors are then converted to one-bit data.
no code implementations • 8 Jul 2020 • Hieu V. Nguyen, Van-Dinh Nguyen, Octavia A. Dobre, Shree Krishna Sharma, Symeon Chatzinotas, Björn Ottersten, Oh-Soon Shin
This paper investigates the combined benefits of full-duplex (FD) and cell-free massive multiple-input multipleoutput (CF-mMIMO), where a large number of distributed access points (APs) having FD capability simultaneously serve numerous uplink and downlink user equipments (UEs) on the same time-frequency resources.
no code implementations • 2 Jun 2020 • Gabriela Lewenfus, Wallace Alves Martins, Symeon Chatzinotas, Björn Ottersten
We tackle the problem of forecasting network-signal snapshots using past signal measurements acquired by a subset of network nodes.
no code implementations • 28 May 2020 • Arsham Mostaani, Thang X. Vu, Symeon Chatzinotas, Björn Ottersten
Motivated by these recent developments, in this paper, we perform an indirect design of the communications in a multi-agent system (MAS) in which agents cooperate to maximize the averaged sum of discounted one-stage rewards of a collaborative task.
no code implementations • 14 May 2020 • Ashok Bandi, Bhavani Shankar Mysore R, Symeon Chatzinotas, Björn Ottersten
This paper studies the joint design of user grouping, scheduling (or admission control) and precoding to optimize energy efficiency (EE) for multigroup multicast scenarios in single-cell multiuser MISO downlink channels.
no code implementations • 20 Dec 2019 • Konstantinos Papadopoulos, Enjie Ghorbel, Djamila Aouada, Björn Ottersten
This paper extends the Spatial-Temporal Graph Convolutional Network (ST-GCN) for skeleton-based action recognition by introducing two novel modules, namely, the Graph Vertex Feature Encoder (GVFE) and the Dilated Hierarchical Temporal Convolutional Network (DH-TCN).
Ranked #14 on
Action Recognition
on NTU RGB+D 120
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.
no code implementations • 23 May 2019 • Hassan Afzal, Djamila Aouada, Michel Antunes, David Fofi, Bruno Mirbach, Björn Ottersten
In this work, we propose a sensor fusion framework based on a weighted bi-objective optimization for refinement of extrinsic calibration tailored for RGB-D multi-view systems.
1 code implementation • 10 May 2019 • Yang Yang, Marius Pesavento, Zhi-Quan Luo, Björn Ottersten
Interestingly, when the approximation subproblem is solved by a descent algorithm, convergence of a subsequence to a stationary point is still guaranteed even if the approximation subproblem is solved inexactly by terminating the descent algorithm after a finite number of iterations.
no code implementations • 10 Apr 2019 • Konstantinos Papadopoulos, Girum Demisse, Enjie Ghorbel, Michel Antunes, Djamila Aouada, Björn Ottersten
The Dense Trajectories concept is one of the most successful approaches in action recognition, suitable for scenarios involving a significant amount of motion.
no code implementations • 28 Jun 2018 • Yang Yang, Marius Pesavento, Symeon Chatzinotas, Björn Ottersten
The proposed framework has several attractive features, namely, i) flexibility, as different choices of the approximate function lead to different type of algorithms; ii) fast convergence, as the problem structure can be better exploited by a proper choice of the approximate function and the stepsize is calculated by the line search; iii) low complexity, as the approximate function is convex and the line search scheme is carried out over a differentiable function; iv) guaranteed convergence to a stationary point.
no code implementations • 23 Oct 2017 • Anestis Tsakmalis, Symeon Chatzinotas, Björn Ottersten
The cognitive part of this sequential probing process is the selection of the power levels of the Secondary Users (SUs) which aims to learn the PU interference constraint with a minimum number of probing attempts while setting a limit on the number of harmful probing-induced interference events or equivalently of NACK packet observations over a time window.
2 code implementations • 1 Apr 2014 • Emil Björnson, Mats Bengtsson, Björn Ottersten
A high signal power is achieved by transmitting the same data signal from all antennas, but with different amplitudes and phases, such that the signal components add coherently at the user.
Information Theory Information Theory
1 code implementation • 18 Sep 2012 • Emil Björnson, Per Zetterberg, Mats Bengtsson, Björn Ottersten
The capacity of ideal MIMO channels has a high-SNR slope that equals the minimum of the number of transmit and receive antennas.
Information Theory Information Theory
1 code implementation • 11 Jul 2012 • Emil Björnson, Marios Kountouris, Mats Bengtsson, Björn Ottersten
Analytic results are derived to show how user selection, spatial correlation, heterogeneous user conditions, and imperfect channel acquisition (quantization or estimation errors) affect the performance when sending the maximal number of streams or one stream per scheduled user---the two extremes in data stream allocation.
Information Theory Information Theory