pwc-archive/papers-with-abstracts huggingface dataset:
EEGM2: An Efficient Mamba-2-Based Self-Supervised Framework for Long-Sequence EEG Modeling
Authors: Jiazhen Hong, Geoffrey Mackellar, Soheila Ghane
Date: 2025-02-25 00:00:00
Tasks: EEG, Electroencephalogram (EEG), Mamba, State Space Models

Deep learning has achieved significant progress in the development of electroencephalogram (EEG) foundation models, with Transformer-based architectures excelling at capturing long-range dependencies. However, their quadratic computational complexity presents challenges in memory efficiency, training, and inference speed, limiting their scalability and generalizability as a foundation model. In this paper, we propose EEGM2, a self-supervised framework based on structured state space duality (SSD) that overcomes these limitations. EEGM2 introduces three key innovations: (1) a reconstruction-based framework that captures both local and global EEG features through Mamba-2 structured state space models, (2) a spatiotemporal-aware loss function that enhances robustness to noise and preserves spectral information, and (3) a multi-branch receptive field input embedding strategy that improves cross-subject generalization and stability for EEG sequences of varying lengths. In comparison to traditional pretraining methods, on raw EEG or latent representation spaces, EEGM2 shows superior performance on long-sequence tasks, where conventional models struggle. Our experimental results on six EEG datasets validate that EEGM2 not only achieves state-of-the-art cross-domain accuracy but also reduces computational overhead, making it a more efficient solution for deployment on resource-constrained BCI devices.
Beamforming with hybrid reconfigurable parasitic antenna arrays
Authors: Nitish Vikas Deshpande, Miguel Rodrigo Castellanos, Saeed R. Khosravirad, Jinfeng Du, Harish Viswanathan, Robert W. Heath Jr
Date: 2025-02-25 00:00:00

A parasitic reconfigurable antenna array is a low-power approach for beamforming using passive tunable elements. Prior work on reconfigurable antennas in communication theory is based on ideal radiation pattern abstractions. It does not address the problem of physical realizability. Beamforming with parasitic elements is inherently difficult because mutual coupling creates non-linearity in the beamforming gain objective. We develop a multi-port circuit-theoretic model of the hybrid array with parasitic elements and antennas with active RF chain validated through electromagnetic simulations with a dipole array. We then derive the beamforming weight of the parasitic element using the theoretical beam pattern expression for the case of a single active antenna and multiple parasitic elements. We show that the parasitic beamforming is challenging because the weights are subject to coupled magnitude and phase constraints. We simplify the beamforming optimization problem using a shift-of-origin transformation to the typical unit-modulus beamforming weight. With this transformation, we derive a closed-form solution for the reconfigurable parasitic reactance. We generalize this solution to the multi-active multi-parasitic hybrid array operating in a multi-path channel. Our proposed hybrid architecture with parasitic elements outperforms conventional architectures in terms of energy efficiency.
Feedback-Free Resource Scheduling for Flexible Multi-BS Cooperation in FD-RAN
Authors: Jingbo Liu, Jiacheng Chen, Zeyu Sun, Bo Qian, Haibo Zhou
Date: 2025-02-25 00:00:00
Tasks: Scheduling

Flexible cooperation among base stations (BSs) is critical to improve resource utilization efficiency and meet personalized user demands. However, its practical implementation is hindered by the current radio access network (RAN), which relies on the coupling of uplink and downlink transmissions and channel state information feedback with inherent issues such as overheads and delays. To overcome these limitations, we consider the fully-decoupled RAN (FD-RAN), in which uplink and downlink functionalities are independent, and feedback-free MIMO transmission is adopted at the physical layer. To further deliver flexible cooperation in FD-RAN, we study feedback-free downlink multi-BS resource scheduling under the practical scheduling process. The problem is considered based on network load conditions. In heavy-load states where it is impossible for all user demands to be met, an optimal greedy algorithm is proposed, maximizing the weighted sum of user demand satisfaction rates. In light-load states where at least one solution exists to satisfy all user demands, an optimal two-stage resource allocation algorithm is designed to further minimize network energy consumption by leveraging the flexibility of cooperation. Extensive simulations validate the superiority of proposed algorithms in performance and running time, and highlight the potential for realizing flexible cooperation in practice.
Hybrid Beamforming with Orthogonal delay-Doppler Division Multiplexing Modulation for Terahertz Sensing and Communication
Authors: Meilin Li, Chong Han, Shi Jin
Date: 2025-02-25 00:00:00
Tasks: ISAC

The Terahertz band holds a promise to enable both super-accurate sensing and ultra-fast communication. However, challenges arise that severe Doppler effects call for a waveform with high Doppler robustness while severe propagation path loss urges for an ultra-massive multiple-input multiple-output (UM-MIMO) structure. To tackle these challenges, hybrid beamforming with orthogonal delay-Doppler multiplexing modulation (ODDM) is investigated in this paper. First, the integration of delay-Doppler waveform and MIMO is explored by deriving a hybrid beamforming-based UM-MIMO ODDM input-output relation. Then, a multi-dimension sensing algorithm on target azimuth angle, elevation angle, range and velocity is proposed, which features low complexity and high accuracy. Finally, a sensing-centric hybrid beamforming is proposed to design the sensing combiner by minimizing the Cram\'er-Rao lower bounds (CRLB) of angles. After that, the precoder that affects both communication and sensing is then designed to maximize the spectral efficiency. Numerical results show that the sensing accuracy of the proposed sensing algorithm is sufficiently close to CRLB. Moreover, the proposed hybrid beamforming design allows to achieve maximal spectral efficiency, millimeter-level range estimation accuracy, millidegree-level angle estimation accuracy and millimeter-per-second-level velocity estimation accuracy. Take-away lessons are two-fold. Combiner design is critical especially for sensing, which is commonly neglected in hybrid beamforming design for communication. Furthermore, the optimization problems for communication and sensing can be decoupled and solved independently, significantly reducing the computational complexity of the THz monostatic ISAC system.
Joint Communication and Radar Sensing for Terahertz Space-Air-Ground Integrated Networks (SAGIN)
Authors: Chong Han, Weijun Gao, Zhepu Yin, Chuang Yang, Mugen Peng, Wenjun Zhang
Date: 2025-02-25 00:00:00

The transition from isolated systems to integrated solutions has driven the development of space-air-ground integrated networks (SAGIN) as well as the integration of communication and radar sensing functionalities. By leveraging the unique properties of the Terahertz (THz) band, THz joint communication and radar sensing (JCRS) supports high-speed communication and precise sensing, addressing the growing demands of SAGIN for connectivity and environmental awareness. However, most existing THz studies focus on terrestrial and static scenarios, with limited consideration for the dynamic and non-terrestrial environments of SAGIN. In this paper, the THz JCRS techniques for SAGIN are comprehensively investigated. Specifically, propagation characteristics and channel models of THz waves in non-terrestrial environments are analyzed. A link capacity comparison with millimeter-wave, THz, and free-space optical frequency bands is conducted to highlight the advantages of THz frequencies. Moreover, novel JCRS waveform design strategies are presented to achieve mutual merit of communication and radar sensing, while networking strategies are developed to overcome challenges in SAGIN such as high mobility. Furthermore, advancements in THz device technologies, including antennas and amplifiers, are reviewed to assess their roles in enabling practical JCRS implementations.
Terahertz Aerospace Communications: Enabling Technologies and Future Directions
Authors: Weijun Gao, Chong Han, Zhi Chen, Yong Chen, Yuanzhi He, Wenjun Zhang
Date: 2025-02-25 00:00:00

To achieve ubiquitous connectivity in next-generation networks through aerospace communications while maintaining high data rates, Terahertz (THz) band communications (0.1-10 THz) with large continuous bandwidths are considered a promising candidate technology. However, key enabling techniques and practical implementations of THz communications for aerospace applications remain limited. In this paper, the wireless channel characteristics, enabling communication techniques, and networking strategies for THz aerospace communications are investigated, aiming to assess their feasibility and encourage future research efforts toward system realization. Specifically, the wireless channel characteristics across various altitudes and scenarios are first analyzed, focusing on modeling the interaction between the THz wave and the external environment, from ground to outer space. Next, key enabling communication technologies, including multiple-input multiple-output (MIMO) technique, beam alignment and tracking, integrated communication and radar sensing (ICARS), and resource allocation for networking are discussed. Finally, the existing challenges and possible future directions are summarized and discussed.
Waveguide Division Multiple Access for Pinching-Antenna Systems (PASS)
Authors: Jingjing Zhao, Xidong Mu, Kaiquan Cai, YanBo Zhu, Yuanwei Liu
Date: 2025-02-25 00:00:00
Tasks: Position

A novel concept of waveguide division multiple access (WDMA) is proposed for multi-user pinching-antenna systems (PASS). The key principle of WDMA is to allocate each user with a dedicated waveguide, which is regarded as a new type of radio resources, so as to facilitate multi-user communications. By adjusting the activation positions of pinching antennas (PAs) over each waveguide, the pinching beamforming can be exploited for intended user signal enhancement and inter-user interference mitigation. Considering both ideal continuous and practical discrete PA position activation schemes, a joint power allocation and pinching beamforming optimization problem is formulated for the maximization of the sum rate. An alternating optimization-based algorithm is developed to address the formulated nonconvex problem. For solving the power allocation subproblem, the successive convex approximation method is invoked. For the pinching beamforming design subproblem, a penalty-based gradient ascent algorithm is first developed for the continuous PA activation case. Then, for the discrete PA activation case, a matching theory-based algorithm is proposed to achieve the near-optimal performance but with a low complexity. Numerical results unveil that: 1) For both continuous and discrete activation cases, PASS can achieve a significant performance gain over conventional fixed-position antenna systems; 2) the proposed WDMA can effectively underpin multi-user communications with the near orthogonality in free space achieved by the pinching beamforming; and 3) the performance gap between the discrete and continuous activation cases can be significantly alleviated with practically feasible numbers of PA candidate positions.
Joint Beamforming and 3D Location Optimization for Multi-User Holographic UAV Communications
Authors: Chandan Kumar Sheemar, Asad Mahmood, Christo Kurisummoottil Thomas, George C. Alexandropoulos, Jorge Querol, Symeon Chatzinotas, Walid Saad
Date: 2025-02-24 00:00:00
Tasks: Position

This paper pioneers the field of multi-user holographic unmanned aerial vehicle (UAV) communications, laying a solid foundation for future innovations in next-generation aerial wireless networks. The study focuses on the challenging problem of jointly optimizing hybrid holographic beamforming and 3D UAV positioning in scenarios where the UAV is equipped with a reconfigurable holographic surface (RHS) instead of conventional phased array antennas. Using the unique capabilities of RHSs, the system dynamically adjusts both the position of the UAV and its hybrid beamforming properties to maximize the sum rate of the network. To address this complex optimization problem, we propose an iterative algorithm combining zero-forcing digital beamforming and a gradient ascent approach for the holographic patterns and the 3D position optimization, while ensuring practical feasibility constraints. The algorithm is designed to effectively balance the trade-offs between power, beamforming, and UAV trajectory constraints, enabling adaptive and efficient communications, while assuring a monotonic increase in the sum-rate performance. Our numerical investigations demonstrate that the significant performance improvements with the proposed approach over the benchmark methods, showcasing enhanced sum rate and system adaptability under varying conditions.
Joint Holographic Beamforming and User Scheduling with Individual QoS Constraints
Authors: Chandan Kumar Sheemar, Christo Kurisummoottil Thomas, George C. Alexandropoulos, Jorge Querol, Symeon Chatzinotas, Walid Saad
Date: 2025-02-24 00:00:00
Tasks: Scheduling

Reconfigurable holographic surfaces (RHS) have emerged as a transformative material technology, enabling dynamic control of electromagnetic waves to generate versatile holographic beam patterns. This paper addresses the problem of joint hybrid holographic beamforming and user scheduling under per-user minimum quality-of-service (QoS) constraints, a critical challenge in resource-constrained networks. However, such a problem results in mixed-integer non-convex optimization, making it difficult to identify feasible solutions efficiently. To overcome this challenge, we propose a novel iterative optimization framework that jointly solves the problem to maximize the RHS-assisted network sum-rate, efficiently managing holographic beamforming patterns, dynamically scheduling users, and ensuring the minimum QoS requirements for each scheduled user. The proposed framework relies on zero-forcing digital beamforming, gradient-ascent-based holographic beamformer optimization, and a greedy user selection principle. Our extensive simulation results validate the effectiveness of the proposed scheme, demonstrating their superior performance compared to the benchmark algorithms in terms of sum-rate performance, while meeting the minimum per-user QoS constraints
Enhancing CoMP-RSMA Performance with Movable Antennas: A Meta-Learning Optimization Framework
Authors: Ali Amhaz, Shreya Khisa, Mohamed Elhattab, Chadi Assi, Sanaa Sharafeddine
Date: 2025-02-24 00:00:00
Tasks: Meta-Learning

This study investigates a downlink rate-splitting multiple access (RSMA) scenario in which multiple base stations (BSs), employing a coordinated multi-point (CoMP) transmission scheme, serve users equipped with movable antenna (MA) technology. Unlike traditional fixed-position antennas (FPAs), which are subject to random variations in wireless channels, MAs can be strategically repositioned to locations with more favorable channel conditions, thereby achieving enhanced spatial diversity gains.To leverage these advantages and maximize the achievable sum rate, we formulate an optimization problem that jointly determines the optimal transmit beamforming vectors at the BSs, the common stream allocation for different users, and the optimal positioning of the MAs, all while ensuring compliance with quality of service (QoS) constraints. However, the formulated problem is non-convex and computationally challenging due to the strong interdependence among the optimization variables. Traditional methods for solving large-scale optimization problems typically incur prohibitively high computational complexity. To address the above challenge, we propose a gradient-based meta-learning (GML) algorithm that operates without pre-training and is well-suited for handling large-scale optimization tasks. Numerical results demonstrate the effectiveness and accuracy of the proposed approach, achieving near-optimal performance (exceeding 97% compared to the optimal solution). Moreover, the MA-enabled CoMP-RSMA model significantly outperforms conventional benchmark schemes, yielding performance gains of up to 190% over the spatial division multiple access (SDMA) scheme and 80% over the RSMA FPA-based model. Finally, the proposed approach is shown to mitigate the sum-rate limitations imposed by interference in SDMA, achieving superior performance with fewer BSs.
CLEP-GAN: An Innovative Approach to Subject-Independent ECG Reconstruction from PPG Signals
Authors: Xiaoyan Li, Shixin Xu, Faisal Habib, Neda Aminnejad, Arvind Gupta, Huaxiong Huang
Date: 2025-02-24 00:00:00
Tasks: Contrastive Learning, Diversity

This study addresses the challenge of reconstructing unseen ECG signals from PPG signals, a critical task for non-invasive cardiac monitoring. While numerous public ECG-PPG datasets are available, they lack the diversity seen in image datasets, and data collection processes often introduce noise, complicating ECG reconstruction from PPG even with advanced machine learning models. To tackle these challenges, we first introduce a novel synthetic ECG-PPG data generation technique using an ODE model to enhance training diversity. Next, we develop a novel subject-independent PPG-to-ECG reconstruction model that integrates contrastive learning, adversarial learning, and attention gating, achieving results comparable to or even surpassing existing approaches for unseen ECG reconstruction. Finally, we examine factors such as sex and age that impact reconstruction accuracy, emphasizing the importance of considering demographic diversity during model training and dataset augmentation.
AIRIS2 : a Smart Gateway Diversity Algorithm for Very High-Throughput Satellite Systems
Authors: Justin Cano, Jonathan Israël, Laurent Féral
Date: 2025-02-24 00:00:00
Tasks: Decision Making, Diversity

Satellite communication systems are shifting to higher frequency bands (Ka, Q/V, W) to support more data-intensive services and alleviate spectral congestion. However, the use of Extremely High Frequencies, typically above 20 GHz, causes significant tropospheric impairments, such as rain attenuation, which can causes system outages. To mitigate these effects, Smart Gateway Diversity (SGD) has emerged as a promising method for maximizing feeder link availability through an adaptive site diversity scheme. However, implementing such technique requires a decision-making policy to dynamically select the optimal set of gateways and prevent outages. This paper introduces AIRIS2, a deep learning algorithm that anticipates short-term rain events from rain attenuation measurement to enable efficient gateway switching. The approach is validated from five years of measured time series collected at Ka and Q/V bands at various sites and climatic conditions.
SpikACom: A Neuromorphic Computing Framework for Green Communications
Authors: Yanzhen Liu, Zhijin Qin, Yongxu Zhu, Geoffrey Ye Li
Date: 2025-02-24 00:00:00
Tasks: Semantic Communication

The ever-growing power consumption of wireless communication systems necessitates more energy-efficient algorithms. This paper introduces SpikACom ({Spik}ing {A}daptive {Com}munication), a neuromorphic computing-based framework for power-intensive wireless communication tasks. SpikACom leverages brain-inspired spiking neural networks (SNNs) for efficient signal processing. It is designed for dynamic wireless environments, helping to mitigate catastrophic forgetting and facilitate adaptation to new circumstances. Moreover, SpikACom is customizable, allowing flexibly integration of domain knowledge to enhance it interpretability and efficacy. We validate its performance on fundamental wireless communication tasks, including task-oriented semantic communication, multiple-input multiple-output (MIMO) beamforming, and orthogonal frequency-division multiplexing (OFDM) channel estimation. The simulation results show that SpikACom significantly reduces power consumption while matching or exceeding the performance of conventional algorithms. This study highlights the potential of SNNs for enabling greener and smarter wireless communication systems.
Conditional Generative Adversarial Networks for Channel Estimation in RIS-Assisted ISAC Systems
Authors: Alice Faisal, Ibrahim Al-Nahhal, Kyesan Lee, Octavia A. Dobre, Hyundong Shin
Date: 2025-02-24 00:00:00
Tasks: Integrated sensing and communication, ISAC

Integrated sensing and communication (ISAC) technology has been explored as a potential advancement for future wireless networks, striving to effectively use spectral resources for both communication and sensing. The integration of reconfigurable intelligent surfaces (RIS) with ISAC further enhances this capability by optimizing the propagation environment, thereby improving both the sensing accuracy and communication quality. Within this domain, accurate channel estimation is crucial to ensure a reliable deployment. Traditional deep learning (DL) approaches, while effective, can impose performance limitations in modeling the complex dynamics of wireless channels. This paper proposes a novel application of conditional generative adversarial networks (CGANs) to solve the channel estimation problem of an RIS-assisted ISAC system. The CGAN framework adversarially trains two DL networks, enabling the generator network to not only learn the mapping relationship from observed data to real channel conditions but also to improve its output based on the discriminator network feedback, thus effectively optimizing the training process and estimation accuracy. The numerical simulations demonstrate that the proposed CGAN-based method improves the estimation performance effectively compared to conventional DL techniques. The results highlight the CGAN's potential to revolutionize channel estimation, paving the way for more accurate and reliable ISAC deployments.
A First Look at the Performance Enhancement Potential of Fluid Reconfigurable Intelligent Surface
Authors: Abdelhamid Salem, Kai-Kit Wong, George Alexandropoulos, Chan-Byoung Chae, Ross Murch
Date: 2025-02-24 00:00:00
Tasks: Position

The fluid antenna concept represents shape-flexible and position-flexible antenna technologies designed to enhance wireless communication applications. In this paper, we apply this concept to reconfigurable intelligent surfaces (RISs), introducing fluid RIS (FRIS), where each tunably reflecting element becomes a fluid element with additional position reconfigurability. This new paradigm is referred to as fluid RIS (FRIS). We investigate an FRIS-programmable wireless channel, where the fluid meta-surface is divided into non-overlapping subareas, each acting as a fluid element that can dynamically adjust both its position and phase shift of the reflected signal. We first analyze the single-user, single-input single-output (SU-SISO) channel, in which a single-antenna transmitter communicates with a single-antenna receiver via an FRIS. The achievable rate is maximized by optimizing the fluid elements using a particle swarm optimization (PSO)- based approach. Next, we extend our analysis to the multi-user, multiple-input single-output (MU-MISO) case, where a multi-antenna base station (BS) transmits individual data streams to multiple single-antenna users via an FRIS. In this case, the joint optimization of the positions and phase shifts of the FRIS element, as well as the BS precoding to maximize the sum-rate is studied. To solve the problem, a combination of techniques including PSO, semi-definite relaxation (SDR), and minimum mean square error (MMSE) is proposed. Numerical results demonstrate that the proposed FRIS approach significantly outperforms conventional RIS configurations in terms of achievable rate performance.