pwc-archive/papers-with-abstracts huggingface dataset:
Realization of Reconfigurable Intelligent Surfaces with Space-Time Coded Metasurfaces
Authors: Mehdi Gholami, Soheil Khajavi, Mohammad Neshat, Simon Tewes, Aydin Sezgin
Date: 2024-10-27 00:00:00

This paper presents experimental realization of a reconfigurable intelligent surface (RIS) using space-time coding metasurfaces to enable concurrent beam steering and data modulation. The proposed approach harnesses the capabilities of metasurfaces, allowing precise temporal control over individual unit cells of the RIS. We show that by employing proper binary codes manipulating the state of unit cells, the RIS can act as a digital data modulator with beam steering capability. We describe the experimental setup and computational tools, followed by validation through harmonic generation and investigation of beam steering and data modulation. Additionally, four digital modulation schemes are evaluated. By implementing customized binary codes, constellations under varying conditions are compared, showcasing the potential for real-world applications. This study offers new insights into the practical implementation of RIS for advanced wireless communication systems.
Trajectory Reconstruction through a Gaussian Adaptive Selective Outlier Rejecting Smoother
Authors: Arslan Majal, Aamir Hussain Chughtai
Date: 2024-10-27 00:00:00

Trajectory Reconstruction (TR) is vital for accurately mapping movement patterns and validating analyses, especially in fields like robotics, biomechanics, and environmental tracking, where data might be missing or affected by outliers. Improving Trajectory estimation by employing Gaussian smoothing techniques in the presence of non-Gaussian noise is the subject of this work. We consider the case where data is collected from independent sensors. A variational Bayesian (VB) based Unscented Raunch-Tung-Striebel smoothing (URTSS) scheme is proposed which adopts a vectorized weighing mechanism for the measurement covariance matrix to selectively remove contaminated measurements at each time step. To improve our outlier mitigation, we model our outlier characteristics as a Gamma distribution and dynamically learn the parameters of this distribution from data. We verify the performance of our proposed smoother by a range of simulations and experimental data. We also propose a robustness criterion for smoothers based on the Kullback-Leibler (KL) divergence and show that our proposed method complies with this criterion.
Unleashing Dynamic Range and Resolution in Unlimited Sensing Framework via Novel Hardware
Authors: Yuliang Zhu, Ayush Bhandari
Date: 2024-10-26 00:00:00
Tasks: Quantization

Conventional digitization based on the Shannon-Nyquist method, implemented via analog-to-digital converters (ADCs), faces fundamental limitations. High-dynamic-range (HDR) signals often get clipped or saturated in practice. Given a fixed bit budget, one must choose between minimizing quantization noise or accommodating HDR inputs. The Unlimited Sensing Framework (USF) eliminates saturation by incorporating nonlinear folding in analog hardware, resulting in modulo signals. Quantizing or digitizing modulo signals enables low quantization noise as the modulo representation maps HDR signals into low-dynamic-range (LDR) samples. In the context of USF, the core innovation of this paper is a novel, low-cost, integrator-based efficient modulo ADC hardware implementation that imposes no restrictions on folding rates, enabling significantly HDR capture. The feasibility of this design is demonstrated by hardware experiments showcasing clear advantages across different quantitative performance metrics. These include capturing HDR signals with a 60-fold increase in dynamic range, achieving up to 5 Effective Number of Bits (ENOBs), and improving Signal-to-Noise and Distortion (SINAD) by 30 dB.
Multi-IRS Enhanced Wireless Coverage: Deployment Optimization Based on Large-Scale Channel Knowledge
Authors: Min Fu, Lipeng Zhu, Rui Zhang
Date: 2024-10-26 00:00:00
Tasks: Combinatorial Optimization

In this paper, we study the intelligent reflecting surface (IRS) deployment problem where a number of IRSs are optimally placed in a target area to improve its signal coverage with the serving base station (BS). To achieve this, we assume that there is a given set of candidate sites in the target area for deploying IRSs and divide the area into multiple grids of identical size. Then, we derive the average channel power gains from the BS to IRS in each candidate site and from this IRS to any grid in the target area in terms of IRS deployment parameters, including its size, position, height, and orientation. Thus, we are able to approximate the average cascaded channel power gain from the BS to each grid via any IRS, assuming an effective IRS reflection gain based on the large-scale channel knowledge only. Next, we formulate a multi-IRS deployment optimization problem to minimize the total deployment cost by selecting a subset of candidate sites for deploying IRSs and jointly optimizing their heights, orientations, and numbers of reflecting elements while satisfying a given coverage rate performance requirement over all grids in the target area. To solve this challenging combinatorial optimization problem, we first reformulate it as an integer linear programming problem and solve it optimally using the branch-and-bound (BB) algorithm. In addition, we propose an efficient successive refinement algorithm to further reduce computational complexity. Simulation results demonstrate that the proposed lower-complexity successive refinement algorithm achieves near-optimal performance but with significantly reduced running time compared to the proposed optimal BB algorithm, as well as superior performance-cost trade-off than other baseline IRS deployment strategies.
Gaussian Process Regression-Based Lithium-Ion Battery End-of-Life Prediction Model under Various Operating Conditions
Authors: Seyeong Park, Jaewook Lee, Seongmin Heo
Date: 2024-10-25 00:00:00

For the efficient and safe use of lithium-ion batteries, diagnosing their current state and predicting future states are crucial. Although there exist many models for the prediction of battery cycle life, they typically have very complex input structures, making it very difficult and expensive to develop such models. As an alternative, in this work, a model that predicts the nominal end-of-life using only operating conditions as input is proposed. Specifically, a total of 100 battery degradation data were generated using a pseudo two-dimensional model with three major operating conditions: charging C-rate, ambient temperature and depth-of-discharge. Then, a Gaussian process regression-based model was developed to predict the nominal end-of-life using these operating conditions as the inputs. To improve the model accuracy, novel kernels were proposed, which are tailored to each operating condition. The proposed kernels reduced the lifetime prediction error by 46.62% compared to the conventional kernels.
Foundation Models in Electrocardiogram: A Review
Authors: Yu Han, Xiaofeng Liu, Xiang Zhang, Cheng Ding
Date: 2024-10-24 00:00:00
Tasks: Arrhythmia Detection, Representation Learning, Survey

The electrocardiogram (ECG) is ubiquitous across various healthcare domains, such as cardiac arrhythmia detection and sleep monitoring, making ECG analysis critically essential. Traditional deep learning models for ECG are task-specific, with a narrow scope of functionality and limited generalization capabilities. Recently, foundation models (FMs), also known as large pre-training models, have fundamentally reshaped the scheme of model design and representation learning, enhancing the performance across a variety of downstream tasks. This success has drawn interest in the exploration of FMs to address ECG-based medical challenges concurrently. This survey provides a timely, comprehensive and up-to-date overview of FMs for large-scale ECG-FMs. First, we offer a brief background introduction to FMs. Then, we discuss the model architectures, pre-training methods, and adaptation approaches of ECG-FMs from a methodology perspective. Despite the promising opportunities of ECG-FMs, we also outline the challenges and potential future directions. Overall, this survey aims to provide researchers and practitioners with insights into the research of ECG-FMs on theoretical underpinnings, domain-specific applications, and avenues for future exploration.
Multi-Modal Transformer and Reinforcement Learning-based Beam Management
Authors: Mohammad Ghassemi, Han Zhang, Ali Afana, Akram Bin Sediq, Melike Erol-Kantarci
Date: 2024-10-22 00:00:00
Tasks: Beam Prediction, Management, reinforcement-learning, Reinforcement Learning, Reinforcement Learning (RL)

Beam management is an important technique to improve signal strength and reduce interference in wireless communication systems. Recently, there has been increasing interest in using diverse sensing modalities for beam management. However, it remains a big challenge to process multi-modal data efficiently and extract useful information. On the other hand, the recently emerging multi-modal transformer (MMT) is a promising technique that can process multi-modal data by capturing long-range dependencies. While MMT is highly effective in handling multi-modal data and providing robust beam management, integrating reinforcement learning (RL) further enhances their adaptability in dynamic environments. In this work, we propose a two-step beam management method by combining MMT with RL for dynamic beam index prediction. In the first step, we divide available beam indices into several groups and leverage MMT to process diverse data modalities to predict the optimal beam group. In the second step, we employ RL for fast beam decision-making within each group, which in return maximizes throughput. Our proposed framework is tested on a 6G dataset. In this testing scenario, it achieves higher beam prediction accuracy and system throughput compared to both the MMT-only based method and the RL-only based method.
Contrastive random lead coding for channel-agnostic self-supervision of biosignals
Authors: Thea Brüsch, Mikkel N. Schmidt, Tommy S. Alstrøm
Date: 2024-10-21 00:00:00
Tasks: Contrastive Learning, EEG

Contrastive learning yields impressive results for self-supervision in computer vision. The approach relies on the creation of positive pairs, something which is often achieved through augmentations. However, for multivariate time series effective augmentations can be difficult to design. Additionally, the number of input channels for biosignal datasets often varies from application to application, limiting the usefulness of large self-supervised models trained with specific channel configurations. Motivated by these challenges, we set out to investigate strategies for creation of positive pairs for channel-agnostic self-supervision of biosignals. We introduce contrastive random lead coding (CRLC), where random subsets of the input channels are used to create positive pairs and compare with using augmentations and neighboring segments in time as positive pairs. We validate our approach by pre-training models on EEG and ECG data, and then fine-tuning them for downstream tasks. CRLC outperforms competing strategies in both scenarios in the channel-agnostic setting. For EEG, the approach additionally outperforms the state-of-the-art reference model. Notably, for EEG tasks CRLC surpasses the current state-of-the-art reference model. While, the state-of-the-art reference model is superior in the ECG task, incorporating CRLC allows us to obtain comparable results. In conclusion, CRLC helps generalization across variable channel setups when training our channel-agnostic model.
Non-invasive Neural Decoding in Source Reconstructed Brain Space
Authors: Yonatan Gideoni, Ryan Charles Timms, Oiwi Parker Jones
Date: 2024-10-20 00:00:00
Tasks: EEG

Non-invasive brainwave decoding is usually done using Magneto/Electroencephalography (MEG/EEG) sensor measurements as inputs. This makes combining datasets and building models with inductive biases difficult as most datasets use different scanners and the sensor arrays have a nonintuitive spatial structure. In contrast, fMRI scans are acquired directly in brain space, a voxel grid with a typical structured input representation. By using established techniques to reconstruct the sensors' sources' neural activity it is possible to decode from voxels for MEG data as well. We show that this enables spatial inductive biases, spatial data augmentations, better interpretability, zero-shot generalisation between datasets, and data harmonisation.
Transferable Multi-Fidelity Bayesian Optimization for Radio Resource Management
Authors: Yunchuan Zhang, Sangwoo Park, Osvaldo Simeone
Date: 2024-10-20 00:00:00
Tasks: Bayesian Optimization, Management

Radio resource allocation often calls for the optimization of black-box objective functions whose evaluation is expensive in real-world deployments. Conventional optimization methods apply separately to each new system configuration, causing the number of evaluations to be impractical under constraints on computational resources or timeliness. Toward a remedy for this issue, this paper introduces a multi-fidelity continual optimization framework that hinges on a novel information-theoretic acquisition function. The new strategy probes candidate solutions so as to balance the need to retrieve information about the current optimization task with the goal of acquiring information transferable to future resource allocation tasks, while satisfying a query budget constraint. Experiments on uplink power control in a multi-cell multi-antenna system demonstrate that the proposed method substantially improves the optimization efficiency after processing a sufficiently large number of tasks.
Integrating Deep Learning for Arrhythmia Detection with Automated Drug Delivery: A Comprehensive Approach to Cardiac Health Monitoring and Treatment
Authors: Praveen Kumar Pandian Shanmuganathan, Vatsal Sivaratri
Date: 2024-10-18 00:00:00
Tasks: Arrhythmia Detection, Diagnostic

Arrhythmias are irregularities in the hearts electrical system which cause rapid and irregular heartbeats. These heart conditions affect over 33 million people globally and significantly increase the risk of severe complications, including stroke, heart failure, and sudden death. Modern screening and treatment approaches, like 12 lead ECG tests and analyzing patient medical history, use frameworks that dont address early onset of conditions and lack sufficient information to optimize treatment plans post diagnosis. This project aimed to enhance cardiac arrhythmias early diagnosis, monitoring, analysis, and treatment using an optimized 5 step patient pathway. We developed deep learning models using ECG, PPG, and SpO2 data to monitor conditions remotely with smartwatches and document arrhythmic episodes with relevant information, including daily patterns. We synthesized these into patient reports suitable for real world clinical, providing enough information to guide treatment decisions before any new diagnostics. For critical care in a hospitalized setting or personalized home care, we developed a novel drug delivery system synchronized with a phone via Bluetooth and uses prescription based or prediction based to deliver medication intravenously at the optimal time. This approach could reduce the need for additional diagnostic tests, streamline patient management, and optimize medication schedules to better align with the individuals physiological needs, significantly improving patient outcomes.
Automatic Classification of Sleep Stages from EEG Signals Using Riemannian Metrics and Transformer Networks
Authors: Mathieu Seraphim, Alexis Lechervy, Florian Yger, Luc Brun, Olivier Etard
Date: 2024-10-18 00:00:00
Tasks: EEG

Purpose: In sleep medicine, assessing the evolution of a subject's sleep often involves the costly manual scoring of electroencephalographic (EEG) signals. In recent years, a number of Deep Learning approaches have been proposed to automate this process, mainly by extracting features from said signals. However, despite some promising developments in related problems, such as Brain-Computer Interfaces, analyses of the covariances between brain regions remain underutilized in sleep stage scoring.Methods: Expanding upon our previous work, we investigate the capabilities of SPDTransNet, a Transformer-derived network designed to classify sleep stages from EEG data through timeseries of covariance matrices. Furthermore, we present a novel way of integrating learned signal-wise features into said matrices without sacrificing their Symmetric Definite Positive (SPD) nature.Results: Through comparison with other State-of-the-Art models within a methodology optimized for class-wise performance, we achieve a level of performance at or beyond various State-of-the-Art models, both in single-dataset and - particularly - multi-dataset experiments.Conclusion: In this article, we prove the capabilities of our SPDTransNet model, particularly its adaptability to multi-dataset tasks, within the context of EEG sleep stage scoring - though it could easily be adapted to any classification task involving timeseries of covariance matrices.
UniMTS: Unified Pre-training for Motion Time Series
Authors: Xiyuan Zhang, Diyan Teng, Ranak Roy Chowdhury, Shuheng Li, Dezhi Hong, Rajesh K. Gupta, Jingbo Shang
Date: 2024-10-18 00:00:00
Tasks: Contrastive Learning, Time Series, Time Series Classification

Motion time series collected from mobile and wearable devices such as smartphones and smartwatches offer significant insights into human behavioral patterns, with wide applications in healthcare, automation, IoT, and AR/XR due to their low-power, always-on nature. However, given security and privacy concerns, building large-scale motion time series datasets remains difficult, preventing the development of pre-trained models for human activity analysis. Typically, existing models are trained and tested on the same dataset, leading to poor generalizability across variations in device location, device mounting orientation and human activity type. In this paper, we introduce UniMTS, the first unified pre-training procedure for motion time series that generalizes across diverse device latent factors and activities. Specifically, we employ a contrastive learning framework that aligns motion time series with text descriptions enriched by large language models. This helps the model learn the semantics of time series to generalize across activities. Given the absence of large-scale motion time series data, we derive and synthesize time series from existing motion skeleton data with all-joint coverage. Spatio-temporal graph networks are utilized to capture the relationships across joints for generalization across different device locations. We further design rotation-invariant augmentation to make the model agnostic to changes in device mounting orientations. Our model shows exceptional generalizability across 18 motion time series classification benchmark datasets, outperforming the best baselines by 340% in the zero-shot setting, 16.3% in the few-shot setting, and 9.2% in the full-shot setting.
BUNDL: Bayesian Uncertainty-aware Deep Learning with Noisy training Labels for Seizure Detection in EEG
Authors: Deeksha M Shama, Archana Venkataraman
Date: 2024-10-17 00:00:00
Tasks: Deep Learning, EEG, Seizure Detection

Deep learning methods are at the forefront of automated epileptic seizure detection and onset zone localization using scalp-EEG. However, the performance of deep learning methods rely heavily on the quality of annotated training datasets. Scalp EEG is susceptible to high noise levels, which in turn leads to imprecise annotations of the seizure timing and characteristics. This label noise presents a significant challenge in model training and generalization. In this paper, we introduce a novel statistical framework that informs a deep learning model of label ambiguity, thereby enhancing the overall seizure detection performance. Our Bayesian UncertaiNty-aware Deep Learning, BUNDL, strategy offers a straightforward and model-agnostic method for training deep neural networks with noisy training labels that does not add any parameters to existing architectures. By integrating domain knowledge into the statistical framework, we derive a novel KL-divergence-based loss function that capitalizes on uncertainty to better learn seizure characteristics from scalp EEG. Additionally, we explore the impact of improved seizure detection on the task of automated onset zone localization. We validate BUNDL using a comprehensive simulated EEG dataset and two publicly available datasets, TUH and CHB-MIT. BUNDL consistently improves the performance of three base models on simulated data under seven types of label noise and three EEG signal-to-noise ratios. Similar improvements were observed in the real-world TUH and CHB-MIT datasets. Finally, we demonstrate that BUNDL improves the accuracy of seizure onset zone localization. BUNDL is specifically designed to address label ambiguities, enabling the training of reliable and trustworthy models for epilepsy evaluation.
Multi-modal Image and Radio Frequency Fusion for Optimizing Vehicle Positioning
Authors: Ouwen Huan, Tao Luo, Mingzhe Chen
Date: 2024-10-15 00:00:00
Tasks: Meta-Learning, Position

In this paper, a multi-modal vehicle positioning framework that jointly localizes vehicles with channel state information (CSI) and images is designed. In particular, we consider an outdoor scenario where each vehicle can communicate with only one BS, and hence, it can upload its estimated CSI to only its associated BS. Each BS is equipped with a set of cameras, such that it can collect a small number of labeled CSI, a large number of unlabeled CSI, and the images taken by cameras. To exploit the unlabeled CSI data and position labels obtained from images, we design an meta-learning based hard expectation-maximization (EM) algorithm. Specifically, since we do not know the corresponding relationship between unlabeled CSI and the multiple vehicle locations in images, we formulate the calculation of the training objective as a minimum matching problem. To reduce the impact of label noises caused by incorrect matching between unlabeled CSI and vehicle locations obtained from images and achieve better convergence, we introduce a weighted loss function on the unlabeled datasets, and study the use of a meta-learning algorithm for computing the weighted loss. Subsequently, the model parameters are updated according to the weighted loss function of unlabeled CSI samples and their matched position labels obtained from images. Simulation results show that the proposed method can reduce the positioning error by up to 61% compared to a baseline that does not use images and uses only CSI fingerprint for vehicle positioning.