Systems and Control · Cross-listed from cs.RO
Crazyflow: An Accurate, GPU-Accelerated, Differentiable Drone Simulator in JAX
Martin Schuck, Marcel P. Rath, Yufei Hua et al. (+3 more)
High-quality, large-scale synthetic data from simulations is becoming a cornerstone for pushing the capabilities of
robot algorithms. While aerial robotics simulators have evolved to support specialized needs such as fidelity, differentiability, and swarms independently, a unified platform that can synthesize data across all these domains is missing. In this work, we propose Crazyflow, a simulator designed to push the limits of aerial-robotics
algorithm development, from model-based to data-driven methods, gradient-based to sampling-based approaches, and single-
agent to multi-
agent systems. Compared to existing state-of-the-art drone simulators, it achieves speeds more than an order of magnitude faster for a single drone and can simulate thousands of swarms of 4000 drones each. Real-world experiments show Crazyflow supports both analytical-gradient-based policy learning, achieving sub-centimeter trajectory tracking accuracy without domain randomization, and sampling-based obstacle avoidance at speeds exceeding half a billion steps per second. Breaking the traditional train-then-deploy paradigm, we show that its unprecedented speed even enables in-flight reinforcement learning; we demonstrate this by throwing a physical drone into the air and training a recovery policy from scratch in 0.38 seconds, successfully stabilizing the drone. Crazyflow supports multiple levels of simulation abstraction, is directly compatible with all open-source Crazyflie models, and enables rapid reconfiguration across custom drone platforms and applications by providing a light-weight system identification pipeline. By pushing accuracy, speed, and differentiability simultaneously, Crazyflow serves as an open-source resource for synthetic data generation, with emerging capabilities for large-scale parallelization for online, in-execution learning and optimization, opening the door to novel
algorithm development.
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All authors Martin Schuck, Marcel P. Rath, Yufei Hua, Abhishek Goudar, SiQi Zhou, Angela P. Schoellig
Audio and Speech Processing · Cross-listed from cs.SD
A Lightweight Slot-Attention Framework for Multi-Instrument Multi-Pitch Estimation
Michael Taenzer
Multi-pitch estimation (MPE) typically predicts which pitches are active in a mixture, but not which instrument or source produced them. This paper investigates a lightweight slot-
attention framework for multi-instrument MPE (MI-MPE), where a mixture CQT is mapped to an unordered set of source-like pitch maps. The model uses permutation-invariant Hungarian matching to avoid fixed output semantics and treats the number of slots as an upper bound on the number of active sources. We further study two modular extensions: a self-supervised timbre encoder that provides training-time targets for slot-level timbre
embeddings, and a polyphony branch that regularizes the pitch density of mixture- and slot-level predictions. Experiments show that Hungarian matching substantially improves instrument family decomposition on URMP. Stem-level prediction remains more challenging: timbre and polyphony supervision improve selected configurations, but do not consistently resolve source assignment. The results suggest that slot-based architectures are a promising direction for source-aware MPE, while highlighting the need to couple auxiliary musical cues to slot identity more carefully.
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Signal Processing
Unitary Spreading for Robust LPI/AJ TRANSEC in CPM Systems
Tucker Hathaway and Daniel Chew
Adversarial feature extraction and blocking jamming threaten tactical CPM links. This paper presents a
unitary spreading-based Transmission Security (TRANSEC) enhancement to obscure physical-layer signatures and improve anti-jamming (AJ) resilience. The enhancement can be used to augment existing techniques. The enhancement preserves the constant-envelope (0 dB PAPR) nature of CPM, ensuring compatibility with high-efficiency tactical amplifiers. Analysis of symbol distributions, spectra, and cyclostationary features demonstrates that the technique masks inherent signatures, preventing modulation classification. We leverage convex optimization to recover symbols under blocking jamming, reducing uncoded BER from 6.25% to 0.04%. Finally, we characterize the engineering trade-offs between security, bandwidth, and BER.
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Signal Processing
FlexLink: Decoupling Control and Data Beams for Next-Generation Wideband Networks
Ish Kumar Jain, Rohith Reddy Vennam and Dinesh Bharadia
The next generation of 6G networks aims to utilize ultra-wideband spectrum and massive
antenna arrays to serve multiple users with both control and data channels at low latency and high efficiency. However, phased arrays at mmWave and mid-bands are fundamentally constrained to a single beam or suffer sharp beamforming loss when split across directions, limiting simultaneous control-data support. In FlexLink, we introduce and prototype a novel delay-phased array architecture that overcomes this limitation by redistributing energy jointly across frequency and space, enabling multiple narrow beams without sacrificing per-beam gain or requiring additional power. We design and prototype FlexLink on a custom 4-7 GHz hardware testbed, demonstrating for the first time that control and data beams can be decoupled in practice, achieving nearly double spectral efficiency compared to conventional phased arrays.
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Signal Processing
Spatially Distributed Task-Oriented Compression for Multi-Emitter Localization and Characterization with Spectral Overlap
H. Nazim Bicer and J. Nicholas Laneman
Radio frequency spectrum awareness requires the ability to detect, localize, and characterize emitters in dense and contested wireless environments. In this work, we propose a task-oriented distributed compression framework for joint multi-emitter localization and characterization using spatially distributed receivers. Each receiver observes a short window of complex IQ samples, converts the observation to a time–frequency representation, and encodes it into a compact latent vector. A central fusion decoder combines the receiver latents to estimate an unordered set of active emitters, including their locations, center-frequency offsets, occupied bandwidths, and waveform families. A permutation-invariant training objective is used to handle the arbitrary ordering of emitters and predictions. Experiments on synthetic multi-emitter scenes with spectral overlap show that even extremely compact receiver-side representations can preserve useful information for emitter counting and waveform-family estimation. However, accurate localization and spectral-parameter regression require larger latent dimensions. Increasing the receiver latent dimension from $d_{\mathrm{rx}}=1$ to $d_{\mathrm{rx}}=16$ provides the largest improvement, while further increasing to $d_{\mathrm{rx}}=64$ gives smaller gains. These results demonstrate the potential of learned task-oriented compression for communication-efficient distributed spectrum awareness.
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Image and Video Processing · Cross-listed from cs.LG
Leaf Spectral Reflectance Prediction Using Multi-Head Attention Neural Networks
Parastoo Farajpoor, Alireza Pourreza, Mohammadreza Narimani et al. (+2 more)
Accurate modeling of leaf spectral reflectance from physiological and biochemical traits is essential for advancing remote sensing applications in plant science and precision agriculture. Widely used radiative transfer models, such as PROSPECT-PRO, rely on generalized trait-reflectance relationships developed from a wide range of species, which may not fully capture the spectral behavior of specific crops like grapevines. In this study, we developed a trait-to-spectra prediction model using a multi-head
attention neural network trained on a grapevine-specific
dataset that includes 16 leaf traits measured across multiple varieties, growth stages, and years. The model was evaluated using stratified 5-fold cross-validation and achieved an average coefficient of determination (R^2) of 0.84 and normalized root mean squared error (NRMSE) of 1.52 percent, demonstrating high accuracy and generalizability. When compared to PROSPECT-PRO in forward mode, the neural network exhibited lower mean absolute error (MAE), especially in the near-infrared (NIR) and shortwave-infrared (SWIR) regions. These results emphasize the importance of species-specific modeling approaches and show that integrating biochemical and structural traits into data-driven architectures can significantly improve spectral prediction. The proposed model provides a robust framework for generating accurate leaf-level reflectance data, with potential applications in canopy trait
retrieval, vineyard monitoring, and remote sensing-driven crop management.
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All authors Parastoo Farajpoor, Alireza Pourreza, Mohammadreza Narimani, Ashraf El-Kereamy, Matthew W. Fidelibus
Signal Processing
Power consumption and spectral efficiency analysis for uplink analog radio-over-fiber
Shehla Amir, Miguel Rodrigo Castellanos and Robert W. Heath Jr
Radio-over-fiber centralizes
radio access networks by using a low-loss optical fiber link between the remote
radio head and the central unit. Analog
radio-over-fiber (A-RoF) transmits RF signals modulated directly onto an optical carrier, avoiding digitization and digital signal processing at the remote
radio head. In this way, A-RoF shifts power-hungry processing from the
antenna to the baseband unit. This paper outlines a mathematical framework to analyze the effect of fiber nonlinearity in an uplink wireless system supported by A-RoF. We model an input/output relationship that incorporates the wireless channel, thermal noise, and impairments encountered in the optical fiber channel: chromatic dispersion, electrical-to-optical conversion loss, amplification noise, and fiber nonlinear interference. We compare A-RoF with DSP-assisted A-RoF and digital
radio receivers. Our results show that A-RoF achieves higher energy efficiency as compared to digital receivers with 8- and 16-bit analog-to-digital converters and DSP-assisted A-RoF. We further characterize the trade-offs among transmit power, nonlinear interference, and spectral efficiency, demonstrating that nonlinear effects fundamentally limit achievable rates. These results identify the linear operating regions where A-RoF is most effective for uplink wireless communication.
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Systems and Control
Hosting Capacity Assessment and Enhancement for Edge Data Centers in Active Distribution Networks
Linhan Fang and Xingpeng Li
With the increasing demand for edge computing and AI-driven workloads, integrating small and medium-sized edge data centers into distribution networks has become increasingly important. This paper investigates the hosting capacity of distribution networks for data center integration and identifies the key physical mechanisms that limit the maximum allowable data center load. The baseline analysis shows that data center hosting capacity varies significantly across candidate buses due to network
topology and electrical distance. Three dominant limiting mechanisms are identified: current-constrained locations, voltage-constrained locations, and mixed-constrained locations where both current loading and voltage deviation jointly affect hosting capacity. To increase the hosting capacity, this study evaluates multiple flexible resources, including battery energy storage systems (BESS), dispatchable distributed generators (DDG), and static synchronous compensators (STATCOM). Numerical results demonstrate that these resources provide complementary benefits through active power support, sustained local generation, and reactive power compensation, effectively expanding data center hosting capacity in distribution systems.
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Systems and Control · Cross-listed from cs.RO
Autopilot-Preserving Residual Q-Learning with HJB-Inspired Finite-Action Risk Filtering for Fixed-Wing UAV Command Supervision
Mehmet Iscan and Batuhan Temiz
A fixed-wing
UAV must hold airspeed, altitude, and heading references under wind, gusts, and
turbulence, channels coupled so that correcting one can degrade another. Classical autopilots stabilize the airframe well but adapt poorly when a hard crosswind meets an aggressive turn, while reinforcement-learning (RL) policies acting directly on the surfaces concentrate exploration risk at the actuator interface. We place a learned supervisor above an unchanged autopilot rather than inside it: it selects a residual from a finite, bounded action set on the commanded airspeed, altitude, and heading; the modified reference is projected into an admissible command envelope before reaching the autopilot, which stays the only actuator-facing controller. What is new is how the residual is chosen. HJB residual scores candidates with a semi-discrete value-iteration critic in the spirit of the Hamilton-Jacobi-Bellman (HJB) equation, ranks them by a no-op-relative
Hamiltonian advantage, and filters them through a control-Lyapunov- and control-barrier-inspired finite-action shield that always keeps a no-op fallback. On a shared 12-state runtime holding the plant, autopilot, and actuator model fixed, so the comparison is at the package level, HJB residual lowers mean RMS path-tracking error to 44.809 m, against 338.617 m for the baseline autopilot and 88.809 m for a tabular-Q residual, an 86.77% reduction over the baseline and 49.54% over Q-learning. The gain concentrates where the baseline fails worst and comes with a measured rise in airspeed error, so no method dominates every metric. We present this autopilot-preserving residual command-supervision design and
benchmark with its trade-offs reported intact.
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Signal Processing
Adaptive UAV Communications for URLLC: From Preplanned Designs to Real-Time Intelligence
Asim Ihsan, Muhammad Asif, Ali Arshad Nasir et al. (+2 more)
Unmanned aerial vehicles (
UAVs) are emerging as a key enabler of next-generation wireless networks, particularly for applications that require ultra-reliable and low-latency communication (URLLC), such as emergency response, industrial automation, and autonomous systems. In these scenarios, maintaining reliable connectivity under strict transmission time constraints is challenging due to dynamic environments, mobility, and limited onboard energy. In particular, communication performance and energy are closely coupled with
UAV movement, making trajectory design a critical component of system operation. Most existing approaches rely on offline joint communication and trajectory optimization, where the
UAV trajectory and communication parameters are optimized prior to execution based on assumed system information. Although effective under ideal assumptions, such designs cannot adapt to real-time variations in user demand, channel conditions, or environmental disturbances, which are particularly critical in URLLC settings. To address these challenges, this article investigates model predictive control (MPC) as an adaptive framework for
UAV-enabled communications. Using a receding-horizon strategy, MPC enables the
UAV to continuously update its trajectory based on real-time information, improving reliability and robustness in dynamic environments. Representative application scenarios are discussed to highlight the role of MPC in
UAV-enabled URLLC systems. Furthermore, a case study is presented to illustrate key design trade-offs and performance insights under finite blocklength-based URLLC transmission, followed by a discussion on open challenges and future research directions for practical and scalable MPC-enabled
UAV communication systems.
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All authors Asim Ihsan, Muhammad Asif, Ali Arshad Nasir, Wali Ullah Khan, Khaled M. Rabie
Systems and Control
A Koopman Set-Membership Approach for Nonlinear Data-Driven Control with Stability Guarantees
Yifan Xie, Zuxun Xiong, Julian Berberich et al. (+2 more)
This paper proposes a data-driven controller design method for unknown nonlinear systems based on a Koopman bilinear realization. Using Koopman operator theory, the nonlinear system can be represented as a bilinear discrete-time system with a residual error term. The residual error is proportionally bounded by the norm of the lifted state and input, while the system
matrices of the bilinear model are unknown. Assuming that bounds on the residual error are available, the unknown system
matrices are characterized via a set-membership representation using the collected input-state data pairs of the nonlinear system. A data-driven controller design method is proposed to ensure stability for all bilinear systems within this set-membership description and for all admissible residual errors. More specifically, we design a rational state-feedback controller that stabilizes the bilinear model with residual error and, consequently, the original nonlinear system, by solving a sum-of-squares (SOS) program. The effectiveness of the proposed approach is demonstrated through numerical examples.
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All authors Yifan Xie, Zuxun Xiong, Julian Berberich, Antonis Papachristodoulou, Frank Allgöwer
Systems and Control · Cross-listed from cs.LG
All Models are Wrong, Knowing Where is Useful: On Model Uncertainty in Reinforcement Learning
Bernd Frauenknecht, Devdutt Subhasish, Artur Eisele et al. (+2 more)
Model-based reinforcement learning (MBRL) infers information about the environment from a learned dynamics model and bears the potential to address open problems such as data efficient and safe learning in robotics. However, inaccuracies of the learned dynamics model are typically exploited by the
agent, substantially hampering the capabilities of MBRL methods. We present a framework for dealing with inaccuracies of probabilistic models through targeted handling of uncertainty that effectively mitigates model exploitation. We present recent successes in learning directly on hardware and safe exploration, and discuss future directions for uncertainty-aware MBRL.
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All authors Bernd Frauenknecht, Devdutt Subhasish, Artur Eisele, Friedrich Solowjow, Sebastian Trimpe
Signal Processing · Cross-listed from cs.IT
Low-Subpacketization MIMO Coded Caching with Flexible Stream Allocation
Mohammad NaseriTehrani, MohammadJavad Salehi and Antti Tölli
Subpacketization remains a major obstacle to the practical deployment of coded caching (CC) in multi-
antenna wireless networks. In this paper, we propose a low-complexity multiple-input multiple-output (
MIMO) CC scheme that enables flexible delivery rate adaptation while substantially reducing subpacketization requirements. The proposed design employs a virtual broadcast-channel decomposition to align cache-profile placement with flexible
MIMO stream elevation which extends the shared-cache model to multi-
antenna receivers. This enables flexible selection of feasible user and stream configurations, thereby providing explicit control over the spatial multiplexing gain under linear decodability constraints. Analytical results show that the proposed framework can asymptotically approach the best-known achievable degrees of freedom (DoF) under linear decodability constraints while requiring orders-of-magnitude lower subpacketization than existing schemes. Numerical evaluations further demonstrate that this flexibility yields notable throughput improvements at practical signal-to-noise ratios.
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Signal Processing
A Communication-Centric 6G-LLM Architecture for Scalable Tactical Autonomous Defense Vehicle Networks
Kiran Khurshid, Shumaila Javaid and Nasir Saeed
The integration of Artificial Intelligence (AI) and emerging 6G networks introduces new opportunities for scalable coordination in tactical autonomous vehicle systems. This paper proposes a communication-centric hierarchical architecture for Tactical Autonomous Defense Vehicle Networks (TADVNs) that models the integration of edge-assisted Large
Language Model (LLM)
reasoning with 6G-enabled connectivity and semantic communication. The framework is designed to improve coordination efficiency, reduce communication overhead, and enhance latency resilience under increasing fleet-scale operation. Unlike conventional task-specific AI pipelines that rely on structured feature processing and rule-based coordination, the proposed approach incorporates semantic abstraction and context-aware decision support within a layered edge-cloud communication architecture. We evaluate communication and coordination performance via Monte Carlo simulations across fleet sizes of 5-30 vehicles under contested network conditions. Results indicate that at a 30-vehicle scale, the 6G-LLM configuration achieves 75.2% latency reduction (29.1 ms vs. 117.5 ms), a 68.7 percentage point increase in mission success rate (82.9% vs. 14.2%), and an 88.6% reduction in communication overhead compared to a 5G-based conventional AI baseline. These findings demonstrate measurable benefits in coordination and communication when semantic
reasoning is combined with low-latency 6G connectivity.
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Image and Video Processing
ResNet-34 with Lightweight Decoder for Accurate and Efficient Segmentation of Fetal Brain MRI
Ashiqur Rahman, Muhammad E. H. Chowdhury, Md. Abu Sayed et al. (+3 more)
Accurate
segmentation of fetal
brain tissues in
Magnetic Resonance Imaging (MRI) is critical for early diagnosis of congenital abnormalities and improving prenatal care. However, the task remains difficult because of fetal motion, low tissue contrast, and major anatomical variability throughout gestational ages, particularly in segmenting complex structures such as white matter, gray matter, lateral ventricles, deep gray matter, extra-cerebrospinal fluid, cerebellum, and brainstem. As a solution to these difficulties, this research introduces a novel deep learning model that combines a ResNet-34 encoder with a lightweight decoder leveraging multi-layer perceptron (MLP) modules for adaptive feature refinement. This design specifically enhances the model's ability to preserve anatomical boundaries and mitigate
segmentation errors caused by motion artifacts and intensity inhomogeneities. Computational efficiency is achieved by reducing parameter count, employing bilinear upsampling instead of transposed convolutions, and optimizing the decoder for speed without sacrificing accuracy. Trained and validated on the FeTA 2021
dataset using 5-fold cross-validation, the proposed model outperforms baseline architectures such as UNet, UNet++, DeepLabV3, and DeepLabV3+, achieving an average Accuracy of 97.37% with a mean Dice Similarity Coefficient (DSC) of 90.33%, mean Intersection over Union (IoU) of 86.93%, and Precision of 90.83%. Additionally, its fast inference time and reduced computational load make it well-suited for integration into real-time clinical workflows.
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All authors Ashiqur Rahman, Muhammad E. H. Chowdhury, Md. Abu Sayed, Md. Sharjis Ibne Wadud, Abu Naser Md. Arafat, Mehedi Hasan Prince
Systems and Control · Cross-listed from cs.IT
Toward Reliable Semantic Communication: Beyond Average Performance
Boyuan Li, Mingze Gong, Shuoyao Wang et al. (+3 more)
Semantic communication has emerged as a promising paradigm for improving transmission efficiency by conveying task-relevant semantics rather than raw data. Although recent studies have achieved notable gains in communication efficiency and average task performance, reliability remains a fundamental bottleneck in dynamic and uncertain environments. In particular, most existing designs are still optimized mainly for average-case behavior, while lower-tail performance under adverse transmission conditions remains insufficiently understood and inadequately protected. In this article, we present a unified perspective on reliable semantic communication beyond average performance. We first review three reliability-oriented design categories: channel-aware adaptation, robustness-oriented codec design, and hybrid automatic repeat request (HARQ)-based retransmission. We show that these approaches address reliability from complementary perspectives, but each still has inherent limitations. Motivated by these observations, we discuss two solution directions: robust adaptive semantic communication under imperfect CSI, and joint source-channel-check coding with adaptive retransmission for sample-level reliability enhancement. Finally, we outline several future research directions, including the joint design of robustness and retransmission, reliability metrics beyond averages, and compatibility with existing digital wireless networks.
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All authors Boyuan Li, Mingze Gong, Shuoyao Wang, Suzhi Bi, Jia Yan, Ying-Jun Angela Zhang
Systems and Control · Cross-listed from cs.RO
DeepIPCv3: Event-Aware Multi-Modal Sensor Fusion for Sudden Pedestrian Crossing Avoidance
Oskar Natan, Andi Dharmawan, Aufaclav Zatu Kusuma Frisky et al. (+2 more)
Current end-to-end autonomous driving systems predominantly rely on frame-based sensors, which suffer from inherent perception latency and motion blur during highly dynamic encounters, specifically sudden pedestrian crossings. To address this critical safety vulnerability, we propose DeepIPCv3, a novel multi-modal autonomous
navigation framework that synergizes the dense 3D spatial geometry of
LiDAR point clouds with the microsecond-level asynchronous event streams of a Dynamic
Vision Sensor (DVS). We introduce a
Transformer-inspired cross-modal
attention mechanism to dynamically correlate these distinct modalities, allowing the network to instantaneously prioritize high-speed dynamic updates without sacrificing structural scene awareness. The fused latent representations are then mapped to safe local waypoints and executable control commands via a hybrid policy network that blends heuristic trajectory tracking with direct neural predictions. Due to the severe physical risks associated with live testing of these sudden crossing scenarios, the framework is rigorously evaluated offline using a custom multi-modal
dataset collected across both well-illuminated noon and challenging evening conditions. Extensive comparative and ablation studies demonstrate that DeepIPCv3 achieves state-of-the-art predictive performance. By effectively eliminating exposure failures and motion blur, the proposed
LiDAR and DVS fusion yields the lowest trajectory and control command errors, enabling highly reactive, mathematically bounded evasive maneuvers regardless of ambient illumination. To support future research, we will release the codes to our GitHub repo at https://github.com/oskarnatan/DeepIPCv3.
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All authors Oskar Natan, Andi Dharmawan, Aufaclav Zatu Kusuma Frisky, Jazi Eko Istiyanto, Jun Miura
Systems and Control
Regulating EV Charging Markets for Fairness: Incentives for Pricing and Capacity Decisions
Ruiting Wang, Kita Hu, Yitong Yu et al. (+1 more)
The transition to electric mobility calls for charging infrastructure that is both efficient and socially equitable. This paper examines
fairness in electric vehicle (EV) charging station pricing and capacity through a game-theoretic perspective. We model a non-cooperative
market in which competing charging service providers set prices and capacities while customers choose stations based on generalized cost, leading to a
market equilibrium. We then
benchmark this decentralized outcome against an idealized planner solution that jointly optimizes efficiency and equity. To align
market outcomes with socially desirable goals, we design targeted incentives that guide operators toward more fair charger placement. Case studies demonstrate that unregulated competition tends to exacerbate disparities in charger access across demographic groups, whereas carefully calibrated incentives can reduce inequities without significant efficiency loss. The framework provides insights for policymakers on reconciling free-
market dynamics with the broader societal goals of
fairness in electrified mobility systems.
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All authors Ruiting Wang, Kita Hu, Yitong Yu, Scott Moura
Audio and Speech Processing · Cross-listed from q-bio.NC
A 1000-hour EEG-EMG-audio dataset of Japanese speech production
Motoshige Sato, Ilya Horiguchi, Masakazu Inoue et al. (+6 more)
We present a
multimodal dataset of 1020 hours of simultaneously recorded scalp electroencephalography (
EEG), facial electromyography (EMG), and
speech audio from three healthy native Japanese speakers during open-vocabulary overt
speech. Recordings were acquired with three
EEG systems-an ultra-high-density system (g.Pangolin) and two cap-type systems (g.SCARABEO and eegosports), spanning 62-128 channels-across many sessions over several months. Each session provides time-synchronized
EEG, facial EMG, and audio, together with
speech-event annotations and transcriptions. Although collected with
speech decoding as a primary motivation, the
dataset also supports work on
multimodal signal processing, artifact modeling, longitudinal and cross-device adaptation, and
EEG representation learning. Technical validation included power spectral density and event-related potential analyses across participants, devices, and tasks, which showed the expected 1/f spectral profile, task-related alpha-band attenuation, and time-locked evoked responses. The
dataset is released in
Brain Imaging Data Structure (BIDS) format via OpenNeuro under a CC0 waiver to support both
speech-related and broader
EEG research.
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All authors Motoshige Sato, Ilya Horiguchi, Masakazu Inoue, Kenichi Tomeoka, Eri Hatakeyama, Yuya Kita, Atsushi Yamamoto, Ippei Fujisawa, Shuntaro Sasai
Signal Processing
Beyond the RF Paradigm: Rydberg Atomic Receivers for Next-Generation IoT
Qihao Peng, Qu Luo, Dongnan Xia et al. (+11 more)
Next-generation Internet-of-Things (IoT) is evolving toward a ubiquitous, ultra-low-power, and multi-band heterogeneous networking paradigm that seamlessly integrates terrestrial, non-terrestrial, and ambient devices. This
vision places unprecedented demands on conventional
radio frequency (RF) receivers, whose fundamental bottlenecks in sensitivity, power consumption, coverage, and multi-band operation are rooted in the RF
antenna. To tackle these issues, we show that the
quantum properties of Rydberg atomic
quantum receivers (RAQRs), including ultra-high sensitivity, broad frequency agility, and diverse reception modalities, provide a physically distinct receiver-side path that replaces the conventional
antenna-and-low-noise-amplifier chain. Using LoRa, narrowband IoT, and ambient IoT as case studies, this article shows that RAQRs deliver significant gains in weak-uplink, low-power, and battery-free regimes. A
stochastic-geometry analysis in cellular and
cell-free architectures then maps these device-level gains onto network coverage, where the RAQR retains roughly a 4 dB half-coverage advantage over the RF receiver in sparse deployments at \(\lambda \sim 10^{-5}~{\mathrm m}^{-2}\), with the gain eroded as device density grows. The open challenges are presented to stand between current RAQR prototypes and deployable IoT infrastructure.
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All authors Qihao Peng, Qu Luo, Dongnan Xia, Zhehua Zhang, Zeyan Zhang, Jizhou Wu, Kezhi Wang, Cunhua Pan, Maged Elkashlan, Pei Xiao, Derrick Wing Kwan Ng, Trung Q. Duong, George K. Karagiannidis, Jiangzhou Wang
Image and Video Processing
RFDT-Channel: RGB-LiDAR-Based RF Digital Twin Scene Construction for 28 GHz Indoor Ray-Tracing Channel Simulation
Chengyang Yao, Cunhua Pan, Jiaming Zeng et al. (+5 more)
Real-scene indoor millimeter-wave simulation requires efficient modeling of
radio frequency (RF)-computable geometry and electromagnetic material properties. To address the low efficiency of manual scene modeling, the limited RF adaptability of visually reconstructed meshes, and the lack of material binding in 28 GHz ray-tracing simulation, RFDT-Channel is developed as an RF digital twin scene construction workflow based on red-green-blue (RGB) images and light detection and ranging (
LiDAR) point clouds. Indoor
videos and point clouds are collected by a Jetson Orin platform with
LiDAR and GMSL cameras. An initial triangular mesh is generated through COLMAP, 3D Gaussian Splatting, and SuGaR. The
LiDAR point cloud then provides
geometric and scale references for RF-oriented regularization in Blender, including
alignment, wall solidification, door/window opening construction, and
topology repair. OpenScene semantic
segmentation maps major indoor structures to concrete, glass, wood, and metal materials, and Sionna RT performs 28 GHz ray tracing. Under a fixed transmitter-receiver deployment, the generated channel impulse response (CIR), channel frequency response (CFR), and
Radio Map results show that material binding mainly changes weak reflection, transmission, and scattering paths, reducing the number of effective paths from about 742 to about 52 while keeping the dominant path amplitude nearly unchanged.
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All authors Chengyang Yao, Cunhua Pan, Jiaming Zeng, Yuquan Sun, Haoyang Weng, Haojian Wang, Hong Ren, Jiangzhou Wang
Signal Processing · Cross-listed from cs.LG
Beyond Sinusoids: A Morlet Wavelet Framework for Transformer Positional Encoding
Athanasios Zeris
Standard positional encodings for
transformers - sinusoidal and rotary (RoPE) - treat every position as equally local: they encode where a
token is, but not how far its positional influence should extend. We propose that the Morlet wavelet, which simultaneously minimises uncertainty in position and frequency, is the natural basis for positional encoding, and introduce Morlet Positional Encoding (MoPE): each
embedding dimension learns its own frequency and locality bandwidth from data. The main theoretical result is a unification: sinusoidal PE and the RoPE correlation kernel both emerge as limiting cases of MoPE when locality is switched off (sigma_i -> infinity). The phase of MoPE recovers the RoPE rotation angle exactly; the amplitude adds a learned Gaussian locality kernel that standard encodings lack. Empirically, MoPE combined with Energy-Gated
Attention achieves +0.119 improvement over standard
attention on TinyShakespeare, outperforming either component alone. Analysis of the learned parameters reveals that all 128 frequency-bandwidth pairs converge to the wavelet admissibility boundary - an empirical observation consistent with a companion result on energy gating, suggesting a reproducible property of character-level
language signals that warrants further investigation.
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Signal Processing
Online Censoring-Based Widely Linear Total Least lncosh Method for Improved Power System Frequency Estimation
Haiquan Zhao, Kaleab Derbew Abebe and Yi Peng
Recently, under the presumption of a noise-free input, the augmented complex least lncosh (ACLlncosh) method was introduced for a power system frequency estimate and showed robust performance when impulsive noise polluted the output signal. However, in practical terms, noise often contaminates input signals, which drastically reduces the efficiency of the ACLlncosh method. To enhance robustness against noisy input-output while maintaining resilience to impulsive noise in the output signal, this paper proposed an online censoring-based widely linear total least lncosh (OC-WL-TLlnC) method. This method improves performance under both balanced and unbalanced settings by filtering out less valuable data via online censoring, hence reducing the computing burden. Furthermore, a variable parameter approach is incorporated to accelerate convergence and improve steady-state accuracy, thereby ensuring adaptability to dynamic power system conditions. The proposed methods significantly enhance frequency estimate performance by addressing the constraints of current techniques and offering a computationally efficient, noise-resilient solution for real-time power system monitoring.
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Signal Processing
SweetFruit: A Two-Stage Mobile Sensing System for Real-Time Fruit Sugar Estimation
Mark Cardamis, Yanxiang Wang, Chun Tung Chou et al. (+1 more)
Accurate prediction of fruit sugar content is essential for quality control and
market valuation in agriculture. Conventional measurement techniques rely on destructive, time-consuming processes (e.g., juicing and refractometry) or direct contact instruments, which hinder high-throughput operations. This paper introduces SweetFruit, a mobile two-stage system that leverages low-cost sensors to estimate fruit sugar content without contact. In Stage 1, we implement a lightweight 3D deep learning model (SF-PointNet) that uses point clouds from a Time-of-Flight (ToF) depth camera to classify fruit as high or low sugar. In Stage 2, a regression network (SF-Net) predicts the fruit's Brix value using measurements from a compact 18-channel near-infrared (NIR) spectrometer. The system uses simple off-the-shelf sensors (AS7265x NIR and Arducam ToF) with efficient processing pipelines for real-time execution on embedded platforms. Experiments on green 'Granny Smith' apples and strawberries demonstrate the system's effectiveness. Stage 1 achieves over 90% classification accuracy, enabling rapid prescreening, while Stage 2 delivers precise sugar estimates, with a root mean square error (RMSE) of 0.57 Brix, reducing error by 22% compared to using NIR sensing alone. SweetFruit offers a scalable, field-ready solution for rapid fruit quality screening, showcasing the benefits of task-specific
multimodal sensing in mobile agricultural applications.
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All authors Mark Cardamis, Yanxiang Wang, Chun Tung Chou, Wen Hu
Signal Processing
RAG-driven Multi-Agent LLM Framework with Task Decomposition for Beyond 5G Auto-Configuration
İrşat Emin Sar{\i}daş, Onur Salan, Ali Görçin et al. (+2 more)
While Large
Language Models (LLMs) offer a promising path toward intent-driven network management by translating natural
language human intents into machine-readable configurations, they often suffer from
hallucinations and structural inconsistencies in multi-step and complex tasks. To address these challenges, this paper proposes a
retrieval-augmented and task decomposition-based multi-
agent LLM framework for Beyond 5G network auto-configuration. The framework employs a semantic
retrieval-augmented generation pipeline to ensure that its outputs are aligned with technical standards and vendor-specific manuals. Furthermore, it introduces a modular architecture for configuration generation, closed-loop configuration verification, and network deployment, in which complex tasks are decomposed into smaller sub-tasks handled by specialized
agents. In this architecture, hallucinated configuration parameters are identified by the configuration verifier
agent and corrected through low computational segment-level regeneration. The performance evaluation experiments with the OpenAirInterface emulator demonstrate that the proposed task decomposition-based configuration and verification approach improves the average success rate by 22.7% over monolithic methods, achieving 94.4% success in network configuration.
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All authors İrşat Emin Sar{\i}daş, Onur Salan, Ali Görçin, Ibrahim Hokelek, Hakan Ali Ç{\i}rpan
Systems and Control
Efficient Numerical Modeling of Near-Field Diffraction in ORIS-Assisted Free-Space Optical Links
Tuan A. Hoang, Phuc V. Trinh, Shinya Sugiura et al. (+3 more)
This paper investigates near-field propagation in optical reconfigurable intelligent surface (ORIS)-assisted free-space optical (FSO) communication systems. Unlike conventional far-field scenarios, near-field propagation involves complex diffraction effects that hinder tractable closed-form analysis. To address this issue, a numerical framework for evaluating the optical field distribution of ORIS-assisted FSO links is proposed. Specifically, two numerical approaches are considered: direct Riemann-sum evaluation and a fast
Fourier transform (FFT)-based method. Although the Riemann sum approach provides accurate field estimation, it incurs extremely high computational complexity due to the fine spatial discretization of the ORIS surface required at optical wavelengths. To improve computational efficiency, the optical-field calculation is reformulated as a convolution in the spatial-frequency domain, enabling efficient FFT-based propagation analysis. Simulation results demonstrate that the proposed FFT-based method achieves accuracy comparable to that of the Riemann-sum approach while significantly reducing computational complexity.
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All authors Tuan A. Hoang, Phuc V. Trinh, Shinya Sugiura, Chuyen T. Nguyen, Susumu Ishihara, Thanh V. Pham
Systems and Control
Data-Driven Min-Max MPC with Integral Quadratic Constraints
Yifan Xie, Julian Berberich and Frank Allgöwer
Data-driven control of nonlinear systems with rigorous guarantees is a challenging control problem. Integral quadratic constraints (IQCs) provide a powerful framework for modeling nonlinearities. This paper presents a data-driven min-max model predictive control (MPC) synthesis method for unknown systems subject to (nonlinear) uncertainties using the IQC framework. The unknown system
matrices are characterized by a set-membership representation using the input-state data and the knowledge of the IQCs. We derive two semidefinite programs (SDPs) that minimize an upper bound on the worst-case cost over all possible system dynamics and uncertainties. By iteratively solving these SDPs, the proposed state-feedback control law is obtained. We further prove that the resulting closed-loop system is exponentially stable and satisfies the input and state constraints. A numerical example demonstrates the validity of the proposed method.
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Signal Processing
Experimental Demonstration of a Real Time Wideband OFDM Generation in Sub-THz
Eray Güven, Nesrine Benchoubane and Güneş Karabulut Kurt
Sub-terahertz (Sub-THz) wireless communications and their potential applications continue to attract significant
attention and foster debate on the usage of their unused frequency bands to relieve existing spectrum congestion. However, for these next-generation networks, experimental research is limited by the lack of flexible, real-time testbeds. This study presents a real-time, multi-
radio-frequency(RF) channel, cascaded software-defined
radio (SDR)-based Orthogonal Frequency-Division Multiplexing (OFDM) transmission platform achieving an aggregate sampling rate of 2 x 3.84 GSPS and approximately 1.1 GHz of instantaneous bandwidth, targeting sub-THz and THz SDR testbeds. The digital transmitter architecture, including the OFDM signal processing chain and instrumentation workflow, is described in detail. A comparative case study between a conventional sub-6 GHz implementation and a 180 GHz configuration is conducted, evaluating phase noise, spectral occupancy, received average and peak power. The direct impact of sub-THz bandpass filtering, necessitated by harmonic-mixer-based upconversion, is also experimentally analyzed. Measurement results show conversion and filtering losses of up to 24.1 dB, while the system exhibits stationary phase noise levels on the order of -60 dBc/Hz, demonstrating the feasibility and limitations of real-time wideband OFDM transmission at 180 GHz. Beyond immediate current capabilities, the platform builds a foundation for the scalable integration of multiple transmitters and receivers, which is essential for the implementation, conformance, and testing of emerging sub-THz communication systems.
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Signal Processing
Artificial-Intelligence-Assisted Multi-Modal Terahertz Sensing and Environment Reconstruction
Yejian Lyu, Zitong Fang, Zhiqiang Yuan et al. (+2 more)
Multi-modal sensing is an important enabler for future environment-aware wireless systems, since a single sensing modality is generally insufficient to provide accurate metric geometry, material awareness, and semantic interpretability in complex environments. This paper presents a measurement-based multi-modal THz sensing and
vision framework for indoor environment reconstruction. A three-dimensional monostatic THz channel sounding system operating at 290-310 GHz is integrated with an omnidirectional fisheye camera to acquire
radio-frequency and visual observations from a common sensing viewpoint. From the measured THz data, a signal processing pipeline extracts multipath components and infers geometryand material-consistent structural primitives through trajectory tracking-assisted parameter estimation, graph-based structure discovery, planar reconstruction, and reflection-loss analysis. In parallel, AI-based visual perception modules extract object-level semantic masks and depth priors from panoramic images. To associate these heterogeneous representations, an agentic-AI-based task-driven THz-
agent module is developed to select appropriate integration tools according to the attributes of the modality-specific outputs. Through angular
alignment and consistency analysis, THz-derived metric geometry and material information are associated with
vision-derived semantic regions and depth priors, enabling geometry-consistent and semantically interpretable environment reconstruction directly from measurements. Experimental validation in the indoor L-shaped hallway demonstrates that the proposed framework reconstructs dominant structural elements with centimeter-level accuracy while identifying semantic categories and material attributes of representative indoor objects.
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All authors Yejian Lyu, Zitong Fang, Zhiqiang Yuan, Henk Wymeersch, Chong Han
Signal Processing
IO Pad Integrity in Energy-Efficient Neuromorphic Chips
Arfan Ghani
Neuromorphic computing relies on low-power, high-reliability hardware, yet the integrity of input/output pads (IOPADs) remains an underexplored factor affecting system performance. This chapter examines the role of IOPAD integrity in neuromorphic VLSI design and connects algorithmic development with practical hardware implementation. While much
attention has been given to spiking neural networks (SNNs) and ultra-low-power core logic, the electrical and functional robustness of the I/O interface is equally critical for ensuring signal fidelity and minimizing energy consumption. We review the structure and function of IOPADs, outline their influence on power, performance, and reliability, and discuss design trade-offs involving pad libraries, pad ring architectures, and bonding strategies. The chapter also introduces the fundamentals of SNNs and summarizes the digital hardware design flow from behavioral description to physical layout. Physical implementation considerations are highlighted using the SkyWater 130 nm CMOS process as a practical platform for neuromorphic prototyping. Real-world examples illustrate how early-stage I/O planning can prevent redesign, reduce yield loss, and improve overall system efficiency. This work emphasizes that IOPAD integrity is a key enabler of scalable, energy-efficient neuromorphic systems.
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