Signal Processing
Graph Learning for Cross-Subject, Cross-Population EEG Emotion Decoding and Model-Derived Spatial-Spectral Neural Signatures
Dongyi He, Bin Jiang, Xiangkai Wang et al. (+4 more)
Cross subject emotion decoding from electroencephalography
EEG requires representations that accommodate individual variability while preserving spatial spectral structure for interpretation. This study introduces EmoDiPyraTrans, a differential graph
Transformer that integrates adaptive graph recurrence, differential
attention, pyramid fusion and distribution regularization over sequential relative power spectral density graphs. Across SEED, FACED, MAHNOB HCI, DEAP and DREAMER, the model achieved the highest participant mean accuracy and positive class F1 among the evaluated methods, with accuracy and F1 both reaching 0.928 on SEED. On DEP
EEG, positive versus neutral accuracy reached 0.802 within healthy controls and 0.704 within participants with depression, compared with 0.591 under healthy to depression transfer and 0.581 with mixed population development. Complementary SEED analyses identified distributed spatial weighting and an alpha centred spectral preference, while configurations averaging six channels retained near full performance. These findings link generalization assessment with model derived candidate signatures to support interpretable
EEG emotion decoding, with code available at https://github.com/hdy6438/EmoDiPyraTrans.
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All authors Dongyi He, Bin Jiang, Xiangkai Wang, Yun Zhao, Hongjie Yan, Wai Ting Siok, Nizhuan Wang
Audio and Speech Processing · Cross-listed from cs.LG
Machine Unlearning for Speech Question Answering in Large Audio-Language Models
Zhe Liu
Large Audio-
Language Models (LALMs) have recently shown strong capabilities in
speech understanding and question answering (QA), but they also inherit
privacy risks from large-scale training data, including the unintended memorization of sensitive information. In this work, we study machine unlearning for
speech QA in LALMs, a setting that is more challenging than prior work on text-based Large
Language Models (LLMs) or Automatic
Speech Recognition (ASR) due to the tight coupling between acoustic perception and factual knowledge. We present and evaluate multiple unlearning strategies, including gradient ascent, task arithmetic, and
alignment-based fine-tuning methods that enforce safe refusal responses, to remove private knowledge while still preserving performance on core capabilities. Through extensive experiments on
speech QA
datasets, we show that these unlearning methods can reduce the
privacy leakage rate by up to 80% while maintaining near-neutral performance on non-private
speech QA and general
speech understanding
benchmarks.
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Signal Processing
Quadratic Unconstrained Binary Optimization for Sparse Magnetoencephalography Source Localization
Arim Ryou and Kiwoong Kim
Magnetoencephalography (MEG) source localization is an ill-posed inverse problem because distinct cortical source configurations can produce similar sensor-level fields. We formulate sparse multi-source localization as a quadratic unconstrained binary optimization (QUBO) problem combined with residual-aware candidate screening. Candidate source-location groups are generated from the sensor-space residual, fixed sensor-space templates are estimated for the resulting candidates, and active templates are jointly selected using data-fit, pairwise template interactions, and soft-cardinality terms. We evaluate the method using classical simulated annealing in controlled synthetic MEG simulations, primarily under a two-source condition, and compare it with MNE, dSPM, MxNE, LCMV, and RAP-MUSIC. Across 100 main-
benchmark trials, QUBO achieved a mean cardinality-aware localization error of 8.45 mm, compared with 22.35 mm for MxNE, the best-performing baseline according to this metric, corresponding to a 62.2% reduction. The composite metric adds a 50 mm penalty per unit of source-count mismatch before normalization by the true source count. Because MxNE returned only one source in 35 trials, the reported reduction reflects both spatial localization and source-count performance. In separate sensitivity experiments, QUBO remained competitive across the tested sensor-noise and source-count conditions, although RAP-MUSIC performed comparably to or better than QUBO in some low-noise and three-source settings. The present experiments use classical simulated annealing and do not evaluate
quantum hardware or claim
quantum advantage. The resulting binary quadratic objective admits a direct Ising representation, enabling future evaluation on
quantum-annealing and hybrid backends.
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Signal Processing
gmsEDA: Decomposition of Electrodermal Activity Signals Using Matrix Separation
Xuemei Chen, David MacQueen, Wendy Donlin Washington et al. (+4 more)
Electrodermal activity (EDA) signals, which reflect sympathetic nervous system arousal through changes in skin conductance, are widely used in psychological and behavioral research. Decomposing an observed EDA signal into its slowly varying tonic baseline and stimulus-driven phasic component is an important preprocessing step; however, existing methods process signals in isolation and remain highly sensitive to noise and motion artifacts. This work introduces gmsEDA, a new decomposition method based on generalized
matrix separation whose model is designed to cope with noise and motion artifacts. Our method analyzes multiple recordings jointly rather than one at a time, taking advantage of patterns shared across signals to produce more accurate and robust results. Numerical experiments on both simulated and real data shows that this approach outperforms existing standard tools.
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All authors Xuemei Chen, David MacQueen, Wendy Donlin Washington, Mark Lammers, Owen Deen, Sean Carey, Margot Ledford
Audio and Speech Processing
VoiceChat-TTS: A Low-Latency Continuous Speech Synthesis Model for Interactive Agents
Edresson Casanova, Jaehyeon Kim, Mariana Graterol Fuenmayor et al. (+17 more)
Spoken dialogue is a natural form of human–computer interaction, yet most
speech language models remain limited to turn-based operation and lack real-time adaptability, such as user barge-in. Recent duplex
speech-to-
speech and
speech-to-text models reduce latency by replacing multi-stage pipelines, but often compromise
speech quality because accurate ASR, interruption handling, and high-fidelity synthesis must be optimized jointly. We propose VoiceChat-TTS, a low-latency, continuous, and streamable text-to-
speech model for interactive
agents. VoiceChat-TTS is driven directly by LLM text-
token streams, supports explicit interruption via control
tokens, and produces silence when no textual input is available. The model enables always-on, responsive
speech generation while preserving modularity and high
speech quality, and it supports mid-utterance interruptions without resetting the KV cache.
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All authors Edresson Casanova, Jaehyeon Kim, Mariana Graterol Fuenmayor, Shehzeen Hussain, Viacheslav Klimkov, Valentin Mendelev, Mikyas Desta, Paarth Neekhara, Piotr Zelasko, Chen Chen, Elena Rastorgueva, Ke Hu, Ankita Pasad, Xuesong Yang, Aya Alja'fari, Rajarshi Roy, Rohan Badlani, Jason Roche, Jason Li, Zhehuai Chen
Systems and Control
Hierarchical Sensor-Spoofing Defence Framework for Networked DC Microgrids via Cyber-Physical Coordination
Mengxiang Liu, Xin Zhang, Shiyi Zhao et al. (+1 more)
In parallel to the cyber attack that manipulates the reference points of distributed energy resources (DERs) by maliciously accessing the remote monitoring and control system, the vulnerability of voltage/current sensors to electromagnetic interference (EMI) in the physical domain has been widely discussed. Existing research efforts against sensor spoofing attacks can be classified into physical prevention and cyber detection/mitigation. These defence methods each have strengths and weaknesses in balancing cost, security, and performance in a single DER, yet systematic research on their multi-layer efficient coordination across DERs remains limited. Towards this end, this paper proposes a hierarchical framework to detect and mitigate sensor spoofing attacks in networked microgrids (NMGs) via {multi-layer cyber-physical coordination}. It requires only to deploy physical prevention technologies at critical points, i.e., the local points of common coupling (PCC) of MGs, such that cyber detection/mitigation
algorithms can be adopted based on the secured sensor readings to counter sensor spoofing attacks in DERs. The framework employs an MG-DER coordinated proactive detection scheme to strategically trigger parameter perturbations, under which the intelligent sensor spoofing attacks can be {effectively} disclosed. Afterwards, mitigation schemes based on MG-DER coordination are activated to recursively and accurately estimate sensor biases. Experiments on a cyber-physical DC NMG testbed confirm the framework's effectiveness across diverse attack scenarios.
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All authors Mengxiang Liu, Xin Zhang, Shiyi Zhao, Ruilong Deng
Systems and Control
Control Barrier–Value Functions under Partial Observability: Safety Guarantees via Conformal Prediction
Niloofar Jahanshahi and Mo Chen
This paper studies safety analysis and controller synthesis for partially observable nonlinear control systems. We extend the control barrier–value function (CBVF) framework, which combines Hamilton–Jacobi reachability and control barrier functions, to settings where full state information is not available and control is based on an estimated state. Given an
estimator, we apply conformal prediction to the estimation error and obtain an error bound at a user-chosen miscoverage level. We incorporate this bound into the
estimator-space safety analysis and define a CBVF-based safety certificate for partially observable systems. We then derive a finite-horizon probabilistic safety guarantee for the true system state. Finally, we propose a QP-based online safety filter for systems affine in the control and disturbance, whose solution enforces the CBVF safety condition in real time against bounded disturbance. The proposed framework is illustrated on a partially observable obstacle-avoidance case study.
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Audio and Speech Processing
Trajectory Dynamics in Self-Supervised Learning Latent Space for Audio Deepfake Detection
Tomás Andrade Weber
Human
speech production is constrained by physiology, giving rise to characteristic temporal structure on acoustic signals. We hypothesise that these constraints manifest as structured trajectory dynamics in the latent space of Self-Supervised Learning (SSL) models, and that synthetic
speech violates them detectably. To test this hypothesis, we train a causal Long Short-Term
Memory (LSTM) next-frame predictor on bonafide
speech only (Stage 1), using the deepfake-specialised SSL backbone Wav2Vec2-Large-AntiDeepfake, and compare against a static global-average-pooling baseline using identical features, thus isolating the contribution of temporal modelling. A supervised Stage 2, which trains a Multi-Layer Perceptron on the frozen LSTM internal states using labelled data, is included to characterise the role of spoof supervision. Our system achieves competitive or state-of-the-art performance across six
benchmarks: ASVspoof 2019/2021, Codecfake, In-the-Wild, MLAAD-EN, and Deepfake-Eval-2024, including best published EER on ASVspoof 2021 (0.75%) and, notably, Stage 1 trained on bonafide
speech only surpasses the published supervised baseline from the same backbone on DE2024 (30.35%). On near-domain
benchmarks, static and dynamic approaches perform comparably. On harder cross-corpus
benchmarks with diverse synthesis methods, trajectory dynamics provide substantial gains, confirming that temporal physiological constraints carry detection signal beyond utterance-level statistics.
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Signal Processing
Compact Microstrip Triplexer Using Square Open-Loop Resonators with High Isolation for 5G Sub-6 GHz Applications
Bhaskarareddy N C, Rashmi Ravi and Augustine O. Nwajana
The rapid proliferation of multi-standard 5G New
Radio sub-6 GHz systems have intensified the demand for compact, high-isolation multiplexing components capable of simultaneously routing multiple frequency channels through a single shared
antenna port without cross-band interference. This paper presents the design and full-wave electromagnetic simulation of a compact microstrip triplexer operating at 2.2, 2.6, and 3.0 GHz for 5G sub-6 GHz applications. The proposed triplexer employs square open-loop resonators arranged as three independent three-pole Chebyshev bandpass filter channels, yielding nine resonator poles in total. Each channel is synthesised from the standard normalised Chebyshev lowpass prototype. The three channels are integrated at a common input port via a T-junction, with connecting transmission line stubs dimensioned to enforce high inter-channel isolation. Full-wave EM simulation results demonstrate return losses of 21.1 dB, 23.1 dB, and 22.8 dB; insertion losses of 1.08 dB, 1.01 dB, and 0.98 dB; and inter-channel isolations of 45.7 dB, 45.2 dB, and 45.7 dB, respectively. The achieved inter-channel isolation exceeding 45 dB represents a significant improvement over the majority of recently reported microstrip triplexer designs.
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Image and Video Processing
VLM- and LLM-Driven Multi-Agent System for PET Image Denoising
Boxiao Yu, Savas Ozdemir, Yang Xing et al. (+8 more)
Positron emission
tomography (PET) imaging suffers from limited spatial resolution and low signal-to-noise ratio, which can compromise quantitative accuracy and lesion detectability. Deep learning-based denoising methods have demonstrated strong potential for improving PET image quality. However, their practical deployment in real-world settings remains challenging, often requiring multiple specialized models and expert interventions, such as identifying motion-induced misregistration artifacts, estimating noise levels to select an appropriate denoiser, and performing lesion-focused quantitative assessment after denoising. Recent advances in
vision-
language models (VLMs) for image quality understanding and large
language models (LLMs) for contextual
reasoning provide new opportunities for automated, decision-driven workflows. Inspired by expert workflows for PET image quality enhancement, we propose an VLM- and LLM-driven multi-
agent PET denoising framework that dynamically assesses image quality and lesion status, autonomously selects optimal denoising models and parameters, and enables closed-loop feedback with rollback mechanisms. Experiments were conducted on Siemens Biograph
Vision Quadra PET/CT data with 1/20 and 1/50 low-dose settings. Individual module evaluations demonstrated the reliability of the agentic components, while the complete framework achieved higher PSNR and SSIM than UNet, GAN, and DDPM baselines at both dose levels. These preliminary results demonstrate the feasibility of using a closed-loop multi-
agent framework to adapt PET denoising strategies to different image conditions.
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All authors Boxiao Yu, Savas Ozdemir, Yang Xing, Fumio Hashimoto, Jiong Wu, Yizhou Chen, Axel Rominger, Ruogu Fang, Kuangyu Shi, Tinsu Pan, Kuang Gong
Signal Processing
Energy Efficient Multi-User Beamforming and 3D Position Optimization for SIM-Assisted UAVs
Chandan Kumar Sheemar, Giovanni Iacovelli, Sourabh Solanki et al. (+3 more)
This paper studies energy-efficient downlink multi-user transmissions with unmanned aerial vehicle (
UAV) communication systems equipped with stacked intelligent metasurfaces (SIM), enabling wave-domain analog beamforming through multiple cascaded metasurface layers, while low-dimensional digital precoding is carried out using a limited number of transmit
radio-frequency chains. This architecture enables flexible electromagnetic wave manipulation with reduced hardware complexity, making it particularly suitable for energy-constrained aerial platforms. We formulate a hardware-aware energy-efficiency (EE) maximization problem aiming to jointly optimize the digital precoder, the phase shifts of all SIM layers, and the three-dimensional
UAV position under transmit-power, SIM operation, and
UAV deployment constraints. The resulting problem is highly non-convex due to the fractional objective, the cascaded SIM structure and the unit-modulus phase constraints of the constituent metasurface layers, as well as the non-linear
UAV-dependent channel. To address these challenges, we develop a transform-based alternating optimization framework that combines Dinkelbach's method, dual and quadratic transforms, to enable closed-form digital beamforming, Riemannian
manifold optimization for SIM phase shifts, and successive convex approximation (SCA) for
UAV positioning. Convergence and complexity analyses are provided to characterize the proposed
algorithm. The presented numerical results showcase that the proposed joint design significantly improves EE compared with fully digital and maximum ratio transmission
benchmark schemes, while revealing important design trade-offs among transmit power, SIM size, and the number of its constituent stacked layers.
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All authors Chandan Kumar Sheemar, Giovanni Iacovelli, Sourabh Solanki, Wali Ullah Khan, George C. Alexandropoulos, Symeon Chatzinotas
Audio and Speech Processing · Cross-listed from cs.CL
StreamHear: Domain-Adapted Pseudo-Labeling for Semi-Supervised Streaming Speech Recognition
Zefang Liu, Chenyang Zhu, Sangwoo Cho et al. (+3 more)
Streaming automatic
speech recognition (ASR) underperforms on domain-shifted target audio, where labeled in-domain data is costly to prepare while unlabeled audio is abundant. We present StreamHear, a semi-supervised pipeline that adapts a pretrained streaming student by fine-tuning an offline transducer teacher on the labeled training set, generating pseudo-labels on the unlabeled portion, and fine-tuning the student on the mixture. We further introduce a prior-regularized dynamic-programming realignment step that fixes chunk-level word placement using an ASR-hypothesis anchor. Across four
datasets spanning financial calls, prepared read
speech, and phone-quality dialogue, StreamHear consistently outperforms supervised student fine-tuning and narrows the gap to the offline teacher.
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All authors Zefang Liu, Chenyang Zhu, Sangwoo Cho, Xujun Peng, Shi-Xiong Zhang, Sambit Sahu
Image and Video Processing
TRUE-Colon: Exposing a Consistent Transfer Asymmetry in Real-Time Polyp Detection
Sebastian Doerrich, Andreas Franz Schwab, Francesco Di Salvo et al. (+3 more)
Computer-aided detection (CADe) systems for colonoscopy promise to reduce clinical miss rates, yet reliable real-world deployment remains elusive. This translational gap stems in part from a structural flaw in model development: the reliance on curated
datasets that under-represent the long negative stretches and procedure-related artifacts characteristic of routine examinations. Training and evaluating architectures strictly on these lesion-centric
benchmarks creates an illusion of success, since such
benchmarks cannot capture clinically crucial metrics. To expose this gap, we establish TRUE-Colon, a standardized benchmarking protocol that measures key deployment characteristics alongside localization accuracy, and evaluate four real-time architectures (Faster R-CNN, YOLOv8, YOLOv11, RT-DETR) across curated
benchmarks (SUN, PICCOLO) and 60 unedited, full-length procedures (REAL-Colon). We observe a consistent transfer asymmetry: models trained strictly on curated clips suffer a severe performance collapse when evaluated on full procedures, whereas procedure-trained models substantially improve rejection of non-polyp content on REAL-Colon, and largely retain their accuracy on curated
benchmarks. Beyond transferability, we find that the
Transformer detector attains the strongest sensitivity and the earliest, most persistent detections, while the convolutional detectors stay competitive at a higher throughput. Together, these results indicate that both training and benchmarking for deployable CADe should shift from curated, lesion-centric clips toward full-procedure data and deployment-relevant operating points. Source code is available at https://github.com/sdoerrich97/true-colon.
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All authors Sebastian Doerrich, Andreas Franz Schwab, Francesco Di Salvo, Shyam Nandan Rai, Hanh Huyen My Nguyen, Christian Ledig
Systems and Control
Consistent Model Chasing Is Minimax Optimal: The Exact Value of Scalar Adversarial Adaptive Control under Large Parametric Uncertainty
Dimitar Ho
We solve exactly a fundamental problem of adaptive control against
adversarial disturbances: regulate the scalar system $x_{t+1} = ax_t + u_t + w_t$, $x_0=0$, $\|w\|_\infty \le 1$, where the constant pole $a \in [-\Delta, \Delta]$ is unknown in sign and magnitude and $\Delta$ is arbitrarily large. Elementary as the system looks, the least worst-case peak $\|x\|_\infty$ that a causal controller can guarantee against an
adversarial pair $(a, w)$ (the value of this game) has, to our knowledge, never been determined for any adaptive control problem with parametric uncertainty of arbitrary size under this criterion; existing theory supplies stability certificates, gain bounds, and regret rates, not the value. That value is $\gamma^\star(\Delta) = 1 + \Delta$ for every $\Delta>0$. The summand $1$ is the irreducible price of the disturbance, and $\Delta$ the exact price of a single, unavoidable identification spike. The optimal policy is certainty-equivalent deadbeat control at the midpoint of the set-membership consistent interval, an instance of the robust oracle $\times$ consistent model chasing architecture. The architecture is forced, not merely sufficient: writing $\theta_t := -u_t/x_t$ exhibits every causal controller as an oracle-selector composition, and optimality pins the selector to the midpoint at the critical histories. The standard tools, classical and modern, each fail quantifiably: probing is punished before it pays, commitment is fatal at sub-disturbance excitation once adaptation is necessary, optimism degenerates to tie-breaking or pays asymptotically at least twice the optimum, and regret certificates are blind to the worst-case peak in both directions. The optimal law contains no exploration mechanism, its learning purely passive. These results give the first exact optimality certificate for consistent model chasing as a design principle for
adversarial adaptive control.
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Systems and Control
Joint Communication-Control Strategy Optimization with Partially Nested Information Structures: The Linear-Quadratic Case
Haoyi You and Kaiqing Zhang
In this paper, we formalize a joint communication-control strategy optimization (JCCO) problem in multi-
agent linear systems with quadratic costs, under the common-information-based (CIB) framework from decentralized
stochastic control. For computational tractability, we focus on such JCCO problems with partially nested (PN) information structures (ISs). In particular, with a baseline communication protocol that leads to a PN IS, we establish a series of conditions under which the partial nestedness is preserved under the (additional) communication strategies to be optimized, while violating them may cause nonlinearity of the optimal strategies in general, with open-loop communication strategies. We then develop a dynamic-programming-based approach to compute the optimal control strategies of JCCO with open-loop communication strategies, which yields a set of closed-form Riccati Equations. As a byproduct of independent interest, such an approach also offers a way to solve decentralized linear-quadratic control with PN ISs and output feedback, under the CIB framework. Finally, we extend such an approach to JCCOs with closed-loop communication strategies, yielding a more tractable dynamic program than an infinite-dimensional CIB-belief-based one.
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Systems and Control
Safety-Critical Control for Quadrotor UAVs via Decentralized Navigation Functions
Omayra Yago Nieto, Alexandre Anahory Simoes and Leonardo Colombo
We study safety-critical control for teams of quadrotor
UAVs driven by decentralized navigation functions under learned model uncertainty. These functions generate fully actuated translational reference forces, while quadrotors can only produce thrust along their body-fixed vertical axes. We construct a thrust-attitude implementation of the induced navigation forces and quantify its error with respect to the fully actuated reference dynamics. An aggregated robust HOCBF-QP safety filter minimally modifies the nominal thrusts while guaranteeing pairwise collision avoidance with high probability.
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Signal Processing · Cross-listed from physics.optics
In-situ Adjoint Wave Control in Reconfigurable Non-Hermitian Nonlinear Systems
John Guillamon, William Tuxbury, Cheng-Zhen Wang et al. (+3 more)
Complex multipath environments are usually avoided in wave-based information processing because repeated scattering creates many interfering propagation paths, obscuring controllability and generating extreme sensitivity to perturbations. The addition of nonlinear mechanisms fundamentally alters the wave-control landscape by breaking the superposition principle that underpins most wave-management strategies. Here, we show that these two apparent impediments – multipath complexity and nonlinearity – can instead be harnessed as key resources for physical optimization. We demonstrate an in-situ adjoint optimization protocol in a wave-chaotic platform incorporating a single localized nonlinear defect, in which the system itself performs both the forward and the adjoint propagations required for gradient evaluation. Recurrent multipath returns repeatedly expose the wave to the defect, producing from a minimal hardware a rich nonlinear input-output map with many pathway-mediated degrees of freedom. At the same time, a suitable adjoint excitation enables direct extraction of the sensitivities from measurements alone, without a digital twin or conventional numerical backpropagation. We experimentally validate the protocol on a minimal nonlinear multipath platform composed of incommensurate coaxial cables connected via T-junctions, one of which hosts a diode-loaded cavity. Our approach opens a route to adaptive wireless communications, imaging and analog intelligence in complex, partially unknown environments where conventional modeling is impractical.
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All authors John Guillamon, William Tuxbury, Cheng-Zhen Wang, Owen Miller, Zin Lin, Tsampikos Kottos
Systems and Control
AaLLM: An End-to-End Analog Circuit Design Framework from Topology Generation to Sizing Using Large Language Models
Mohammed Ayman Habib, Rylan Hart and Morteza Fayazi
Analog
circuit design is a time-consuming, iterative process in a nonlinear and high-dimensional design space that relies heavily on expert intuition. Among recent developments, LLMs have introduced a promising approach by bringing natural
language reasoning to
circuit design tasks. The majority of conventional LLM-based approaches provide fragmented solutions that focus either only on sizing or
topology generation. These methods require adding specific technical knowledge manually, which is inefficient and prone to
hallucinations during
circuit sizing. Moreover, the inherent trade-off in meeting different specs makes current approaches iterative and tedious. Another shortcoming is the inability to create innovative
topologies, which may lead to sub-optimal designs due to reliance on conventional
topologies. In this paper, we present AaLLM, an open-source end-to-end multi-
agent LLM workflow that takes user specs as input and outputs the appropriate netlist, encompassing both
topology generation and
circuit sizing. AaLLM automates the creation of a relevant knowledge base from research papers and textbooks to combat tedious manual data collection. A RAG model is implemented to emulate
circuit design expertise using this knowledge base. Moreover, AaLLM uses a novel tri-
agent feedback system comprising a Designer that determines
circuit component values, a Critic that scrutinizes these values, and an Evaluator that minimizes
circuit sizing iterations by arbitrating between the other two
agents. AaLLM-generated novel
topologies achieve a figure of merit (FoM) comparable to that of known
topologies, and up to 3x higher for certain
circuits. Testing on several
circuit topologies, our results show a 3x - 4.5x decrease in the number of SPICE calls at inference when compared to SOTA multi-
agent LLM pipelines. The results also show a 40x decrease in wall-clock time compared to existing approaches.
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Signal Processing
On-Off Digital Noise Modulation with Fluid Antenna Systems over $\kappa$-$\mu$ Fading Channels
Daniel C. Araújo, André A. dos Anjos, Hugerles S. Silva et al. (+2 more)
This letter proposes the integration of on-off digital noise (OODN) modulation with fluid
antenna systems (FASs). A unified analytical framework is developed to evaluate the performance of FAS- assisted OODN receivers over additive white Gaussian noise and generalized ąppa}-{\mu} fading channels. The analysis incorporates fluid
antenna port selection, the number of available ports, and spatial correlation. Analytical expressions for the average bit error probability are derived and the achievable diversity order is characterized. All expressions are validated through Monte Carlo simulations. Results demonstrate that the spatial diversity provided by the FAS significantly enhances the reliability of OODN transmissions while preserving their inherent low-complexity, non-coherent operation without carrier-phase recovery. The proposed framework establishes a new research direction for energy-efficient Internet of Things (IoT) and machine-type communication systems.
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All authors Daniel C. Araújo, André A. dos Anjos, Hugerles S. Silva, Constantinos Psomas, Robson D. Vieira
Signal Processing
Low-Complexity Channel Parameter Estimation for Coprime HRIS-Assisted MIMO Systems
Jean C. S. Ferreira, Melryllin G. O. Sousa and Fazal-E Asim
This paper proposes a parameter estimation scheme for uplink
MIMO systems assisted by a Hybrid Reconfigurable Intelligent Surface (HRIS). To reduce hardware complexity, the HRIS employs a small number of active elements arranged in a sparse coprime geometry for local sensing, while the remaining elements passively reflect signals. This simultaneous sensing and reflection significantly improves accuracy over fully passive architectures. The method leverages Khatri-Rao and Kronecker factorizations to efficiently decouple the cascaded channel at the base station. Furthermore, spatial smoothing resolves the coprime array rank deficiency, enabling robust angular extraction via Root-MUSIC. Simulations demonstrate highly resilient estimation performance across scenarios.
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Audio and Speech Processing · Cross-listed from cs.CL
Motor, Cognitive, or Corpus? What Survives Cross-Lingual Transfer in Speech-Based Parkinsons Disease Detection
Serli Kopar, Sam Gijsen, Abner Hernandez et al. (+2 more)
Self-supervised learning (SSL)
speech representations achieve strong performance for Parkinson's disease (PD) detection within individual corpora. However, it remains unclear whether these models capture disease-related characteristics or exploit
dataset-specific confounds, particularly since most SSL backbones are pretrained exclusively on healthy
speech. To investigate this question, we perform a layer-wise analysis of nine SSL
speech backbones using a low-capacity logistic regression probe across three
languages. We structure the evaluation as multiple scenarios that progressively introduce distribution shifts in participant identity, recording conditions,
language, and pathology. Our results reveal two key findings. First, layer selection is highly corpus-dependent: the optimal representation layer is determined primarily by the source
dataset rather than by the SSL architecture itself. Second, the transferred discriminative signal lacks pathological specificity: classifiers trained to detect PD assign similarly high probabilities to both PD and dementia
speech in the target corpus. These results highlight critical limitations that must be addressed before
speech-based pathology recognition models can be reliably deployed in clinical settings.
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All authors Serli Kopar, Sam Gijsen, Abner Hernandez, Paula Andrea Perez-Toro, Kerstin Ritter
Signal Processing
Heterogeneity-Aware Belief Synchronization for Semantic Communication in AI-Native 6G Networks
Muhammad Hannan Akram, Muhammad Abubakar Rashid, Wassi Haider Kabir et al. (+3 more)
6G networks will not be serving as communication infrastructures only; rather, they are expected to evolve into intelligent systems, where thousands of autonomous artificial intelligence (AI)
agents are interconnected. The
agents are deployed across a wide range of platforms including low Earth orbit (LEO) satellites, high-altitude platforms (HAPs), unmanned aerial vehicles (
UAVs), edge servers, and terrestrial devices. These
agents continuously observe their environment and exchange information. Semantic communication provides an efficient mechanism for exchanging meaningful information instead of raw data. However, its effectiveness depends on the communicating
agents having sufficiently aligned beliefs to correctly interpret and decode the transmitted messages. This assumption becomes difficult to satisfy in the 6G network where heterogeneous AI models operate under diverse computational constraints and continuously acquire different knowledge from their local environments. This article presents a heterogeneity-aware belief synchronization framework for 6G AI-native networks. It uses latent translation models deployed on multi-access edge computing (MEC) servers. These models translate belief updates from one
agent to
agent-specific knowledge without requiring joint training and a homogeneous architecture of models. By exchanging compact belief updates through a latent translation model only when necessary, the framework preserves
privacy, reduces synchronization cost, and minimizes local knowledge drift. We validate the framework through a case study on a multi-layered terrestrial/non-terrestrial network. Results demonstrate that it maintains low synchronization cost, measured by the number of parameters transmitted, and low belief
alignment error across the heterogeneous
agents in the case study.
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All authors Muhammad Hannan Akram, Muhammad Abubakar Rashid, Wassi Haider Kabir, Haejoon Jung, Kapal Dev, Syed Ali Hassan
Systems and Control
Process-Aware Cross-Layer Adaptation for O-RAN-Enabled Industrial Systems
Elahe Delavari, Junaid Farooq, M. Majid Butt et al. (+1 more)
Wireless networks increasingly support closed-loop industrial applications in which sensed data must be transmitted, processed, and converted into an action before physical process makes the result obsolete. Throughput, latency, and inference accuracy measured separately cannot determine whether such an application completed a useful task. We propose a Process-Aware Co-adaptation Engine framework that combines application outcomes, process state,
radio telemetry, edge-compute state, and sensing configuration to select coordinated operating points across the complete loop. We evaluate the proposed approach in a factory-inspection case study that integrates a physics-based digital twin, a programmable 5G O-RAN network, and edge-based visual inference. The experiments show that the preferred resource allocation changes with production speed and that adapting individual system components independently can be inefficient. We further show that efficient configurations can be identified with relatively few full-system evaluations.
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All authors Elahe Delavari, Junaid Farooq, M. Majid Butt, Quanyan Zhu
Systems and Control
Robust Space-Filling Input Design via Stochastic Optimization
Máté Kiss, Roland Tóth and Maarten Schoukens
The space-filling input design approach generates a so-called space-filling
dataset in the feature space of the system model. The design method is applicable on a broad class of model structures with wide selection of signals and also incorporates information measures through optimality criteria into the signal design. However, during the signal design, knowledge of a hypothesized model is required. The designed signal can perform far from the optimal if the true system is significantly different from the hypothesized system model. This paper proposes a robust space-filling input design
algorithm that can generate a space-filling
dataset for an entire class of models. The proposed
algorithm takes the expectation of an optimality criterion over the population of the model class, and a
stochastic approximation technique is employed to optimize this robust criteria. The efficiency of the proposed
algorithm is demonstrated in a simulation example.
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Signal Processing
A Physically Consistent Assessment of Nearfield Beamfocusing into Occluded Regions
Georg Schwan, Alexander Stutz-Tirri and Christoph Studer
Recent work has explored elaborate beamfocusing techniques for the radiative nearfield, with some studies suggesting that certain beamshapes, such as Airy beams, can enable efficient electromagnetic (EM) wave transmission behind obstacles. In this letter, we ask whether the added complexity of such techniques is justified. We distinguish between partially and fully occluded regions. In the partially occluded region, where Airy beams are commonly employed, we show that a simple line-of-sight (LoS) strategy, which activates only
antennas having an unobstructed view of the receiver, is near-optimal and outperforms Airy beams at substantially lower complexity. In the fully occluded region, we argue that accurate beamfocusing requires a physically consistent EM wave propagation model that captures propagation effects such as diffraction. Once such a model is available, however, the optimal beamfocusing strategy has a closed-form solution and can be computed directly. These results suggest that elaborate techniques, such as Airy beams, offer little benefit over simpler alternatives for beamfocusing into occluded regions.
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Signal Processing
Foundation models for movement data: Are they ready for prime-time?
Alexander Bräuer, Benjamin Cauchi and Nils Strodthoff
Foundation models (FMs) trained on large-scale accelerometer data have been proposed as general-purpose feature extractors for health monitoring, but systematic evidence of their advantages is lacking. We present the first comprehensive evaluation of four open-source accelerometer FMs against supervised baselines covering 19 tasks across the domains of activity recognition including activities of daily living, clinical monitoring, and physiological inference. We find task-dependent performance results: supervised models remain competitive with FMs on human action recognition (HAR), with no consistent advantage for either, while selected FMs lead on fall and stress detection and are the most robust to sensor-placement variation. As frozen feature extractors, FMs are strongest for demographic inference, whereas sleep staging performance remains near chance level for all models. The internal FM representations show strong similarity across layers, highlighting potential for future FM improvements. Linear and frozen probing reveals that UniMTS provides the strongest representations and is the only FM that surpasses the supervised baselines without finetuning. Concept discovery analysis shows all models capture high-intensity activities clearly but struggle with sedentary, complex or ambiguous activities. We provide scenario-based deployment recommendations. Furthermore, we identify FM-derived activity profile inference-moving beyond fixed category classification-as a promising research direction.
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