Signal Processing · Cross-listed from cs.IT
Gaussian Belief Propagation for Tracking With Unresolved Measurements
Augustin A. Saucan, Florian Meyer and Peter Willett
Unresolved measurements occur in many inference problems where two or more hidden processes may, at times, jointly generate a single measurement. For instance, such phenomena are encountered in multiobject tracking owing to the limited resolution capabilities of practical sensors; or in camera-aided autonomous driving due to shadowing or occlusions. Substantial performance degradation, such as track losses, are incurred when unresolved measurements are not accounted for. In this paper, we address multiobject tracking under a generalized unresolved measurement model, where any subset of objects may generate a single unresolved measurement according to a probabilistic model. Our innovation lies both in modeling and
algorithm-design directions. First, we develop a probability distribution for object partitions based on a model of pairwise coupling of objects and subsequently a probability distribution for object-to-measurement association variables. This generic model incorporates sensor resolution capabilities, sensor detection, and sensor noise characteristics for object groups. Second, a generic Loopy Belief Propagation (LBP) method as well as a specialized Gaussian-LBP (GLBP)
algorithm are proposed that perform object state inference under the aforementioned model. In contrast to direct marginalization methods, which involve a computational complexity of $O(m^n)$, for $m$ measurements and $n$ objects, the proposed GLBP
algorithm achieves a computational complexity on the order of $O(m n 2^{n})$. Numerical results demonstrate the effectiveness of our proposed GLBP, with estimation performance that closely matches that of exact marginalization for only a fraction of the computational resources.
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Signal Processing
Resource-Efficient Wi-Fi CSI-Based Sensing via Exploiting the Age of Samples
Abolfazl Zakeri, Nhan Thanh Nguyen and Markku Juntti
Wi-Fi channel state information (CSI)-based sensing must coexist with data communications, limiting the availability of temporally-dense CSI measurements. We formulate CSI-based human activity and identity recognition under an average sensing budget that limits the fraction of CSI measurement and reporting opportunities within a sensing session. The budget captures sensing-communication resource sharing, packet loss, and traffic-induced irregularity, which we model using deterministic (accumulated) and
stochastic (Bernoulli) sampling policies. We propose a low-cost, age-aware WiFi sensing framework that encodes the age of each retained CSI sample and multiplicatively fuses it with the CSI
embedding. On the NTU-Fi human activity recognition and person identification
datasets, the proposed model outperforms both a CSI-only baseline and the time-aware
attention model of the UniFi
benchmark across most operating regimes. For person identification, it improves over UniFi by more than 10 percentage points, with the largest gains under strict sensing budgets.
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Systems and Control
A Tutorial on Autonomous Fault-Tolerant Control Using Knowledge-Grounded LLM Agents
Javal Vyas, Milapji Singh Gill, Artan Markaj et al. (+2 more)
Fault recovery in process plants still relies heavily on plant operators, especially when faults fall outside predefined supervisory logic. Operators interpret alarms, procedures, P&IDs, interlocks, and process trends, then decide how to move the plant to a safe operating mode without triggering a shutdown. This paper examines how Large
Language Model (LLM)
agents can support such recovery decisions. The proposed framework treats the LLM as a constrained supervisory planner. It uses plant-specific knowledge to propose recovery actions, and every proposal is checked by an external validator (symbolic or simulation-based) before actuation. The paper develops three design dimensions for applying the framework: the recovery patterns for which LLM
agents are useful, the validation strategies that separate admissible from inadmissible proposals, and the deployment constraints imposed by latency, knowledge engineering, safety integration, and model lifecycle management. To make the framework directly usable, two openly available executable Python environments are provided. Both re-implement established case studies, a modular mixing module and a continuous stirred-tank reactor, extended with configurable faults and defined interfaces for custom recovery and validation methods.
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All authors Javal Vyas, Milapji Singh Gill, Artan Markaj, Felix Gehlhoff, Mehmet Mercangöz
Systems and Control
Automating Cause-Effect Specification with Knowledge Graphs and Large Language Models
Javal Vyas, Milapji Singh Gill and Mehmet Mercangöz
Engineering specifications such as interlocks, alarm rationalization tables, and cause-and-effect (C&E)
matrices remain central to process control and safety, yet their creation is still predominantly manual, document-driven, and prone to inconsistency. This paper presents a semantic-AI framework that automates the generation of C&E logic by combining a knowledge graph (KG) with a constrained large
language model (LLM) layer. The KG builds on an established modular
alignment ontology to represent process structure, operating modes, faults, symptoms, causes, and mitigation actions in a machine-interpretable form. The LLM then transforms this information into operator-ready safety narratives and Semantic Web Rule
Language (SWRL) rules under strict ontology and vocabulary constraints, grounding the generated artifacts in the underlying semantic model. The workflow is demonstrated on a modular process plant, showing how engineering semantics, diagnostic relations, and machine-verifiable specifications can be generated from a unified knowledge representation with reduced manual effort.
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Systems and Control
Uncertainty Quantification via Invariant-Measure Conformal Prediction
Mohammadhossein Bakhtiaridoust, Dominik Baumann and Shankar Deka
Uncertainty quantification for learned
stochastic dynamical systems is essential in safety-critical tasks such as control and monitoring. Standard conformal prediction provides finite-sample coverage guarantees under exchangeability, but this assumption is typically violated in dynamical systems because trajectory data are temporally dependent, state distributions evolve, and recursive prediction errors accumulate. This paper proposes an invariant-measure conformal prediction (imCP) framework that calibrates uncertainty using independent samples from an invariant measure of the Markov process induced by the dynamics. This aligns calibration with the stationary operating regime and restores the statistical
symmetry needed for rolling one-step split conformal guarantees. For recursive multi-step prediction, imCP combines conformal calibration with Lipschitz error propagation through the learned predictor to obtain explicit horizon-dependent bounds.These pre-deployment uncertainty tubes are suitable for rolling and receding-horizon applications, such as self-triggered control and fault detection, where uncertainty bounds must be computed before future residuals are observed. Numerical experiments show that imCP yields reliable bounds, while non-invariant calibration can become misaligned during deployment.
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Audio and Speech Processing · Cross-listed from cs.SD
Dilemmadata: On the Interoperability of Heterogeneous Roman Numeral Datasets
Johannes Hentschel, Emmanouil Karystinaios, Gerhard Widmer et al. (+1 more)
In recent years, there has been growing effort to annotate and collect large-scale corpora of Roman numeral analyses in support of data-driven studies in tonal harmony. We introduce dilemmadata, the first resource to reconcile two major collections, the AugmentedNet
Dataset (AN) and the Distant Listening Corpus (DLC), making them interoperable through a shared note-wise TSV schema. The reconciliation confronts four families of dilemmata: annotation-standard (the two encode the same musical fact differently in terms of vocabulary size, syntax, conventions for chord extensions, inventory of special chord functions), representational (what counts as a row, and which information survives the conversion), toolchain (incompatible Python ecosystems built around music21 vs. ms3+dimcat), and curatorial (which pieces to include, exclude, or retain twice). We resolve each by deliberately transforming, augmenting, and omitting information, formalising the mismatches, preserving musical semantics, and flagging transformations that may subtly affect annotation fidelity. Consistency checks and qualitative inspections offer a preliminary assessment of post-conversion validity and a basis for critiquing the theoretical assumptions embedded in each original standard. After removing duplicates and merging the two collections, the resulting dilemmadata (1,621 pieces and aprox. 2.8 M note-wise annotations) is the largest homogeneous Roman-numeral corpus currently available, albeit far from perfect. Crucially, we retain 84 pieces common to both corpora under each of their original analyses, yielding a shared reference set in which two equally legitimate analytical traditions can be compared note-for-note over identical musical material. Released on Zenodo, dilemmadata supports interoperability, comparative harmonization modeling, and future refinement of Roman-numeral encoding standards.
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All authors Johannes Hentschel, Emmanouil Karystinaios, Gerhard Widmer, Markus Neuwirth
Systems and Control
Fast Risk Certification of Candidate Trajectories under Uncertain Time-Varying Constraints
Srimanta Santra, Oleksii Molodchyk, Matti Noack et al. (+1 more)
This paper studies the certification of a fixed candidate trajectory on a finite certification grid under parametric uncertainty. For each constraint-time pair, we define a scalar measure of constraint violation and aggregate the resulting pointwise chance constraints into a worst-case Value-at-Risk (VaR) margin. The goal is not to generate a new trajectory, but to assess online whether a trajectory produced by a planner or predictive controller is sufficiently safe on the certification grid. Direct evaluation requires repeated uncertainty propagation and is often too expensive for computationally demanding models. We therefore adopt an offline-online scheme: offline, a surrogate of the constraint violation map along the candidate trajectory is constructed using
polynomial chaos expansion (PCE) when the uncertainty law is known, or kernel regression when only sampled input-output data are available; online, the surrogate is sampled to evaluate conservative VaR bounds at low computational cost. On the theoretical side, we derive a finite-sample upper bound for the grid-based VaR margin using empirical
quantiles, the Dvoretzky-Kiefer-Wolfowitz (DKW) inequality, and a union bound over all constraint-time pairs, without assuming a parametric family for the underlying violation distribution. We also show how a uniform surrogate error bound transfers to the certified VaR margin. The approach is illustrated on a crystallization population balance model, where the surrogate-based risk estimates track direct Monte Carlo results while substantially reducing online evaluation time.
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All authors Srimanta Santra, Oleksii Molodchyk, Matti Noack, Timm Faulwasser
Audio and Speech Processing
Improving multichannel speech enhancement through accurate room-acoustic simulations
Georg Götz, Alessia Milo, Steinar Gu{\dh}jónsson et al. (+3 more)
Room-acoustic simulations are widely used to augment training data for deep-learning-based
speech enhancement. While most pipelines rely on simplified geometrical acoustics, wave-based approaches offer greater physical accuracy. In this work, we examine how simulation fidelity affects multichannel
speech enhancement performance. To this end, we train SpatialNet on
datasets augmented with different room-acoustic simulation methods and evaluate the resulting models on measured data. We compare lower-fidelity
datasets based on geometrical acoustics with a high-fidelity
dataset using advanced acoustic modelling and a hybrid combination of wave-based and geometrical acoustics simulations. Training on the high-fidelity
dataset results in an up to 38 % relative reduction in median word error rate compared to the lower-fidelity alternatives. These results show that augmentation with high-fidelity room-acoustic simulations directly translates into improved multichannel
speech enhancement performance.
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All authors Georg Götz, Alessia Milo, Steinar Gu{\dh}jónsson, Daniel Gert Nielsen, Jesper Pedersen, Finnur Pind
Audio and Speech Processing
How Bilingual Are SSL Speech Models? Cross-Lingual Probing of Articulatory Encoding with Finnish and Russian EMA
Ailín Pollio San Pedro, Tomi Kinnunen, Alexandre Nikolaev et al. (+1 more)
SSL
speech models capture rich phonetic, prosodic, and acoustic patterns from raw audio, yet how they encode articulatory information across diverse
languages remains unclear. Using EMA data from bilingual Finnish-Russian speakers, we evaluate cross-lingual correlations between SSL latent representations and articulatory movements. Models achieve strong prediction performance (Pearson r up to 0.68) even with approximately 5 minutes of training data, with
multilingual models outperforming monolingual ones. Intermediate layers encode articulatory features most effectively, and tongue movements are more predictable than lip movements. We also assess the impact of task type (read versus spontaneous
speech) and
language proficiency, finding higher accuracy for structured tasks and strong generalization across proficiency levels. These results enhance the interpretability of SSL models and show their potential for
speech-technology applications.
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All authors Ailín Pollio San Pedro, Tomi Kinnunen, Alexandre Nikolaev, Ruchi Pandey
Image and Video Processing
Distortion-Corrected Diffusion MRI Using Rotated-View EPI and Joint Field-Map/Image Estimation with Gaussian Primitives
Wenqi Huang, Zhitao Li, Nan Wang et al. (+8 more)
Echo Planar Imaging (EPI) is the standard acquisition technique for
diffusion and functional neuroimaging, enabling rapid imaging but suffering from
geometric distortions caused by B0 field inhomogeneities. Existing correction methods first reconstruct distorted images using parallel imaging, then estimate the B0 field and correct the distortion in the image domain. In this sequential process, reconstruction artifacts at high acceleration factors and low SNR at high
diffusion b-values degrade B0 estimation and limit the overall correction quality. We propose a physics-informed framework that jointly estimates the B0 field and distortion-free image directly from k-space data, without depending on an intermediate parallel-imaging reconstruction for the correction. The image and the B0 field are each represented as a superposition of Gaussian primitives embedded within an MRI physics forward model. The explicit, continuous parameterization captures both smooth regions and tissue boundaries and supports rotated-view EPI acquisitions without interpolation. The
diffusion-weighted image is modeled as real and non-negative, with the image phase absorbed into a per-shot phase factor. Rotated views distribute distortions across multiple phase-encoding orientations, improving point spread function isotropy and providing stronger constraints for B0 estimation. On in vivo
brain diffusion EPI, the proposed method attains the closest
brain-boundary agreement with a distortion-free structural reference, with the largest improvement over sequential methods at high b-value and high acceleration. Extensive visual comparisons further show improved detail fidelity and noise suppression.
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All authors Wenqi Huang, Zhitao Li, Nan Wang, Yimeng Lin, Mengze Gao, Yurui Qian, Sevgi Gokce Kafali, Xiaozhi Cao, Kawin Setsompop, Daniel Rueckert, Congyu Liao
Signal Processing
Von Mises Based Uncertainty Quantification for Closely Spaced Automotive Radar Targets
Vinay Kulkarni and V. V. Reddy
This work investigates uncertainty-aware deep learning approaches for direction of arrival (DOA) estimation in automotive radar, focusing on probabilistic modeling and downstream integration. A circular-statistics-based von Mises (VM) ensemble (ENS) is compared with an evidential deep learning (EDL) framework based on a normal inverse gamma formulation, yielding a Student t predictive distribution in the Euclidean domain. The ENS framework produces angular predictions parameterized by (mu, kappa), enabling interpretable uncertainty aligned with directional geometry. Performance is evaluated under in distribution and multiple out-of-distribution conditions using risk coverage and ROC or AUROC analyses. Results indicate that ENS achieves lower uncertainty under nominal conditions and exhibits stronger sensitivity to severe perturbations, whereas EDL provides smoother uncertainty variation and slightly improved ranking consistency. Importantly, the ENS representation enables direct probabilistic integration into association modules via closed form VM likelihoods, facilitating a unified detection tracking pipeline. These findings highlight a trade-off between
geometric consistency and statistical generality in uncertainty-aware DOA estimation.
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Signal Processing
Sensing for Reliable UAV Communication: Robust Trajectory and Resource Optimization in Low-Altitude Networks
Yifan Jiang, Qingqing Wu, Hongxun Hui et al. (+3 more)
In low-altitude wireless networks, sensing-aided communication has emerged as a promising integrated sensing and communication (
ISAC) paradigm for unmanned aerial vehicle (
UAV) tracking and communication. This paper investigates reliable sensing-aided communication for multiple cellular-connected
UAVs under mobility uncertainties. Specifically, we maximize the minimum outage capacity among
UAVs by jointly optimizing their real-time predicted positions, as well as the base station (BS) transmit power and bandwidth allocations. To address the non-convex and intractable maximum tolerable outage probability (OP) constraints, two robust optimization schemes are proposed based on a continuous confidence ellipse (CE) and discretized inverse-whitened sectors (IWSs), respectively. For the CE-based scheme, an efficient
algorithm is proposed to optimize the predicted
UAV positions individually via block successive convex approximation, followed by convex resource allocation. For the IWS-based scheme, an IWS-based OP approximation is proposed to facilitate the robust optimization, based on which a low-complexity IWS selection method is proposed to decouple the optimization variables. Then, a similar sequential optimization
algorithm is proposed based on the projected gradient descent approach. The two
algorithms are further unified into a common trajectory-resource optimization framework, revealing a low-complexity structure for robust
UAV trajectory and resource management. Simulation results validate the effectiveness of our proposed OP approximation, demonstrate the significant outage capacity improvement of the proposed robust optimization schemes over
benchmark schemes, and illustrate the superiority of the IWS-based scheme over the CE-based scheme.
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All authors Yifan Jiang, Qingqing Wu, Hongxun Hui, Wen Chen, Wei Feng, Shanpu Shen
Signal Processing
Towards a Joint Task-Oriented and Generative Semantic Communication Framework for 6G Networks
Soheyb Ribouh and Phil Polo Ditsia Di Ngoma
Semantic Communication (SC) has emerged as a key enabler for 6G wireless systems by transmitting task-relevant meaning rather than raw data, thereby significantly reducing bandwidth consumption while preserving communication intent. In this work, we propose an end-to-end OFDM-based semantic communication framework that integrates a semantic encoder-decoder pipeline with a neural receiver operating over a 3GPP vehicular channel. The semantic encoder extracts the underlying meaning of a visual scene by transforming it into a graph-based representation consisting of object-level features and relational structure. At the receiver, the reconstructed scene graph is processed by a spatio-temporal graph neural network (ST-GNN)-based module for collision-risk estimation, enabling task-oriented inference. In parallel, a
diffusion-based semantic decoder reconstructs the visual scene from the recovered semantics, providing dual functionality: safety prediction and image reconstruction. The proposed framework is evaluated in a
MIMO configuration under varying SNR conditions. Experimental results show that it achieves up to 99.1% data compression relative to pixel-domain transmission, outperforming conventional compression-based methods (JPEG and HEVC) while preserving downstream inference performance. Furthermore, the
diffusion-based reconstruction attains significantly lower frechet inception distance (FID) scores than existing semantic communication approaches, reflecting superior semantic and perceptual fidelity.
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Systems and Control · Cross-listed from cs.OS
Ensuring Deterministic Timing in a Federated GNSS Correction Pipeline with Lingua Franca
Tejeswini Jayaramareddy, Hokeun Kim and Hoeseok Yang
Embedded systems that combine hardware interrupts, buffering, and distributed communication are often perceived as inherently asynchronous and difficult to analyze. However, such systems can exhibit a deterministic timing structure when modeled using explicit logical-time semantics. This paper presents a Global
Navigation Satellite System (GNSS) correction-data pipeline implemented as a
federated Lingua Franca (LF) application. The
federated LF program decomposes the end-to-end pipeline into reactors with explicit time semantics, including a time-triggered GNSS receiver, a UART interrupt stream derived from baud rate and First-In First-Out (FIFO) buffer characteristics, a periodic forwarding task, and downstream processing with jitter monitoring.
Federated execution and runtime logs validate the analytically derived deterministic timing structure-including interrupt cadence, ring-buffer
evolution, packetization behavior, and physical–logical jitter-yielding a reproducible and predictable timing profile.
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Signal Processing
Rethinking Energy Efficiency in Cell-Free Massive MIMO: The Role of Processing and Optical Fronthaul
Ozan Alp Topal, Özlem Tuğfe Demir and Cicek Cavdar
Cell-free massive
MIMO promises uniformly high performance by combining densely distributed
radio units, coherent transmission, and centralized processing. Unlike earlier
radio generations, it depends on dense fronthaul connectivity and a virtualized cloud-RAN architecture. In this setting, energy use is no longer driven primarily by active
radio components; instead, fronthaul and processing play a dominant role, calling for a fresh perspective on what defines energy efficiency. This work introduces a modular power model that captures the interplay between
radios, fronthaul, and cloud processing. The analysis highlights how design choices, such as functional splits and precoding strategies, shape both fronthaul data load and total power consumption. Centralized precoding provides stronger performance with less resource utilization, while flexible activation of
radios and processing elements avoids unnecessary overhead. Overall, the energy efficiency of
cell-free massive
MIMO grows as
antennas are more densely distributed across the coverage area, particularly when combined with end-to-end resource allocation.
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Signal Processing
Transformer-Hypernetwork-Controlled Deep-Unfolded Phase-Aware Channel Estimation Refinement for Phase-Drift-Robust Backscatter Links
Hanyeol Ryu, Nohgyeom Ha and Sangkil Kim
This paper proposes a
transformer-hypernetwork-controlled deep-unfolded phase-aware channel estimation refinement (THUNDER) for phase-drifting backscatter links. Residual carrier-phase drift across the pilot block renders the backscattered observation phase-nonstationary, and a closed-form phase-aware channel estimation (PACE) compensates only the first-order phase component, leaving a deterministic high signal-to-noise ratio (SNR) error floor. THUNDER suppresses this floor by initializing from PACE and refining the estimate through unfolded Gauss-Newton steps on the exact phase-exponential model. A
transformer extracts pilot-wide phase context, and a hypernetwork generates bounded controls and pilot-reliability weights. Evaluations show an 8.9 dB normalized mean square error gain over the strongest learning-based channel estimation baseline.
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Systems and Control
How Much Sensing Information Is Needed to Control an Unstable Linear System?
Ming Li, Fan Liu, Yifeng Xiong et al. (+4 more)
Modern control systems increasingly rely on sensing to infer the system state before control actions can be taken. Yet a given observation mechanism may fail to preserve sufficient information about the unstable modes, regardless of the downstream
estimator or controller. This paper asks how much sensing information is needed to estimate and control an unstable linear system, whose measurements are generated by a prescribed, possibly nonlinear and non-Gaussian, observation law p(y_t|x_t). To address this question, we first quantify sensing information using directed information, thereby accounting for causal feedback. We then establish necessary and sufficient information rate conditions for estimating and controlling this linear system. For necessity, keeping either the estimation error or the closed-loop state bounded in mean square requires a directed information rate of at least the open-loop expansion rate R_exp. This lower bound remains valid under additive process noise. Since this rate is difficult to evaluate, we derive computable bounds for nonlinear observations with additive noise. An upper bound below R_exp certifies infeasibility, whereas a lower bound above R_exp + R_NG certifies sufficiency under posterior covariance regularity. For linear Gaussian observations, the tight upper bound is determined by the steady-state Riccati equation. For sufficiency, the posterior non-Gaussianity rate R_NG measures the divergence rate from the covariance-matched Gaussian. Under uniform posterior covariance regularity, a rate above R_exp + R_NG guarantees mean-square convergence of the estimation error. For a stabilizable plant, certainty-equivalence feedback also guarantees mean-square convergence of the closed-loop state. Finally, verifiable
curvature conditions on the likelihood and prior make R_NG vanish, so the sufficient threshold equals R_exp.
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All authors Ming Li, Fan Liu, Yifeng Xiong, Jie Xu, Tao Liu, Weijie Yuan, Shi Jin
Systems and Control
Continuous-Time Decentralized Online Estimation With Additive Noises
Xiaozheng Fu, Yan Chen and Tao Li
We study a decentralized online estimation problem with additive communication noises over the fixed digraph. Each node has a linear measurement of an unknown parameter with random measurement
matrices and runs a continuous-time online estimation
algorithm. We transform the convergence analysis of the
algorithm into the stability analysis of the non-autonomous linear
stochastic differential equation (SDE) with random time-varying coefficients, and develop the asymptotic stability by numerical approximation theory. Based on the stability results, we show that the
algorithm gains can be properly designed to ensure mean square convergence if the measurement
matrices and the communication graph satisfy the
stochastic spatial-temporal persistence of excitation condition. Furthermore, a special case where the measurement
matrices contain a Markov chain is investigated, and the theoretical results are demonstrated by a numerical example.
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Audio and Speech Processing
Beyond Cross-Reconstruction: Probing-Based Disentanglement Evaluation for Acoustic Teleportation Codecs
Philipp Grundhuber and Emanuël A. P. Habets
Some neural audio codecs disentangle
speech into latent subspaces encoding content, speaker identity, and acoustics, enabling acoustic teleportation and voice conversion. Existing evaluations rely on cross-reconstruction quality, which cannot reliably detect leakage across partitions. We extend a probing based framework to assess disentanglement by regressing room-acoustic parameters (reverberation time, clarity, and direct-to-reverberant ratio) and classifying speaker identity, using the gap between intended and unintended partitions as the disentanglement measure. Applied to an acoustic teleportation codec, we find speaker identity is largely confined to its partition, while acoustics leak into the
speech embeddings due to the training objective. Acoustic
embeddings blindly estimate room parameters within 0.02 s of supervised baselines, indicating physically meaningful structure emerges without explicit supervision.
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Signal Processing · Cross-listed from cs.LG
Dualformer: Efficient Feature Extractor for Complex-valued Blind Communication Signal Analysis
Yurui Zhao, Xiang Wang, Jingreng Lei et al. (+3 more)
Designing effective feature extractors is critical for blind signal analysis tasks such as automatic modulation recognition (AMR), signal scheme recognition (SSR), and \color{black} signal structure parsing (SSP). In this work, we propose dual-channel neural network (DualNN) that efficiently exploits complex-valued signals through parameter sharing across IQ channels. Unlike traditional real-valued or complex-valued models, DualNN is a groundbreaking framework which shares the network parameters for processing the real and imaginary parts of the complex-valued signals, and is theoretically shown to reduce generalization error while preserving expressive capacity. Specifically, we propose a novel
Transformer-based architecture to implement DualNN, called Dualformer. The Dualformer segments input signals into patch-level
tokens and captures multi-granularity features, enabling robust performance across diverse signal analysis tasks. Furthermore, we conduct extensive experiments comparing Dualformer with three
Transformer-based baselines and four conventional DL-based approaches. Results demonstrate consistent performance improvements on AMR, SSR, and SSP tasks. Besides, the modular design of DualNN allows it to generalize well to blind signal processing tasks such as blind source separation and low-SNR spectrum sensing. This work paves the way for a broader application of DualNN architectures in unsupervised and weakly supervised complex-valued signal analysis scenarios.
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All authors Yurui Zhao, Xiang Wang, Jingreng Lei, Wanlong Zhang, Yik-Chung Wu, Zhitao Huang
Signal Processing
PGUDA: Pressure-Guided Unsupervised Domain Adaptation with Cross-Modal Knowledge Distillation for sEMG-Based Gesture Recognition
Yurui Liu, Xiao-Cong Zhong, Qisong Wang et al. (+3 more)
Surface electromyography (sEMG)-based gesture recognition has emerged as a promising technology for natural human-computer interaction. However, its practical deployment remains challenging due to severe performance degradation caused by feature distribution discrepancies across different subjects and recording sessions. Although domain adaptation (DA) techniques are commonly employed to mitigate such discrepancies, conventional methods often struggle to effectively aligning sEMG features, primarily due to their inherent stochasticity and the scarcity of labeled data. To address these limitations, this paper proposes a novel Pressure-Guided Unsupervised Domain Adaptation (PGUDA) framework, which leverages the robustness and stability of pressure signals to introduce a cross-modal knowledge
distillation strategy that transfers consistent physical semantics across modalities. Specifically, a teacher network trained on pressure signals guides an sEMG student network on unlabeled target domains, thereby regularizing the representation learning process with transferable and modality-invariant knowledge. Extensive experiments conducted on a self-collected
multimodal dataset involving eleven subjects validate the effectiveness of the proposed PGUDA framework. The results demonstrate that our proposed PGUDA achieves leading performance in both cross-subject and cross-session classification tasks, achieving average accuracies of 58.08% and substantially outperforming existing DA approaches. Notably, PGUDA exhibits remarkable label efficiency: it attains classification accuracy comparable to fully supervised
benchmarks while requiring only 5% of labeled data for teacher network training. This framework offers a robust and data-efficient solution that can significantly reduce the calibration burden in practical sEMG-based gesture recognition systems.
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All authors Yurui Liu, Xiao-Cong Zhong, Qisong Wang, Xuefu Wang, Dan Liu, Jinwei Sun
Systems and Control
Standardizing case study descriptions for multi-energy systems and networks modeling
Mathieu Vallee, Eva Schischke, Edmund Widl et al. (+11 more)
Research on Multi-Energy Systems (MES) often relies on case studies with divergent hypotheses and terminologies, limiting comparability and slowing progress. Discussions at the ECOS 2025 conference highlighted the need for standardized reference case studies to facilitate reuse and comparison. While frameworks like the IEC 62559 standard and the Open Energy Platform (OEP) exist, their adoption for MES remains fragmented. This heterogeneity hinders collaboration and replicability, motivating efforts towards a unified description framework tailored to MES. This paper aims to address this gap by evaluating existing approaches in order to promote a standardized description framework for MES case studies. The goal is to enhance comparability, streamline research, and make a first step towards defining reference case studies and
benchmarks in the domain. The study adopts a collaborative approach: after analysing existing description frameworks and selecting the most suitable one, the co-authors describe their own case studies, followed by cross-reviews to assess completeness, clarity, and openness of data/models. The description framework is adapted to emphasizeMES-specific elements, such as system configuration and use case details. A checklist is developed to guide reviews. Preliminary results include a set of standardized case study descriptions and insights from cross-reviews on framework strengths/limitations. The diversity of case studies underscores the framework's flexibility, while feedback reveals opportunities for improvement and broader adoption. This work provides a foundation for standardized MES case study descriptions, fostering collaboration, comparability, and replicability. By reducing ambiguity and ensuring the availability of relevant information in a consistent format, it accelerates research and benchmarking in the field.
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All authors Mathieu Vallee, Eva Schischke, Edmund Widl, Gabriela Zabik, Mohamed-Tahar Mabrouk, Kai Derzsi, Dirk Müller, Sergio Rech, Costanza Saletti, Martina Capone, Sacha Hodencq, Ildar Daminov, Gabriele Leoncini, Marc Clausse
Audio and Speech Processing · Cross-listed from cs.SD
Beyond Binary Instrument QA: Probing Instrument Grounding in Music Audio-Language Models
Yujun Lee, Joonhyeok Shin, Hyoeun Kim et al. (+1 more)
Recent music audio-
language models achieve high accuracy on instrument question-answering
benchmarks, but it remains unclear whether this reflects robust audio grounding or
benchmark-specific shortcuts. In this paper, we introduce an OpenMIC-derived diagnostic
benchmark sequence for instrument grounding in music audio-
language models, extending binary instrument-presence QA to genre-prior-reduced examples, confusable instrument discrimination, longer audio context, and temporal localization. Across these settings, high binary QA accuracy often fails to predict model behavior: models can exhibit option-position bias, confusable-instrument errors, and temporal response bias. These results suggest that instrument grounding should be evaluated with multi-axis diagnostic
benchmarks rather than a single aggregate accuracy.
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All authors Yujun Lee, Joonhyeok Shin, Hyoeun Kim, Kyuhong Shim
Signal Processing · Cross-listed from physics.optics
Fundamentals of Optical Fiber Sensing Schemes Based on Coherent Optical Time Domain Reflectometry: Signal Under Dynamic Temperature Conditions
Roman Ermakov, Huwei Wang, Florian Azendorf et al. (+4 more)
We present a theoretical, algorithmic, and experimental study of temperature sensing using $\phi$-OTDR with coherent detection. A physics-based model is developed to relate the measured Rayleigh backscattered signal to temperature variations along the fiber, showing that the phase
evolution encodes the cumulative temperature change between the interrogator and the sensing location, while the amplitude exhibits only local sensitivity. Based on this insight, we propose robust
algorithms for temperature-event detection and temperature-profile reconstruction. Experimental results demonstrate reliable recovery of temperature-induced perturbations in standard single-mode fibers using coherently detected $\phi$-OTDR.
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All authors Roman Ermakov, Huwei Wang, Florian Azendorf, André Sandmann, Juan M. Marin, Francesco Da Ros, Darko Zibar
Systems and Control · Cross-listed from quant-ph
Projection Operator Stochastic Equations for Non-Markovian Quantum Systems Under Continuous Measurement-Based Feedback
H. I. Nurdin
Quantum Markov models have been successfully used to accurately model various physical
quantum systems in fields such as
quantum optics, optomechanics and superconducting
circuits and they provide the basis for (measurement-based)
quantum feedback control. However, the
quantum Markov assumption is a strong one and it is not expected to hold for general
quantum systems of interest. The projection operator approach is one approach that has been developed to model non-Markovian
quantum systems by considering its
embedding in a larger Markovian
quantum system, but mainly in the context of
quantum master equations for the dynamics of the unmonitored reduced
quantum state of a
quantum system. This approach was recently adapted for continuously measured non-Markovian
quantum systems, which enables open-loop control but did not yet consider the presence of feedback of the
stochastic measurement record, deriving non-Markovian SDEs for the
evolution of the projected state of the Markovian
embedding. This paper generalizes these
stochastic equations to the setting of
stochastic feedback based on the continuous-measurement record and shows that the equations take the same form but that previously deterministic terms become
stochastic ones which depend on the measurement record, as would be intuitively expected. The
stochastic equations are obtained for a generalized class of measurements that includes continuous (possibly adaptive) homodyne and
photon counting measurements.
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Systems and Control
A Novel Method for Differential-Algebraic Dynamic Model Discovery in Power Systems: An LLM-Based Multi-Agent Collaborative Framework
Xinming Wang, Fan Tang, Yingli Wei et al. (+6 more)
With large-scale integration of emerging power electronic devices represented by grid-forming inverters, power system dynamics increasingly exhibit strong nonlinearity, multi-timescale coupling, and black-box control logic. These features hinder conventional parameter identification requiring known model structures and structure identification based on predefined function libraries, making complete differential-algebraic dynamic model recovery difficult under weak prior information. To address this challenge, this paper proposes an LLM-based multi-
agent collaborative framework for differential-algebraic dynamic model discovery in power systems. It integrates heterogeneous exploratory
agents, individual candidate model
memories, parameter fitting and evaluation, and a coordinator
agent. Under unified measurement-data constraints,
agents generate candidate equation structures in parallel, while candidates are optimized, evaluated, retained, and summarized to provide closed-loop search guidance. The task is decomposed into differential equation structure discovery and algebraic closure discovery, enabling joint recovery of state dynamics, algebraic constraints, and key intermediate variables with incomplete prior information. Case studies on synchronous generators and grid-forming inverters show that the proposed method outperforms single-
agent LLM-based discovery and conventional symbolic regression in reconstruction accuracy, generalization, search efficiency, and noise robustness. In the generator case, OOD MAPE reaches 0.19%; in the inverter case, discovery time is reduced by 25.7% compared with the single-
agent LLM baseline.
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All authors Xinming Wang, Fan Tang, Yingli Wei, Yakun He, Zhe Liu, Ping Jiang, Haoyu Wu, Zihan Guo, Chao Shen
Signal Processing
Minimizing Quantized Semantic Age of Information (QSAoI) in Foundation Model-Based Semantic Communications
Huanyu Zhang, Yulin Hu, Xiaopeng Yuan et al. (+2 more)
The emerging techniques of semantic communications and edge computing in 6G networks necessitate a paradigm shift toward co-designed semantic-aware and adaptive resource allocation for short-packet transmissions. However, there is a fundamental gap between the semantic layer and the physical layer under low-latency finite blocklength (FBL) effects. To bridge this gap, we introduce the Quantized Semantic Age of Information (QSAoI), a novel metric that rigorously captures the trade-offs among freshness and semantic efficiency of high-level features in real-time communication in the FBL regime. Guided by this metric, we propose a novel foundation model-based efficient co-designed framework to minimize the expected QSAoI over wireless fading channels in latency-constrained semantic communication. Specifically, we formulate a non-linear joint optimization problem to dynamically optimize the block-wise mixed-precision quantization (MPQ) strategy and the physical blocklength. To efficiently resolve this complex problem, we develop a high-efficiency low-complexity
algorithm based on fixpoint inspection and bisection search. Extensive simulations validate that our proposed
algorithm dynamically adapts the semantic quantization precision to varying channel conditions, effectively minimizing the expected QSAoI compared to baselines.
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All authors Huanyu Zhang, Yulin Hu, Xiaopeng Yuan, Aydin Sezgin, Anke Schmeink
Signal Processing · Cross-listed from cs.IT
Fundamental Limits of Quantized MIMO ISAC under Gaussian Signaling
Hossein Atrsaei, Mireille Sarkiss and Michèle Wigger
We study a quantized multiple-input multiple-output (
MIMO) integrated sensing and communication (
ISAC) system in which the communication and sensing receivers each apply analog spatial combining followed by scalar subtractive dithered quantization. This quantization model leads to an additive effective-noise representation with non-Gaussian noise. We derive upper and lower bounds on the capacity of this channel. Numerical results show that these bounds are tight at low signal-to-noise ratios (SNR) and saturate at high SNR due to finite-resolution quantization. They also show that, despite the effective noise being non-Gaussian, independent and identically distributed (i.i.d.) isotropic Gaussian signaling achieves rates close to capacity. Focusing on i.i.d. Gaussian signaling, this paper also presents a closed-form expression for the linear minimum mean-squared error (LMMSE) achieved under a Kronecker sensing-channel model. Numerical results show that the LMMSE also saturates at high SNR, where the saturation level increases as the spatial combining ratio decreases, and for combining ratios below one, saturation occurs even without quantization.
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Audio and Speech Processing · Cross-listed from cs.SD
SwiftAudio: Data-Efficient Caption-Only Distillation for One-Step Text-to-Audio Diffusion-based Generation
Binh Mai, Tran Quoc Bao Le, Hung Dinh et al. (+1 more)
Diffusion-based text-to-audio (TTA) models achieve impressive synthesis quality but suffer from high inference latency due to iterative multi-step denoising. Existing one-step approaches alleviate this issue but still rely on paired text–audio data during
distillation. To address these limitations, we propose SwiftAudio, a one-step TTA framework that performs audio-free
distillation from a pretrained
diffusion teacher using only text captions. Specifically, we adapt Variational Score
Distillation (VSD) to the audio domain and introduce a temporal smoothness regularization objective to encourage coherent latent audio representations. This design enables the student model to inherit the teacher's generative prior without requiring paired audio supervision and allows effective training with only approximately 45K captions. Experiments on AudioCaps and Clotho demonstrate that SwiftAudio achieves state-of-the-art performance among strict one-step methods and substantially narrows the gap to multi-step
diffusion systems. Project page: https://swiftaudio.org/
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All authors Binh Mai, Tran Quoc Bao Le, Hung Dinh, Cong Tran
Audio and Speech Processing · Cross-listed from cs.SD
FlexiSLM: A Spoken Language Model with Dynamic and Controllable Frame Rates
Jiaqi Li, Chaoren Wang, Xiaohai Tian et al. (+9 more)
Spoken
language models (SLMs) extend LLMs to
speech input and output, but existing systems use fixed frame rates (e.g., 25 or 12.5 Hz), overlooking
speech's time-varying information density and limiting inference-time quality-speed tradeoffs. Recent dynamic-frame-rate audio tokenizers enable very low average frame rates and controllability, yet had not been applied to SLMs. We introduce FlexiSLM, the first SLM with dynamic, controllable frame rates, using pretrained FlexiCodec for dynamic
speech output
tokens. It integrates this representation into a multi-task
speech-to-
speech SLM, extends it with input-side frame compression, and adds direct frame-rate conditioning for accurate control during inference. FlexiSLM outperforms fixed-frame-rate 7B models, including Qwen2.5-Omni and Kimi-Audio, at 12.5 and 6.25 Hz; it can be steered down to 4.0 Hz, and at 6.25 Hz roughly halves inference time relative to 12.5 Hz while retaining strong
speech-to-
speech quality. Audio samples: https://flexislm.github.io; code and data: https://github.com/AmphionTeam/FlexiSLM.
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All authors Jiaqi Li, Chaoren Wang, Xiaohai Tian, Mingjie Chen, Xinyu Liang, Xu Li, Yufan Lin, Junwen Qiu, Jun Zhang, Lu Lu, Haizhou Li, Zhizheng Wu