Image and Video Processing
Set-Based Groupwise Registration for Variable-Length, Variable-Contrast Cardiac MRI
Yi Zhang, Yidong Zhao, Tijmen Toxopeus et al. (+3 more)
Quantitative cardiac
magnetic resonance imaging (MRI) enables non-invasive myocardial tissue characterization but relies on robust motion correction within these variable-length, variable-contrast image sequences. Groupwise registration, which simultaneously aligns all images, has shown greater robustness than pairwise registration for motion correction. However, current deep-learning-based groupwise registration methods cannot generalize across MRI sequences: the architecture typically encodes input data as a fixed-length channel stack, which rigidly couples network design to protocol-specific sequence length, input ordering, and contrast dynamics. At inference time, any change in imaging protocols will render the network unusable. In this work, we introduce \AnyTwoReg, a new set-based groupwise registration framework that takes a quantitative MRI sequence as an unordered set. This set formulation fundamentally decouples network design from sequence length and input ordering. By utilizing a shared encoder and correlation-guided feature aggregation, \AnyTwoReg constructs a permutation-invariant canonical reference for registration, and learns a permutation-equivariant mapping from images to deformation fields. Additionally, we extract contrast-insensitive image features from an existing foundation model to handle extreme contrast variations. Trained exclusively on a single public $T_1$ mapping
dataset (STONE, sequence length $L=11$), \AnyTwoReg generalizes to two unseen quantitative MRI
datasets (MOLLI, ASL) with variable lengths ($L \in [11, 60]$) and different contrast dynamics. It achieves strong cross-protocol generalization in a zero-shot manner, and consistently improves downstream quantitative mapping quality. Notably, while designed for quantitative MRI sequences, our framework is directly applicable to Cine MRI sequences for inter-cardiac-phase registration.
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All authors Yi Zhang, Yidong Zhao, Tijmen Toxopeus, Maša Božić-Iven, Sebastian Weingärtner, Qian Tao
Signal Processing
Exponential Noise Robustness of Type-Based Multiple Access for Over-the-Air Computation
Marc Martinez-Gost, Ana Pérez-Neira and Miguel Ángel Lagunas
This paper studies the robustness of type-based multiple access (TBMA) in over-the-air computation (AirComp) under nonparametric estimation, where no prior knowledge of the data distribution is available. While conventional AirComp approaches rely on amplitude modulations and suffer from noise sensitivity, TBMA enables the use of more structured modulation formats that can be exploited for improved performance. We show that the superposition of transmitted signals in TBMA induces a discrete
lattice structure in the received signal space, where each
lattice point corresponds to the number of devices accessing a given channel resource. By exploiting this structure through nearest-
lattice-point projection, noise effects can be substantially suppressed. The proposed technique achieves an exponential decay of the mean squared error (MSE) with respect to the energy-to-noise spectral density ratio, whereas in conventional techniques the MSE only scales inversely with this ratio. Simulation results validate the theoretical findings and demonstrate that TBMA provides a fundamental robustness advantage over traditional AirComp.
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Systems and Control · Cross-listed from cs.MA
Effect of Graph Gluing on Consensus in Networked Multi-Agent Systems
Rohollah Moghadam and Santosh Kandel
In this paper, the effects of graph gluing operations in networks of multi-
agent systems and their impact on system performance are investigated. In many practical applications, multiple multi-
agent subsystems must be interconnected through communication links to accomplish complex tasks, resulting in a larger communication network. Such interconnections modify the underlying graph
topology and consequently affect the consensus behavior and convergence rate of the network. In particular, this paper examines both bridge gluing and interface gluing and analyzes how the number and structure of communication links between subsystems influence the Fiedler
eigenvalue of the resulting graph. Since the Fiedler
eigenvalue is directly related to the convergence rate of consensus dynamics, the proposed analysis establishes a clear relationship between interconnection strategies, algebraic connectivity, and system performance. The results provide theoretical insight into how different gluing mechanisms alter the spectral properties of the graph
Laplacian and, in turn, the convergence characteristics of the networked multi-
agent system. Simulation studies are presented to illustrate the theoretical findings and to validate the effectiveness of the proposed framework.
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Systems and Control
Equivariant Observer Design on SL(3) for Image Intensity-Based Homography Estimation
Tarek Bouazza, Pieter van Goor, Robert Mahony et al. (+1 more)
This paper addresses the problem of homography estimation using a nonlinear observer designed on the Lie group $\mathbf{SL}(3)$ that exploits the full image information through direct image registration. Unlike traditional feature-based methods, which rely on extensive feature extraction and matching, the proposed approach formulates an observer that minimises a cost function defined directly in terms of image pixel intensities. Explicit conditions ensuring the non-degeneracy of the cost function are derived, and a comprehensive analysis is conducted to characterise and generate degenerate (unobservable) image configurations. Theoretical results demonstrate local exponential convergence of the observer. To improve local convergence properties, a second-order observer variant is introduced by incorporating the Hessian of the cost function into the correction term. Simulation results demonstrate the performance of the proposed solutions on real images.
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All authors Tarek Bouazza, Pieter van Goor, Robert Mahony, Tarek Hamel
Systems and Control · Cross-listed from math.OC
A PAC-Bayes Approach for Controlling Unknown Linear Discrete-time Systems
Yujia Luo, Ye Pu, Jonathan H. Manton et al. (+1 more)
This paper presents a PAC-Bayes framework for learning controllers for unknown
stochastic linear discrete-time systems, where the system parameters are drawn from a fixed but unknown distribution. We derive a data-dependent high probability bound on the performance of any learned (
stochastic) controller, and propose novel efficient learning
algorithms with theoretical guarantees, which can be implemented for both finite and infinite controller spaces. Compared to prior work, our bound holds for unbounded quadratic cost. In the special case where LQG is optimal, our numerical results suggest that the learned controllers achieve comparable performance to LQG.
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All authors Yujia Luo, Ye Pu, Jonathan H. Manton, Jingge Zhu
Systems and Control
Glycemic Safety Tube: A Provably Safe Control Framework for Artificial Pancreas Systems under Parametric Uncertainty
Pukhrambam Akash Singh, Ratnangshu Das, Ahan Basu et al. (+1 more)
Type 1 diabetes eliminates the body's ability to produce insulin, making glucose regulation entirely dependent on external insulin delivery and the control
algorithm. Existing closed-loop methods either rely on accurate patient-specific models or do not provide formal safety guarantees, and are often computationally demanding for wearable devices. This paper proposes Glycemic Safety Tube Control (GSTC), a model-free and computationally efficient control framework for automated insulin delivery. The method enforces clinically relevant safety bounds on glucose levels by design, ensuring that glucose remains within a prescribed safe range. We also derive feasibility conditions that guarantee safety and input constraint satisfaction under bounded meal disturbances and estimation errors. The performance of GSTC is evaluated against state-of-the-art methods, including linear and nonlinear model predictive control and sliding mode control. The results demonstrate that GSTC maintains safety under varying meal patterns and patient conditions, highlighting its robustness and computational efficiency. Overall, GSTC provides a safe, efficient, and patient-independent approach for next-generation artificial pancreas systems.
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All authors Pukhrambam Akash Singh, Ratnangshu Das, Ahan Basu, Pushpak Jagtap
Systems and Control
Observing the state of networks with directed higher-order interactions
Roberto Rizzello, Davide Salzano, Stefano Boccaletti et al. (+1 more)
We consider the problem of reconstructing the state of a network of nonlinear dynamical systems in the presence of directed higher-order interactions. Grounded on analytical convergence results, we propose an algorithmic observer design procedure that simultaneously selects the nodes to be measured and the observer gains. We complement the theoretical analysis with an exhaustive numerical investigation campaign that showcases the performance and robustness of the designed observer. Finally, the algorithmic procedure is used to fully reconstruct the opinions of a group of
agents.
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All authors Roberto Rizzello, Davide Salzano, Stefano Boccaletti, Pietro De Lellis
Systems and Control
Priority-Driven Control and Communication in Decentralized Multi-Agent Systems via Reinforcement Learning
Qingyun Guo, Junyi Shi, Tomasz Piotr Kucner et al. (+1 more)
Event-triggered control provides a mechanism for avoiding excessive use of constrained communication bandwidth in networked multi-
agent systems. However, most existing methods rely on accurate system models, which may be unavailable in practice. In this work, we propose a model-free, priority-driven reinforcement learning
algorithm that learns communication priorities and control policies jointly from data in decentralized multi-
agent systems. By learning communication priorities, we circumvent the hybrid action space typical in event-triggered control with binary communication decisions. We evaluate our
algorithm on
benchmark tasks and demonstrate that it outperforms the baseline method.
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All authors Qingyun Guo, Junyi Shi, Tomasz Piotr Kucner, Dominik Baumann
Signal Processing · Cross-listed from cs.IT
Syndrome Adaptive Gain Control for Min-Sum Decoding of Quantum LDPC Codes
Hernan Cordova, Alexios Balatsoukas-Stimming, Yunus Can Gültekin et al. (+2 more)
Min-Sum (MS) decoding is a popular low-complexity alternative to belief propagation (BP), retaining only the minimum incoming message magnitude during check-node (CN) processing, at the cost of systematic message magnitude overestimation. The scaled MS (SMS) decoder compensates for this effect using a fixed scaling factor. We propose the syndrome adaptive gain Min-Sum (SAGMS) decoder for
quantum low-density parity-check (QLDPC) codes, which adapts the message gain online based on the fraction of unsatisfied stabilizers, requiring no per-code or per-noise level optimization. We show that the scaling factor required for SMS to match belief propagation decreases with the CN degree, so any fixed scaling optimized for one degree incurs into a growing penalty as the CN degree varies. SAGMS avoids this limitation by adapting the gain during decoding. Simulations on generalized bicycle QLDPC codes demonstrate that SAGMS matches or outperforms the frame error rate (FER) of an offline optimized SMS decoder. Moreover, SAGMS approaches BP performance and, under certain conditions outperforms it while retaining MS-level complexity.
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All authors Hernan Cordova, Alexios Balatsoukas-Stimming, Yunus Can Gültekin, Gabriele Liga, Alex Alvarado
Systems and Control
Hierarchical 2-degree-of-freedom control combining Youla-Kucera parameterization and model predictive control
Zhiheng Zhao, Hans Henrik Niemann and John Bagterp Jørgensen
A hierarchical 2DOF (2-degree-of-freedom) structure combining Youla-Kucera (YK) parameterization and model predictive control (MPC) is presented in this paper. The YK parameterization employs the coprime factorization of the nominal system and controller, thereby introducing an auxiliary feedforward channel dedicated to system optimization and a controller parameterization channel. The feedforward channel is utilized to implement cascaded MPC for system optimization. The controller parameterization channel is utilized to achieve offset-free MPC by designing an appropriate YK parameter through the H2 optimal controller design.
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Systems and Control · Cross-listed from astro-ph.IM
High-speed single-photoelectron detection for Cherenkov astronomy
Luca Giangrande, Matthieu Heller and Teresa Montaruli
Silicon photomultipliers are increasingly replacing photomultiplier tubes in Cherenkov
telescope cameras, but achieving single-photoelectron resolution with nanosecond timing in a low-noise, scalable detector system remains challenging. We present a co-designed SiPM sensor and front-end application specific integrated
circuit (ASIC) that meets these requirements. The custom hexagonal sensor, developed with Hamamatsu Photonics, incorporates an integrated optical filter and fourfold pixel
segmentation. The readout is performed by a second prototype of the FANSIC ASIC, optimized for this application and fabricated in 65~nm standard CMOS technology, it provides eight channels with on-chip analog summing of sub-channels on a $3.5\times 3.5~\mathrm{mm}^2$ die, while consuming only 24~mW per channel. We demonstrate clear single-photoelectron peak separation with a gain of $2.7 \times 10^{-12}~ \mathrm{V \cdot s}$ , and an impulse response below 4~ns full width at half maximum with a 1.7 ns rise time, preserving the nanosecond-scale structure of Cherenkov pulses. The system responds linearly from 1 to 130 photoelectrons, and 55 distinct photoelectron peaks are resolved by varying the source intensity. These results demonstrate that the integrated sensor-electronics architecture delivers the speed, resolution, and dynamic range required for imaging atmospheric Cherenkov
telescopes, and provides a scalable path toward large-area camera modules.
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Audio and Speech Processing
SF-Flow: Sound field magnitude estimation via flow matching guided by sparse measurements
Ege Erdem, Shoichi Koyama, Tomohiko Nakamura et al. (+2 more)
Reconstructing a 3D sound field from sparse microphone measurements is a fundamental yet ill-posed problem, which we address through Acoustic Transfer Function (ATF) magnitude estimation. ATF magnitude encapsulates key perceptual and acoustic properties of a physical space with applications in room characterization and correction. Although recent generative paradigms such as Flow Matching (FM) have achieved state-of-the-art performance in
speech and music generation, their potential in spatial audio remains underexplored. We propose a novel framework for 3D ATF magnitude reconstruction as a guided generation task, with a 3D U-Net conditioned by a permutation-invariant set encoder. This architecture enables reconstruction from an arbitrary number of sparse inputs while leveraging the stable and efficient training properties of FM. Experimental results demonstrate that SF-Flow achieves accurate reconstruction up to \SI{1}{kHz}, trains substantially faster than the autoencoder baseline, and improves significantly with
dataset size.
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All authors Ege Erdem, Shoichi Koyama, Tomohiko Nakamura, Orchisama Das, Zoran Cvetković
Signal Processing
Quantifying System Level KPI Deviations of Sionna RT: Material and Near-Field Error Analysis Using a 5G OAI Testbed
Faizan Rauf, Srijita Sanyal, Markus Heinrichs et al. (+1 more)
Ray tracing (RT) has recently gained renewed interest in wireless communications, driven by its integration into digital twin (DT) frameworks for site specific channel modeling. Several previous studies have validated RT at the channel level, yet how these errors propagate into real 5G system level key performance indicators (KPIs) on actual hardware remains unquantified. This paper addresses this gap by comparing Sionna RT simulated channels against vector network analyzer (VNA) measured channels using an OpenAirInterface (OAI) 5G NR testbed. Channel measurements are conducted at 20 receiver positions in an indoor laboratory, with both channel types injected into a hardware in the loop channel emulator interfacing an OAIBOX MAX base station and a Quectel UE. RSRP, PUCCH SNR, and SINR are evaluated under both conditions. The results identify
antenna near-field transition effects as a critical position-dependent error source, alongside material property mismatch, providing a quantitative
benchmark for digital twin-based 5G and beyond network planning.
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All authors Faizan Rauf, Srijita Sanyal, Markus Heinrichs, Aydin Sezgin
Signal Processing · Cross-listed from cs.LG
Foundations of Reliable Inference: Reliability-Efficiency Co-Design
Jiayi Huang
Reliable inference requires that artificial intelligence (AI) models provide trustworthy uncertainty estimates, not merely accurate predictions. Recent advances in
Bayesian learning have made significant progress toward this goal, and growing concerns about computational overhead have jointly shifted the design criterion from reliability alone to the co-design of reliability and efficiency, i.e., reducing computational overhead while preserving trustworthy uncertainty quantification. This thesis develops a unified framework from two perspectives to address the central question: can we efficiently perform reliable inference?
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Signal Processing
Signal-Dependent Shot Noise Modeling of Rydberg Atomic Quantum Receivers: A Design Perspective
Qihao Peng, Qu Luo, Tierui Gong et al. (+8 more)
In this paper, we develop a communication-oriented complex baseband equivalent model for superheterodyne Rydberg atomic
quantum receivers (RAQRs). The model explicitly captures photodetection-induced signal-dependent shot noise and its coupling with the optical operating point. By leveraging an atomic superheterodyne architecture and a strong local oscillator, we construct a complex baseband representation for both the received signal and the signal-dependent shot noise under both direct incoherent optical detection and balanced coherent optical detection. The derived model reveals that the optical operating point jointly determines the normalized effective receive gain and the equivalent noise background, thereby establishing a traceable gain-noise tradeoff governed by system design. More importantly, the proposed model shows that neglecting signal-dependent shot noise may lead to inaccurate operating-point design. Finally, by extending to the multiple-input-multiple-output (
MIMO) case, we derive a lower bound on the achievable rate while considering the signal-dependent shot noise. Our analysis \textcolor{black}{reveals} that the non-zero asymptotic rate of RAQ-
MIMO and its superiority over conventional RF-
MIMO hinge on the normalized noise floor of the RAQ receive chain falling below that of RF
MIMO. Simulation results validate our analysis and yield practical, closed-form design guidelines for RAQR front ends, revealing parameter regimes in which RAQ-
MIMO outperforms conventional
MIMO systems.
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All authors Qihao Peng, Qu Luo, Tierui Gong, Neng Ye, Jizhou Wu, Cunhua Pan, Maged Elkashlan, Pei Xiao, Chau Yuen, George K. Karagiannidis, Jiangzhou Wang
Image and Video Processing
Learning to Focus Synthetic Aperture Radar On-line with State-Space Models
Sebastian Fieldhouse, Roberto Del Prete, Gabriele Daga et al. (+3 more)
Conventional focusing methods for Synthetic Aperture Radar (SAR) employ block processing efficiently but remain latency-heavy processes that prevent the realisation of a closed-loop cognitive SAR
vision system. We present the first Online SAR Processor (OSP), an online image-formation framework that treats SAR sensing as a stream and produces focused SAR image output line by line during acquisition. OSP uses a tiny state-space surrogate model trained with teacher-student
distillation and multi-stage losses. We evaluate the method on 300GB of SAR data from Maya4, a Sentinel-1-derived
dataset containing raw, range-compressed, range-
cell-migration-corrected, and azimuth-compressed products. Relative to a linewise digital-signal-processing baseline, OSP delivers approximately 70$\times$ lower latency and 130$\times$ lower
memory use; on a single AMD CPU core it processes one row in 16 ms with a
memory footprint of 6 MB whilst maintaining a focusing quality high enough to support downstream decisions, which we illustrate with vessel detection and flood-mapping tasks.
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All authors Sebastian Fieldhouse, Roberto Del Prete, Gabriele Daga, Nathaniel Rensly, Gabriele Meoni, Kea-Tiong Tang
Signal Processing · Cross-listed from cs.AI
CORTEG: Foundation Models Enable Cross-Modality Representation Transfer from Scalp to Intracranial Brain Recordings
Liuyin Yang, Qiang Sun, Bob Van Dyck et al. (+2 more)
Intracranial electrocorticography (ECoG) offers high signal-to-noise access to cortical activity for
brain-computer interfaces, yet limited per-patient data has led most prior work to rely on small, subject-specific decoders that neglect information shared across patients. We investigate whether large pretrained scalp-
EEG foundation models (
EEG FMs) can be adapted to ECoG, enabling cross-patient learning and competitive decoding performance while calibrating to a held-out patient in 10-30 minutes on a single GPU. We introduce CORTEG, a cross-modality transfer framework that combines a pretrained
EEG FM backbone, an electrode-aware KNNSoftFourier spatial adapter, a dual-stream tokenizer for low-frequency and high-gamma activity, and a leave-one-subject-out fine-tuning strategy. We evaluate CORTEG on two challenging regression tasks: public finger-trajectory regression ($n=9$) and private audio-envelope regression ($n=16$). CORTEG achieves state-of-the-art mean performance on both tasks, achieving the highest mean correlation among the compared methods on the public finger
benchmark and larger, statistically significant gains on the audio task and in low-data-per-patient calibration. We further validate CORTEG on the public BrainTreebank stereo-
EEG classification tasks, where it also performs strongly. Furthermore, CORTEG outperforms the compared intracranial-
EEG foundation models across the continuous regression tasks. Feature analyses align with neurophysiology, and latent representations capture low-dimensional finger-movement structure. Together, these results provide systematic evidence that scalp-
EEG pretraining can be repurposed across intracranial recording modalities and tasks, enabling data-efficient neural decoders that can adapt to new patients.
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All authors Liuyin Yang, Qiang Sun, Bob Van Dyck, Eva Calvo Merino, Marc M. Van Hulle
Systems and Control · Cross-listed from cs.IT
Low-Cost GNSS Anti-Jamming Through 2-Bit Phase Shift Beamforming with Machine Learning
Burak Soner, Ekin Uzun and Can Aksoy
We investigate low-cost GNSS anti-jamming using beamforming with inexpensive 2-bit phase shifters, constraining each complex array weight to one of four QPSK phase states (real/imaginary = -1 or +1). This severe quantization sharply limits the beampattern solution space, making conventional real-valued beamforming and naive weight quantization highly suboptimal. We formulate a discrete optimization that trades interference suppression against satellite-direction gain, and
benchmark known combinatorial optimization methods across array sizes and interference conditions. Simulations show that performance improves with array size, with oracle and greedy search achieving up to 34 dB nulling, but oracle incurs exponential latency and greedy sampling is
stochastic. To obtain deterministic low-latency performance, we propose an ML-aided method based on gradient-boosted decision trees followed by local search, which performs similar to the oracle for larger arrays at fixed latency. We further validate the approach experimentally using a fully digital emulation of the QPSK oracle beamformer and compare against a GNSS receiver without beamforming capability. Under mild jamming (J/S approximately 44 dB) both receivers maintain adequate tracking, with QPSK yielding a 4.2 dB higher average C/N0 (37.3 vs. 33.1 dB-Hz). Under moderate and strong jamming (J/S approximately 62-70 dB) the benefit is substantial. At J/S = 70 dB the unprotected receiver degrades to near tracking limits (avg C/N0 = 9.3 dB-Hz) while the QPSK oracle sustains an average C/N0 of 20.8 dB-Hz. These results confirm that 2-bit phase-shift beamforming provides considerable anti-jamming benefit over a standard GNSS receiver, motivating further research on oracle-level practical methods.
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Signal Processing
Unsupervised Online Channel Estimation for High-Mobility OFDM via Implicit Neural Representation
Bohao Shi, Tianfu Qi, Xiaonan Chen et al. (+1 more)
Accurate channel estimation remains challenging in high-mobility wireless systems because Doppler shifts induce severe inter-carrier interference (ICI) in Orthogonal Frequency Division Multiplexing (OFDM). We propose an unsupervised online channel estimation framework based on Implicit Neural Representation (INR). Unlike discrete-grid
estimators, the proposed method decouples channel representation from the OFDM sampling resolution by modeling the time-varying frequency-selective channel as a continuous function of time-frequency coordinates. A Sinusoidal Representation Network (SIREN) with Gaussian
Fourier feature mapping captures fine-grained channel variations and high-frequency details without offline pre-training or labeled data. For each received slot, the network parameters are updated by per-slot online fitting that minimizes a physics-aware ICI loss, while a confidence-aware decision-directed loop balances reliable pilots and dynamically harvested pseudo-pilots. Simulations in realistic Vehicle-to-Everything (V2X) environments show that the proposed method achieves near-optimal link-level reliability, significantly outperforming Least Squares (LS) and robust Linear Minimum Mean Square Error (LMMSE)
estimators. Compared with supervised deep learning baselines, it also exhibits strong out-of-distribution (OOD) robustness under environmental distribution shifts, establishing an adaptable data-efficient physical-layer paradigm.
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All authors Bohao Shi, Tianfu Qi, Xiaonan Chen, Jun Wang
Audio and Speech Processing · Cross-listed from cs.SD
Polyphonia: Zero-Shot Timbre Transfer in Polyphonic Music with Acoustic-Informed Attention Calibration
Haowen Li, Tianxiang Li, Yi Yang et al. (+2 more)
The advancement of
diffusion-based text-to-music generation has opened new avenues for zero-shot music editing. However, existing methods fail to achieve stem-specific timbre transfer, which requires altering specific stems while strictly preserving the background accompaniment. This limitation severely hinders practical application, since real-world production necessitates precise manipulation of components within dense mixtures. Our key finding is that, while vanilla cross-
attention captures semantic features of stems, it lacks the spectral resolution to strictly localize targets in dense mixtures, leading to boundary leakage. To resolve this dilemma, we propose Polyphonia, a zero-shot editing framework with Acoustic-Informed
Attention Calibration. Rather than relying solely on diffuse semantic
attention, Polyphonia leverages a probabilistic acoustic prior to establish coarse boundaries, enabling non-target stems preserved precise semantic synthesis. For evaluation, we propose PolyEvalPrompts, a standardized
prompt set with 1,170 timbre transfer tasks in polyphonic music. Specifically, Polyphonia achieves an increase of 15.5% in target
alignment compared to baselines, while maintaining competitive music fidelity and non-target integrity.
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All authors Haowen Li, Tianxiang Li, Yi Yang, Boyu Cao, Qi Liu
Audio and Speech Processing · Cross-listed from cs.CL
How Should LLMs Listen While Speaking? A Study of User-Stream Routing in Full-Duplex Spoken Dialogue
Hui Lu, Xueyuan Chen, Huimeng Wang et al. (+4 more)
Full-duplex spoken dialogue requires a model to keep listening while generating its own spoken response. This is challenging for large
language models (LLMs), which are designed to extend a single coherent sequence and do not naturally support user input arriving during generation. We argue that how the user stream is routed into the LLM is therefore a key architectural question for full-duplex modeling. To study this question, we extend a text-only LLM into a unified full-duplex spoken dialogue system and compare two routing strategies under a shared training pipeline: (i) channel fusion, which injects the user stream directly into the LLM input, and (ii) cross-
attention routing, which keeps the user stream as external
memory accessed through cross-
attention adapters. Experiments on spoken question answering and full-duplex interaction
benchmarks reveal a clear tradeoff. Channel fusion yields stronger semantic grounding and consistently better question-answering performance. However, under semantically overlapping conditions such as user interruptions, it is more vulnerable to context corruption: if the model fails to stop in time, the overlapping user stream can interfere with ongoing generation and lead to semantically incoherent continuations. Cross-
attention routing underperforms on question answering, but better preserves the LLM generation context and is more robust to this failure mode. These results establish user-stream routing as a central design axis in full-duplex spoken dialogue and offer practical guidance on the tradeoff between semantic integration and context robustness. We provide a demo page for qualitative inspection.
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All authors Hui Lu, Xueyuan Chen, Huimeng Wang, Shuhai Peng, Shiyin Kang, Xixin Wu, Zhiyong Wu
Signal Processing
LO-Free Receiver: Next-Gen Low-Power Joint Communication and Sensing
Hasan Atalay Gunel, Mohaned Chraiti and Ali Gorcin
This paper introduces and analyzes Spatial Phase
Manifold Communications (SPMC), a paradigm that facilitates joint communication and sensing (JCAS) over Local Oscillator (LO) free receiver. Information is embedded in, and recovered from, the relative spatial phase between
antennas. In contrast to conventional coherent receivers that rely on LOs and on channel estimation/equalization, SPMC exploits
antenna-domain correlation to form a baseband observable that is a function of inter-
antenna phase differences. Since these phase differences are fundamentally tied to Direction-of-Arrival (DoA) and vice-versa, the formulation recasts communication and sensing as inference over the unit-circle
manifold and thus naturally supports JCAS decomposition, i.e., data and spatial sensing are encoded and recovered through DoA signatures. We develop a comprehensive framework comprising: (i) a
manifold-domain signal model and corresponding phase-alphabet design; (ii) an LO-free quadrature spatial-correlator receiver architecture that resolves the phase-sign ambiguity without requiring an LO; and (iii) an analysis of error probability and sensing precision, including robustness to phase noise. The proposed paradigm is particularly suited to massive Internet-of-Things (IoT) deployments, for which hardware simplicity, LO distribution cost, power consumption, and seamless sensing integration are critical, especially at millimeter-wave and higher carrier frequencies.
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Systems and Control
Online Learning-Based Control with Guaranteed Error Bounds for a Class of Nonlinear Systems
Ricus Husmann, Sven Weishaupt, Malin Lotta Husmann et al. (+1 more)
In this paper, we present a learning-based control for a class of nonlinear systems that guarantees exponential stability as well as bounded output errors. The control is based on the Gaussian Process Submodel Online Learning (GPSOL)
algorithm and the Disturbance Error Rate Limiting (DERL)
algorithm, both of which were developed in previous work. The GPSOL
algorithm provides a method to learn Gaussian Process (GP) models for subsystems online, whereas the DERL
algorithm allows to limit the rate of the prediction error of these GP models. The focus of this paper is the utilization of the GP model within an adaptive controller and the derivation of corresponding stability conditions and system peak-to-peak gains by means of linear
matrix inequalities (LMIs). These peak-to-peak gains are then used to prescribe a desired prediction error rate for the DERL
algorithm to achieve user-defined output error bounds. The gains and the related bounds were successfully verified using a simulation model. Furthermore, results form a successful experimental validation of the bounds and the overall control structure on a pneumatic test rig are presented. While the control scheme and error bounds proposed in this paper are limited to first-order single-input-single-output systems, an extension to certain classes of higher-order and multiple-input-multiple-output systems is expected to be forthcoming.
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All authors Ricus Husmann, Sven Weishaupt, Malin Lotta Husmann, Harald Aschemann
Systems and Control · Cross-listed from cs.LG
Learning to Sparsify Stochastic Linear Bandits
Zhengmiao Wang, Ming Chi, Zhi-Wei Liu et al. (+2 more)
This paper addresses the problem of learning to sparsify
stochastic linear bandits, where a decision-maker sequentially selects actions from a high-dimensional space subject to a sparsity constraint on the number of nonzero elements in the action vector. The key challenge lies in minimizing cumulative regret while tackling the potential NP-hardness of finding optimal sparse actions due to the inherent combinatorial structure of the problem. We propose an adaptively phased exploration and exploitation algorithmic framework, utilizing ordinary least squares for parameter learning and specialized subroutines for sparse action selection. When the action set is a Euclidean ball, optimal sparse actions can be efficiently computed, enabling us to establish a $\tilde{\mathcal{O}}(d\sqrt{T})$ regret, where $d$ is the dimension of the action vector and $T$ is the time horizon length. For general convex and compact action sets where finding optimal sparse actions is intractable, we employ a greedy subroutine. For general strongly convex action sets, we derive a $\tilde{\mathcal{O}}(d \sqrt{T})$ $\alpha$-regret; for general compact sets lacking strong convexity, we establish a $\tilde{\mathcal{O}}(d T^{2/3})$ $\alpha$-regret, where $\alpha$ pertains to the approximation ratio of the greedy
algorithm. Finally, we validate the performance of our
algorithms using extensive experiments including an application to recommendation system.
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All authors Zhengmiao Wang, Ming Chi, Zhi-Wei Liu, Lintao Ye, Carla Fabiana Chiasserini
Signal Processing
A Generative AI-Enhanced Digital Twin Framework for Proactive Interference Management in Hybrid Near/Far-Field Wireless Systems
Afan Ali, Ali Arshad Nasir and Daniel Benevides da Costa
The applications of Digital Twins (DT) and Generative AI (GenAI) have demonstrated their capabilities in modeling and learning-based wireless communications. However, their joint potential for proactive wireless system design remains largely underexplored, particularly in extremely large-scale multiple-input multiple-output (XL-
MIMO) networks, characterized by hybrid near-field (NF) and far-field (FF) propagation regimes. In this work, we propose an integrated GenAI-enhanced DT framework for proactive interference management in dynamic indoor scenarios. The DT constructs a high-resolution, site-specific virtual replica of the deployment environment, understanding where and why blockage occurs within a realistic 3D representation of the indoor space. Integration of the GenAI module further assists the framework in anticipating and proactively suppressing blockage, rather than reacting after the disruption occurs. Extensive simulation results based on Sionna ray-tracing
datasets demonstrate that the proposed framework achieves significant improvements in interference suppression, signal-to-interference-plus-noise ratio (SINR), and outage probability compared to conventional reactive schemes and purely deterministic DT-based approaches.
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Systems and Control
Transmission Topology Optimization using accelerated MapElites
Nico Westerbeck, Leonard Hilfrich and Dirk Witthaut
Transmission
Topology Optimization has great potential to improve efficiency and flexibility of grid operations through non-costly switching actions, but previous approaches struggle with runtime performance and scalability. In this work, we present an optimization approach that leverages GPU acceleration to speed up computations. In a genetic
algorithm setting,
topologies are randomly mutated and evaluated in parallel for multiple optimization criteria. Combined with a fully GPU-native DC loadflow solver, there is no CPU-GPU data transfer required in the DC optimization loop. Using a variant of the illumination
algorithm MapElites, we efficiently generate a set of diverse candidate solutions on the pareto front. Together with an importing and AC validation step, we present an end-to-end optimization solution that runs in under 15 minutes. The approach is currently under evaluation by operational planning operators in two European TSOs. We furthermore open-source our code at github.com/eliagroup/ToOp.
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Systems and Control
Lure-and-Reveal: An Exposure Framework for Stealthy Deception Attack in Multi-sensor Uncertain Systems
Meiqi Tian, Yihan Liu and Bingzhuo Zhong
Multi-sensor integration via error-state Kalman filter (KF) is widely employed for precise state estimation in cyber-physical systems (CPSs). However, this integration exposes the system to stealthy deception attacks that render conventional detection mechanisms ineffective. We propose an exposure framework to actively reveal such stealthy attacks without modifying sensor interfaces. The framework introduces a suspect mode in which the defender injects random exposure shakes into the nominal control inputs, thus creating a discrepancy between the defender's true state estimates and the attacker's manipulated state estimates, preventing the attack from remaining stealthy. We further derive an explicit exposure condition that characterizes the minimum shake magnitude to guarantee the finite-time exposure and a compensable condition that ensures the shakes do not degrade closed-loop performance. Simulation results based on a GNSS/INS-integrated
UAV system verify the effectiveness of the proposed framework.
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Systems and Control · Cross-listed from cs.NI
Learning to Compress and Transmit: Adaptive Rate Control for Semantic Communications over LEO Satellite-to-Ground Links
Jiangtao Luo, Yongyi Ran, Guoliang Xu et al. (+1 more)
The bottleneck of satellite-to-ground links poses a major challenge for the timely downlink of massive on-board imagery. This paper studies adaptive image transmission over LEO satellite-to-ground links using joint source-channel coding (JSCC). We propose an RL-based framework that dynamically selects the channel dimension (compression ratio) of a SwinJSCC encoder to maximize the number of received satisfying reconstruction-quality constraints (PSNR and MS-SSIM) within a finite visibility window. The
agent leverages SNR prediction to perform proactive rate adaptation and incorporates an on-board transmission-queue model that captures bursty encoding while penalizing both buffer overflow and underutilization. Simulations under realistic overpass conditions show that the proposed policy substantially outperforms fixed-rate baselines, achieving nearly 95% qualified frames with zero packet loss.
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All authors Jiangtao Luo, Yongyi Ran, Guoliang Xu, Jihua Zhou
Audio and Speech Processing
PoDAR: Power-Decoupled Audio Representation for Generative Modeling
Alejandro Luebs, Mithilesh Vaidya, Ishaan Kumar et al. (+5 more)
The performance of audio latent
diffusion models is primarily governed by generator expressivity and the modelability of the underlying latent space. While recent research has focused primarily on the former, as well as improving the reconstruction fidelity of audio codecs, we demonstrate that latent modelability can be significantly improved through explicit factor decoupling. We present PoDAR (Power-Decoupled Audio Representation), a framework that utilizes a randomized power augmentation and latent consistency objective to decouple signal power from invariant semantic content. This factorization makes the latent space easier to model, which both accelerates the convergence of downstream generative models and improves final overall performance. When applied to a Stable Audio 1.0 VAE with an F5-TTS generator, PoDAR achieves about a 2x acceleration in convergence to match baseline performance, while increasing final speaker similarity by 0.055 and UTMOS by 0.22 on the LibriSpeech-PC
dataset. Furthermore, isolating power into dedicated channels enables the application of CFG exclusively to power-invariant content, effectively extending the stable guidance regime to higher scales.
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All authors Alejandro Luebs, Mithilesh Vaidya, Ishaan Kumar, Sumukh Badam, Stephen W. Bailey, Matthew Bendel, Jose Sotelo, Xingzhe He
Image and Video Processing
Polarization-Aware Ray-Tracing Enhanced Back-Projection Algorithm for Microwave Imaging in Complex Multipath Environments
Han Na, Quanfeng Wang, Matthias Saurer et al. (+2 more)
A ray-tracing (RT) enhanced back-projection
algorithm (RT-BPA) for microwave imaging in multipath environments is presented. By tightly incorporating the concept of ray-tracing into a generalized version of traditional BPA, this method ensures improved image quality by addressing two important issues. First, when the line-of-sight (LOS) path is obstructed, reflected paths, if available, enable imaging of hidden targets, which extends the applicability of the standard BPA beyond its normal use case. Second, the consideration of reflected ray-paths is equivalent to virtually increasing the aperture size, thus, improving image resolution without requiring new measurements. A key factor in achieving these advancements is the consideration of the vector nature of electromagnetic waves with polarization-dependent phase compensation, which is often ignored when employing a scalar-wave based formulation of the electromagnetic vector field. In addition, the presented method employs a shooting and bouncing rays (SBR) framework, offering better flexibility compared to manual path evaluation in existing RT-BPAs.
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All authors Han Na, Quanfeng Wang, Matthias Saurer, Meisong Tong, Thomas F. Eibert