Signal Processing
Compressed LLM Reprogramming for Vision-Aided Beam Prediction in Vehicular Networks
Kai Dong, Lei Wang, Changyi Li et al. (+2 more)
Large
Language Model (LLM) reprogramming-based beam prediction demonstrates strong data efficiency by adapting pretrained
language models for vehicle-to-infrastructure (V2I) beam prediction, yet the resulting model complexity makes such approaches impractical for latency-sensitive deployment. We propose LLMBP-Lite, a compact LLM-reprogrammed framework for beam prediction. It leverages structural redundancy through
pruning along three complementary dimensions:
Transformer depth, source-prototype vocabulary size, and
prompt length. Additionally, knowledge
distillation can be optionally employed to maintain the pretrained representational capacity after compression. Experiments on the real-world
dataset demonstrate that LLMBP-Lite achieves a $65\times$ inference speedup over the uncompressed LLM-based baseline while maintaining prediction accuracy and consistently outperforming recurrent baselines under limited training data. These results demonstrate that the tradeoff between data efficiency and deployment efficiency can be substantially mitigated in vehicular networks.
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All authors Kai Dong, Lei Wang, Changyi Li, Sergiy A. Vorobyov, Stefan Werner
Systems and Control · Cross-listed from cs.LG
Manifold-Stable Flow Matching
Amirhossein Nazerian, Ali Pezeshki and Jianguo Zhao
Flow matching (FM) learns generative dynamics through velocity regression.
Geometric FM variants commonly assume a prior supported on the data
manifold, requiring
geometric knowledge that is often unavailable. Without such knowledge, low regression error alone does not guarantee
manifold adherence. Adherence keeps generated samples within valid configurations and is empirically associated with better task performance. We introduce
manifold-stable flow matching (MSFM), which can start from an arbitrary ambient prior, not necessarily supported on the
manifold. Using tools from nonlinear dynamics, namely contraction theory, MSFM combines learned tangential transport with prescribed normal contraction. The construction uses analytical projectors for known
manifolds and local affine proxies estimated by principal component analysis for unknown data geometry. By implementing contraction theory in both cases of known and unknown
manifolds, we guarantee
manifold invariance and transverse convergence to the
manifold within a desired time window (e.g., one second). We derive a family of compatible probability paths and decompose the training loss into a learnable tangential term and a normal residual. An ellipse experiment attains a mean terminal off-
manifold error of order $10^{-6}$. In Push-T robotic experiments, MSFM raises success from $74\%$ to $82\%$. In the Robomimic Square task, success increases from $60\%$ to $72\%$, while rotation-
manifold deviation decreases from order $10^{-2}$ to $10^{-7}$. The MSFM terminal
geometric errors are controlled by the chosen numerical tolerance. These results demonstrate stronger
geometric adherence and higher observed task performance, supporting prescribed normal contraction as a complement to learned generative transport.
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Systems and Control
Scalable Small-Signal Stability Assessment of Power Systems Based on Frequency-Domain Quadratic Constraints
Xiaoying Liu, Linbin Huang, Hangyu Chen et al. (+1 more)
Small-signal stability analysis of power electronics-dominated power systems is becoming increasingly challenging due to the large-scale integration of heterogeneous grid-following (GFL) and grid-forming (GFM) converters. Classical centralized methods, such as
eigenvalue analysis and the generalized Nyquist criterion, provide direct stability assessment tools but exhibit limited scalability as the system size increases. This motivates scalable analysis methods for stability assessment and device-level diagnosis, and calls for less conservative stability conditions. To this end, this paper proposes a scalable small-signal stability assessment method with quantitative stability indices for multi-converter systems based on frequency-domain quadratic constraints (FQCs). It is shown that several existing stability conditions, including
geometric conditions based on the Davis-Wielandt (DW) shell, numerical range, $x$-$z$ graph, scaled relative graph (SRG), mixed gain-phase condition, and passivity condition, are special cases of the FQC-based stability condition. This FQC-based formulation also clarifies the requirements for decentralized verification of these existing stability conditions. To further reduce conservatism, a full-multiplier FQC-based stability condition is developed, based on which an optimization problem is formulated for scalable stability certification and device-level diagnosis using quantitative stability indices without relying on graphical inspection. Combined with the mixed gain-phase condition, this optimization problem forms a hierarchical screening-diagnosis procedure that improves efficiency. Case studies demonstrate that the proposed method is less conservative than existing criteria and can effectively identify problematic devices associated with potential instability risks.
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All authors Xiaoying Liu, Linbin Huang, Hangyu Chen, Huanhai Xin
Systems and Control · Cross-listed from cs.RO
Adaptive Safety Filtering for Frozen ACC Policies via Conformal Residual Calibration
Zhiruo Zhou, Rigaudiere Z. Li, Chen Xiwen et al. (+3 more)
Frozen adaptive cruise control (ACC) policies can violate constraints when deployment dynamics differ from their training conditions. We propose residual-aware conformal action filtering (RACF), which calibrates residuals of a fixed nominal predictor and converts their
quantile into an operating margin for finite-model action projection. Completed transitions update margins and candidate selection without retraining the policy. In a registered comparison over 2,400 controller-trial units, Adaptive RACF achieves 94.3% episode safety, improving by 19.9 percentage points over the evaluated nominal CBF-QP baseline while reducing projection frequency from 8.11% to 6.63%. A controlled study isolates a 4.54-point improvement from residual-margin injection. In a separate matched-hardware evaluation, Adaptive reduces mean amortized rollout time by 21.2% relative to Robust CBF-QP, with 161/180 versus 170/180 safe episodes. We characterize conditions linking one-step residual coverage to constraint satisfaction and quantify the observed safety-computation trade-offs.
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All authors Zhiruo Zhou, Rigaudiere Z. Li, Chen Xiwen, Yucheng Chen, Xiaojun Zhu, Houde Liu
Signal Processing
Adapting offline models to a streaming context for music source separation
Dylan Sechet, Marc Evrard and Matthieu Kowalski
Real-time music source separation must satisfy two constraints: a bound on algorithmic latency and a bound on computational cost. Offline separators are usually omitted from real-time comparisons or credited with a latency equal to their full input length. We show that this latency is set by where the output is read, not by the length of the separator's input. An unmodified offline model can therefore run in a streaming setting, without retraining. At each step, the input slides by one STFT hop, and one output hop is read out. The resulting latency can be as low as one STFT hop (23 ms), and the computational cost does not increase as latency shrinks. We identify a theoretical model-dependent latency boundary below which separation quality should drop steeply, and confirm this experimentally across three architectures. At equal algorithmic latency, streamed off-the-shelf checkpoints for HT-Demucs and SCNet match the published results of dedicated real-time models in terms of separation quality. Streamed models remain far less computationally efficient: only HT-Demucs runs faster than real time on a GPU.
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Systems and Control · Cross-listed from cs.AI
Jev thinks "I don't know”, but doesn't say it: Introducing Sys1Cal-v1 Dataset for Probability Calibration
Riccardo Porcedda
The appearance of Jev marked the era of System One Models, foundation models that return structured decisions with probability distributions rather than text. Aside from low cost and great speed, Jev's central promise is that these probabilities are calibrated: such claim is not backed by any public test and available external
benchmarks evaluate confidence calibration, not whether every returned option probability has the right numerical meaning. To tackle this issue, we introduce Sys1Cal-v1, a
dataset of True/False questions about a proposition $A$ for which the exact probability $P(A)$ is known by construction. Each item is queried through the three Jev primitives - Noul, Choice and Score - and evaluated by total variation distance from the ground-truth distribution, which can be used to estimate a soft accuracy of System One Models. We showcase the utility of Sys1Cal-v1 as a
benchmark dataset by evaluating Jev and SemIf, an open-source Choice-style baseline. In this work, however, we focus even more deeply on Jev, by studying the calibration of its Score and Choice answers. In particular, we discover a peculiar behaviour that can be explained by assuming that Jev suppresses a third truth value, going beyond True and False. In other words, in Choice answers, $P(A)$ and $P(\neg A)$ are presented as if $P(A)+P(\neg A)=1$, while a term $P(U)\neq0$ is missing in the sum. Recovering $P(U)$ leads to an improvement of median soft accuracy in Choice answers from $0.771$ to $0.978$, suggesting that, even in binary decisions, Jev wants to answer with a third option:“I don't know”.
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Audio and Speech Processing
Simulation-Based Inference for Plate Reverb System Identification
Dylan Sechet, Marc Evrard and Matthieu Kowalski
We address Task A of the 1st DAFx Parameter Estimation Challenge, which aims to retrieve the physical parameters of a plate model from an impulse response. To do so, we use the Simulation-Based Inference (SBI) framework, in which we train a neural network to estimate a density over plate parameters given an impulse response, using a
dataset generated by the simulator. Inference for a new impulse response then requires only a forward pass through the network, without involving the simulator. For each test observation, we fine-tune a specific network: additional simulation rounds are performed by sampling parameters from the current estimated distribution, simulating the corresponding impulse responses, and fine-tuning to produce the specialized network.
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Systems and Control
Hard-Constrained Probabilistic Factor Graph Neural Network for Distribution System State Estimation under Non-Gaussian Uncertainty
M. Furqan Azam, Marta Vanin, Chris Hermans et al. (+1 more)
Robust and accurate state estimation is fundamental for the reliable operation and monitoring of active distribution networks. Conventional numerical
estimators, such as weighted least squares, are computationally slower and often suffer from convergence issues in the presence of sparse measurements affected by non-Gaussian noise. Physics-informed neural networks have recently emerged as a promising alternative by incorporating physical principles through residual-based penalty terms in the objective, which can improve robustness to noise and computational efficiency. However, such penalty-based approaches do not guarantee strict enforcement of physical constraints during inference and provide limited support for principled uncertainty modeling. To address these limitations, we propose a novel Hard-Constrained, Physics-Informed Factor Graph Neural Network (HCP-PINN) that formulates distribution system state estimation as a probabilistic constrained estimation problem on a factor graph. The proposed approach explicitly models non-Gaussian (pseudo-)measurement uncertainty through flexible, closed-form likelihood-based loss functions. It further incorporates a differentiable optimization-based estimation layer that strictly enforces nonlinear equality constraints and measurement consistency, producing physically feasible state estimates during both training and inference. To the best of our knowledge, this is the first PINN-based DSSE framework to combine hard physical constraints with non-Gaussian uncertainty modeling for unbalanced three-phase networks. Numerical experiments demonstrate that the proposed method delivers more accurate and physically consistent state estimates than deep learning
benchmarks and numerical
estimators, while exhibiting greater robustness to network model errors and improved computational efficiency under realistic measurement scenarios.
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All authors M. Furqan Azam, Marta Vanin, Chris Hermans, Geert Deconinck
Signal Processing
Multiresolution Block-Coordinate Plug-and-Play Algorithm for Image Reconstruction
Edgar Desainte-Maréville, Marion Foare, Paulo Gon{\c c}alves et al. (+2 more)
Plug-and-Play methods are among the state-of-the-art approaches for image reconstruction, but they do not scale well with the image size. We propose a multiresolution block-coordinate Plug-and-Play
algorithm that decomposes the image into wavelet blocks and applies a block-wise denoiser network to only a subset of blocks at each iteration, selected through a
stochastic Gauss-Southwell-inspired activation rule. Numerical results on deblurring show that the proposed method outperforms the standard Plug-and-Play in different degradation regimes, and in particular the adaptive rule dynamically adjusts to the degradation regime to match the optimal activation rule in every context.
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All authors Edgar Desainte-Maréville, Marion Foare, Paulo Gon{\c c}alves, Nelly Pustelnik, Elisa Riccietti
Signal Processing
EMA-Based Subspace Tracking for Adaptive Artifact Subspace Reconstruction
Vishnu KN and Cota Navin Gupta
Electroencephalogram (
EEG) artifact removal remains a critical challenge for real-world
brain-computer interface deployment due to non-stationary signal statistics and limited calibration availability. Artifact Subspace Reconstruction (ASR) provides an automated framework for variance-based artifact suppression but relies on a static calibration-derived covariance model, limiting stability under intra-subject drift and increasing sensitivity to parameter mis-specification. This work proposes an adaptive ASR framework based on exponential moving average (EMA) subspace tracking. By integrating short-horizon covariance estimation with slow recursive assimilation, the method establishes dual adaptation timescales that enable responsiveness to evolving
EEG structure while preserving stability against transient artifacts. This formulation further promotes smoother operating characteristics across rejection thresholds, reducing sensitivity to hyperparameter selection in continuous deployment settings. Evaluated on 24-channel
EEG recordings from 10 subjects with prominent blink artifacts across cognitive states, EMA-ASR achieved substantially stronger artifact attenuation than Original and
memory-limited ASR variants (53.1% vs. 24.0% and 26.7% blink reduction), at the cost of increased reconstruction and spectral deviation, whereas the
memory-limited variant performed comparably to Original ASR. These findings position EMA-based adaptive tracking as a lightweight, deployment-oriented approach to continuous
EEG artifact removal under non-stationary conditions, with an explicit trade-off between suppression strength and signal preservation.
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Signal Processing
Finite-Resolution Microwave Linear Analog Computer (MiLAC)-Aided Multiuser Beamforming
Zheyu Wu and Bruno Clerckx
Large-scale
antenna arrays are essential to future wireless networks but impose significant hardware and digital-processing burdens. The microwave linear analog computer (MiLAC) offers a promising architecture for addressing these challenges. In a MiLAC, beamforming is realized entirely in the analog domain through a reconfigurable multiport microwave network comprising tunable admittance elements. However, existing studies assume that these elements are continuously tunable, whereas practical implementations can support only finitely many configurable states. This paper investigates finite-resolution MiLAC-aided multiuser beamforming under lossless and reciprocal constraints with prescribed connectivity patterns. Each tunable susceptance is selected from a symmetric uniform finite-resolution codebook. We formulate an online problem that jointly optimizes the discrete susceptances and power allocation for a prescribed codebook, and an offline problem that designs the codebook based on channel statistics. By exploiting the odd-uniform codebook structure, we express each multilevel susceptance as a weighted sum of two-level variables and develop exact continuous penalty models for both the online beamforming and offline codebook design problems. We prove that, for sufficiently large penalty parameters, these penalty models are globally equivalent to their original discrete counterparts. Building on these formulations, we develop efficient ADMM-based
algorithms for solving the two problems. Numerical results demonstrate that the performance of an unquantized fully-connected MiLAC can be approached with substantially reduced connectivity and finite resolution. In particular, a 3-bit stem-connected MiLAC achieves more than 95% of the sum-rate performance of the unquantized fully-connected MiLAC while requiring only 22% of its tunable components.
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Systems and Control
Strategically Robust Game-Theoretic Multi-Agent Trajectory Optimization
Victor L. Qin, Nicolas Lanzetti, Saverio Bolognani et al. (+1 more)
Aviation authorities worldwide expect Advanced Air Mobility (AAM) traffic management to be decentralized among service providers, requiring AAM flights to autonomously plan trajectories by predicting other flights' control inputs rather than relying on centralized coordination. Game-theoretic approaches that formulate multi-
agent collision avoidance as an exact dynamic potential game can efficiently find open-loop
equilibria, but they assume that
agents exactly follow their
equilibrium trajectories—an unrealistic assumption given uncertainties in actuation, perception, and computation. We propose a strategically robust formulation where each
agent protects against a fictitious adversary that, for each timestep, perturbs other
agents' control inputs within a bounded budget to minimize distance at that timestep. We show that, under reasonable assumptions on
agents' distance cost and robustness levels, the strategically robust game remains an exact dynamic potential game and admits a quasi-closed-form solution to the inner
adversarial problem for linear dynamics, which limits computational overhead. Experiments with up to eight
agents using logarithmic distance costs show that strategic robustness selects more robust trajectories in high-collision-risk configurations while leaving low-risk trajectories nearly unchanged, with only a modest increase in runtime.
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All authors Victor L. Qin, Nicolas Lanzetti, Saverio Bolognani, Hamsa Balakrishnan
Systems and Control
Two-Timescale Reinforcement Learning for Real-Time Optimization and Economic NMPC: Experimental Validation
Saket Adhau, Jose Matias, Sebastien Gros et al. (+1 more)
We propose a reinforcement learning (RL) framework that tunes both Real-Time Optimization (RTO) and Economic Nonlinear Model Predictive Control (ENMPC) to address plant–model mismatch in process systems. Drawing on modifier-adaptation concepts, the method parameterizes the dynamic model, stage costs, constraints, and RTO modifiers, and uses Q-learning to adjust these parameters at two timescales: a fast update for the ENMPC layer and a slow update for the RTO layer. The framework is experimentally validated on a laboratory rig emulating a three-well subsea oil-production network. Using plant measurement data, the proposed RTO-RLMPC scheme achieves 8.6% higher economic profit than nominal ENMPC, preserves input feasibility of the deployed ENMPC policy and empirically satisfies the path constraints under disturbances and measurement noise, and drives the learned model parameters toward reference plant values, independently identified from experimental data, along the directions that most affect the economic objective. This work provides one of the first experimental demonstrations of RL-tuned ENMPC integrated with RTO.
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All authors Saket Adhau, Jose Matias, Sebastien Gros, Sigurd Skogestad
Image and Video Processing
Memory- and Bandwidth-Efficient SPAD-LiDAR Ranging via Coarse-to-Fine Spline Sketching
Zhenya Zang, Istvan Gyongy and Mike Davies
This work presents an optimized compression framework for direct time-of-flight (dToF) light detection and ranging (
LiDAR), using an accurate, compact timestamp-encoding strategy to address the high data-rate bottleneck from single-
photon timing information in single-
photon avalanche diode (SPAD) arrays. We propose a hardware-friendly timestamp-to-depth framework in which a sparse single-
photon encoding strategy, namely coarse-to-fine spline sketches (CFSS), projects
photon timestamps into fine-grained, low-dimensional representations, called sketch values. CFSS converts timestamps on-the-fly to sketch values and accumulates them with lower
memory consumption, without constructing histograms, thereby saving on-chip/device
memory. CFSS's closed-form solution for ToF
retrieval ensures iteration-free reconstruction. Compared with the conventional sketched-
LiDAR framework, the proposed method retains the same compression ratio in the single-peak case, ranging from hundreds$\times$ to thousands$\times$ depending on the accuracy-complexity trade-off, while improving depth-estimation accuracy. Both synthetic and real
datasets are used to validate the performance. The CFSS framework is further extended to two-peak scenarios, enabling recovery of objects obscured by partially occluding camouflage and uniformly scattering semi-transparent media. Firmware implementation is also investigated by clearly separating online hardware processing from offline software workloads.
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Signal Processing · Cross-listed from cs.LG
A Multimodal Autonomic Sensing Framework for Objective Assessment of Patient Responses to Dental Pulp Stimulation
Youngsun Kong, Yubin Choi, Dongjin Song et al. (+3 more)
Patient responses to dental pulp testing, ranging from no sensation to intense pain, provide important information for assessing pulp status in endodontic diagnosis. However, pain is a subjective sensory and emotional experience that varies considerably across individuals and can be difficult to communicate. We investigated whether complementary autonomic signals could support objective assessment of responses during dental examination. Forty-nine patients underwent cold pulp testing, yielding no-response, mild-response, and intense-response conditions. The framework integrated ECG-derived skin nerve activity (SKNA) and R-R intervals (RRI), together with electrodermal activity (EDA), using temporal convolutional network encoders with
attention-based mid-level fusion. Individual baseline signals and subject-level
covariates, including anxiety scores and biological sex, were also incorporated. The framework achieved 80.2% balanced accuracy, 75.2% sensitivity, and 85.2% specificity for binary classification of no response versus mild or intense response. For three-class classification, it achieved 60.0% balanced accuracy and a 58.8% macro-averaged F1 score. Ablation and
attention-weight analyses indicated that EDA contributed most strongly to model performance, followed by RRI, while SKNA improved balanced accuracy by approximately five percentage points. Age was significantly associated with model performance. These findings support the feasibility of
multimodal autonomic sensing for objective, non-invasive assessment of responses to dental pulp stimulation.
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All authors Youngsun Kong, Yubin Choi, Dongjin Song, Dong-Guk Shin, I-Ping Chen, Ki Chon
Audio and Speech Processing
Perceptual Quality Loss or Loss of Perceptual Quality?
Danilo de Oliveira, Tal Peer, Maurício do V. M. da Costa et al. (+1 more)
Contemporary deep
speech enhancement (SE) models are often trained with specific auxiliary terms in the loss function as a way to improve their performance in terms of perceptual metrics. Nevertheless, a higher score on a perceptual metric does not necessarily correlate with an improved listening experience. Through objective and subjective experiments, we assess the performance of SE models trained with two different types of auxiliary PESQ loss terms. The numerical evaluation on a suite of standard metrics suggests that, while models optimized for PESQ naturally obtain higher PESQ scores in the test set, for most other metrics the scores do not significantly change. In some cases, the PESQ loss even results in worse PESQ scores on mismatched data. A formal listening experiment reveals that the models without a PESQ loss were generally preferred over models that include it, across all settings. Finally, we analyze the relative importance of PESQ in the composite metrics CSIG, CBAK and COVL, and find that PESQ dominates all of them. Our study highlights the perils of over-reliance on PESQ and stresses the importance of a complete evaluation procedure for SE.
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All authors Danilo de Oliveira, Tal Peer, Maurício do V. M. da Costa, Timo Gerkmann
Systems and Control · Cross-listed from math.OC
Amortized Feedback Planning: Turning Model-Based Rollouts into Executable Policies
Jeonggyu Huh
Closed-loop planning accounts for future observation-dependent actions but can be expensive to repeat at deployment. Bellman-gradient (BG) refinement differentiates conditional rollouts through an existing actor, corrects the current action, and stores the result in an executable policy. A backward sweep reuses deployed future feedback; full-horizon rollouts in an identified Gaussian belief model need no learned value critic. A nonlinear error recursion links quadratic continuation error, local correction, and policy storage. A controlled non-LQG example exhibits second-order policy accuracy with consistent storage, while ideal affine LQG admits exact backward recovery. In nonquadratic thrust, BG reduces actor cost by 2.47-3.20% and remains within 0.13-0.53% of the tested feedback MPC; original policies execute in 5-6 microseconds in a seed-0 native audit. With matched storage, BG attains competitive plant costs at about one ninth (arm) and one sixtieth (docking) of feedback-teacher-plus-student construction time on one GPU, excluding shared learning and node preparation. Richer common maps substantially narrow some student-BG gaps. These results expose the roles of learned feedback, local correction, and storage in executable control.
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Signal Processing
User Association and Transmit Beamforming for Rotatable Antenna-Enabled LAE Networks
Bowen Yao, Chao Zhang and Ying-Chang Liang
This paper investigates rotatable
antenna (RA)-enabled low-altitude economy (LAE) networks, where multiple base stations (BSs) are deployed to serve both terrestrial and aerial users. Unlike conventional fixed orientation
antennas, RAs can adjust their boresights to serve users at diverse azimuth and elevation angles, thereby providing three-dimensional (3D) coverage. To improve the performance of LAE networks, we formulate a network sum-rate maximization problem that jointly optimizes user association, transmit beamforming, and RA orientations. However, in such LAE networks, aerial users are often visible to multiple BSs through line-of-sight (LoS) links, making user association and interference management particularly challenging. Moreover, user association and RA orientations are closely coupled: user association affects the RA pointing directions, while the RA orientations in turn reshape the channel conditions for user association. To solve this problem, we propose an alternating optimization (AO)
algorithm that integrates weighted minimum mean-square error (WMMSE) for transmit beamforming, projected gradient ascent updates for user association, and Frank-Wolfe updates for RA orientations. Furthermore, we develop a discrete candidate-scanning scheme that replaces continuous orientation optimization with a finite search to reduce computational complexity. We also propose an
antenna block-based scheme to reduce the number of orientation variables. Simulation results show that the proposed joint design achieves a higher sum-rate than the fixed
antenna orientation and nearest BS association
benchmarks. Moreover, the candidate-scanning and block-based schemes achieve approximately 89.9% and 94.3% of the performance with high transmit power, respectively, while reducing the complexity of orientation updates.
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Signal Processing
LIVE-RIS: A Comprehensive In-Flight Dataset for UAV-Mounted RIS Channel Measurements
David Müller, Kevin Weinberger, Aydin Sezgin et al. (+1 more)
The dynamic control of the wireless propagation environment enabled by reconfigurable intelligent surfaces (RISs) makes them a promising technology for sixth-generation (6G) wireless networks. Beyond conventional fixed-position deployments, integrating a RIS with an unmanned aerial vehicle (
UAV) provides additional spatial flexibility, facilitating favorable Line-of-Sight (LoS) conditions and broadening the range of potential applications. Although
UAV-mounted RIS systems have attracted significant research interest, existing studies rely predominantly on numerical simulations and often overlook the impact of practical constraints and real-world disturbances. To address this gap, the authors recently presented the first
UAV-mounted RIS prototype and experimentally validated its feasibility through real-world experiments. By using the
UAV's extended Kalman Filter (EKF) for real-time RIS reconfiguration, the proposed system effectively mitigates disturbance effects and preserves the performance gains of the RIS-enabled link. To further advance
UAV-mounted RIS research and facilitate broader access to real-world experimental insights, this work provides a comprehensive
dataset collected from multiple flight experiments. The
dataset includes EKF state estimates, ground-truth measurements, corresponding RIS configurations, and S21 channel data.
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All authors David Müller, Kevin Weinberger, Aydin Sezgin, Martin Mönnigmann
Signal Processing · Cross-listed from cs.LG
Cyclostationary Phase Conditioning for Medical Time Series Diffusion
Samuel Ruiperez-Campillo, Michele Copetti, Jorge da Silva Goncalves et al. (+3 more)
Many physiological time series, such as cardiac and
brain recordings, exhibit cyclostationarity: their statistics vary periodically with an underlying cycle phase. Corruption from motion, poor contact, and physiological interference obscures morphology needed for diagnosis, making signal restoration essential. Existing
diffusion approaches condition on corrupted observations alone and must learn cyclic structure implicitly. We instead propose two inductive biases which encode cyclostationarity: a shift-covariant wavelet representation and dense per-sample phase conditioning inferred from the corrupted input. We further introduce a training-free cyclostationarity index that quantifies phase structure and predicts when phase conditioning will help. Finally, we propose antithetic coupling of reverse trajectories to reduce sampling variance while achieving comparable performance with fivefold fewer network evaluations. Across modalities, our results show that explicitly encoding measurable cyclic structure improves physiological time-series restoration.
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All authors Samuel Ruiperez-Campillo, Michele Copetti, Jorge da Silva Goncalves, Sonia Laguna, Thomas Hofmann, Julia E. Vogt
Systems and Control · Cross-listed from math.OC
Predictor-Based Stabilization of a Delayed Hetero-Dimensional Shoreline–Bathymetry System
Amadou Cissé and Mohamed Boutayeb
Exponential stabilization is investigated for a hetero-dimensional parabolic system in which a one-dimensional shoreline subsystem, subject to a constant input delay, is bidirectionally coupled with unactuated two-dimensional bathymetric dynamics. A spectral decomposition separates the finite-dimensional critical shoreline modes from the exponentially stable residual dynamics. State feedback is designed on the critical subspace and lifted to the full shoreline space. An auxiliary transport equation represents the delay, while a predictor removes the explicit input delay from the nominal predictor dynamics. Exponential stability of the full coupled system is established by combining shoreline stabilization and bathymetric coercivity using weighted input–output estimates and a small-gain condition on the hetero-dimensional interaction. Numerical simulations show that uncompensated delayed feedback can strongly amplify both shoreline and bathymetric responses, whereas predictor compensation restores decay of the critical shoreline dynamics and prevents delay-induced amplification from propagating to the unactuated bathymetric subsystem.
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Audio and Speech Processing · Cross-listed from cs.SD
JazzSAMBA: A Synchronous and Asynchronous Multi-take Band Audio Dataset of Jazz Standards for Live Music Models
Phillip Long, Jacob Nguyen, Jace Hosto et al. (+9 more)
Machine learning has made strong progress on music tasks, both as assistive tools and as creative partners. However, most systems train on multitrack corpora that emphasize pop and rock. Jazz, with improvisation at the core of its practice, still lacks a well-annotated corpus of clean per-stem combo recordings on standards. We introduce JazzSAMBA (Jazz Synchronous and Asynchronous Multi-take Band Audio) to fill this gap: the first originally recorded jazz-combo multitrack
dataset of standards with asynchronous (overdubbed) and synchronous (live ensemble) protocols, preferred and alternate takes chosen by the musicians, and timed annotations for bars, chords, sections, and soloists. JazzSAMBA covers 76 standards by eight musicians on drums, bass, piano, trumpet, and saxophone, with per-stem audio, mixtures, and MIDI. It can support chart-conditioned accompaniment, combo source separation, and form-aware music information
retrieval. We demonstrate the
dataset on two tasks: a jazz combo source-separation baseline and a chart-conditioned accompaniment ablation. The
dataset, code, and samples are linked from the project demo page.
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All authors Phillip Long, Jacob Nguyen, Jace Hosto, Gage Hosto, Jett Takazawa, Fares Nofal, Sebastian Stade, Nithya Shikarpur, Julian McAuley, Cheng-Zhi Anna Huang, Stephen Brade, Aleksandra Teng Ma
Audio and Speech Processing
Domain-Incremental Learning for Generative Speech Enhancement
Manjunath Mulimani, Annamaria Mesaros, Minje Kim et al. (+1 more)
We propose a domain-incremental learning framework for generative
speech enhancement (SE) that learns from a sequence of
datasets or domains recorded under diverse acoustic conditions. Fine-tuning a pretrained model on continuously evolving domains leads to catastrophic forgetting of previously acquired knowledge, while zero-shot generalization often fails to adequately adapt to unseen domains. To address these challenges, we first develop a novel
language model-based generative SE model that we then use as a pretrained backbone and incrementally adapt it to acoustically mismatched domains using lightweight domain-specific Low-Rank Adaptation. The proposed framework enables the model to acquire enhancement capabilities for new domains while preserving performance on previously learned domains. Evaluated on four heterogeneous
speech datasets, our approach effectively adapts to new domains without forgetting previously learned domains.
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All authors Manjunath Mulimani, Annamaria Mesaros, Minje Kim, Jesper Rindom Jensen
Signal Processing
HiCoMAC: Histogram-State Coded Multiple Access Computing via Computation-Oriented Modulation Design
Xiaojing Yan and Carlo Fischione
Nowadays, over-the-air computation (AirComp) exploits the waveform superposition property of the wireless multiple access channel to directly compute a function of distributed data from simultaneously transmitted signals. In this paper, we propose Histogram-State Coded Multiple Access Computing (HiCoMAC), a fundamentally new convolutional-coded method for digital AirComp that directly recovers the arithmetic-sum sequence from the superposition of coded and modulated user signals. HiCoMAC exploits the permutation invariance of the sum function to represent the multi-user convolutional encoder state by the numbers of users occupying the individual encoder states. This central idea enables log-max maximum a posterior (MAP) histogram-state Viterbi decoding with substantially reduced state complexity compared to joint full-state decoding. We further introduce the computational free distance to distinguish histogram paths that produce different arithmetic-sum sequences and develop a weighted product graph for its shortest path evaluation. This distance is then used to optimize the rectangular ratio of a fixed labeled quadrature amplitude modulation (QAM) constellation to improve the computational accuracy. Simulation results show that the computation-oriented modulation design increases the computational free distance and reduces the normalized mean square error (NMSE), while HiCoMAC outperforms the considered multi-symbol digital AirComp baselines under equal transmission and energy budgets.
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Signal Processing · Cross-listed from cs.LG
Separating personal from population gains when calibrating EEG foundation models for new users
Xilin Tao and Kani Chen
Foundation models are increasingly adapted to individual users, but an apparent personalization gain can simply reflect a stronger population model. This distinction matters for
brain-computer interfaces, where every new user must be calibrated. We evaluated personal adaptation of three frozen
EEG foundation models (CBraMod, REVE and LaBraM) in 235 held-out subjects from three motor-imagery
datasets, comparing each subject's adapter with the population model and with adapters fitted to other subjects. Using all first-half session labels, personal adapters improved mean balanced accuracy over the population model by 1.5-5.4 percentage points and outperformed exchanged adapters by 2.3-7.3 points in all nine model-
dataset combinations. The size of this benefit depended on population training: with four times the original budget, median gains remained positive (1.0-2.0 points) but were smaller for every model, and no population model reached a confirmed plateau. Acquiring the benefit cheaply was unreliable: few-label calibration was consistently non-negative on only one
dataset, and in CBraMod neither unlabeled context nor meta-learned initialization outperformed matched controls. Personalization should therefore be evaluated against both a population reference and exchanged parameters, across population-training budgets.
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Signal Processing
Cross-Room Passive WiFi Tracking: Joint Estimation of Target Trajectory and Virtual Transmitter Location
Heping Wang, Zhongqin Wang, Henk Wymeersch et al. (+1 more)
Indoor bistatic WiFi sensing must often operate across rooms, where intervening walls block the direct line-of-sight (LOS) path between the transmitter (Tx) and receiver (Rx). Recovering a human trajectory from channel-state-information (CSI)-derived delay, angle-of-arrival (AoA), and Doppler estimates is difficult because the Tx position is often unknown and NLOS propagation is inconsistent with direct-path geometry. This paper presents CoTrack, a self-calibrating passive WiFi tracking scheme that does not require the Tx position. CoTrack extracts one dominant human-induced response and represents its transmitter-side propagation by a virtual Tx, which it estimates jointly with the human trajectory. Because similar measurements can be explained by different virtual-Tx–trajectory pairs, CoTrack uses multi-start nonlinear least squares and accepts an initialization only when the best-fitting candidates concentrate around a common virtual-Tx position. It then applies online alternating optimization for continuous tracking. We analyze the local identifiability of the joint estimation problem and derive the corresponding Cramér–Rao bound. Across six LOS and cross-room NLOS experiments, CoTrack achieves a median trajectory error of 1.14m(80th percentile: 1.42m) and a median virtual-Tx discrepancy of 0.47m(80th percentile: 0.54m).
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All authors Heping Wang, Zhongqin Wang, Henk Wymeersch, J. Andrew Zhang
Signal Processing
Movable Antenna-Enhanced MIMO-OFDM ISAC: Ambiguity Function Analysis, Waveform Design and Antenna Position Optimization
Tianqi Mao, Yuanshuo Gang, Guangyao Liu et al. (+3 more)
Multiple-input multiple-output orthogonal frequency division multiplexing (
MIMO-OFDM) provides abundant spatial and time-frequency degrees of freedom for integrated sensing and communication (
ISAC), while movable
antennas (MAs) further introduce reconfigurable spatial freedom through array geometry adjustment. However, how the array geometry and information bearing
MIMO-OFDM waveform jointly shape the three dimensional (3D) ambiguity response remains insufficiently understood, and conventional two dimensional (2D) range-Doppler metrics cannot fully characterize this coupling. This paper investigates MA-enhanced
MIMO-OFDM
ISAC with joint design of the transmit MA positions and symbol-level precoding (SLP) waveform. The discrete periodic angle-range-Doppler ambiguity function is first derived, and its structure is characterized in terms of waveform rank. It is proved that a rank one waveform yields a 3D ambiguity response that is separable between the angular dimension and the range-Doppler plane, whereas a higher rank waveform combines multiple spatial components with different weights across candidate angles, allowing the range-Doppler response to vary with the candidate angle and enabling the MA positions to further shape the 3D ambiguity response. Based on this analysis, a 3D integrated sidelobe level ratio (ISLR) is defined, the joint optimization of the MA positions and SLP waveform is formulated, and a penalty dual decomposition based alternating optimization
algorithm is developed. For the radar-only case, the existence of at least one rank one globally optimal solution is established, enabling a lossless reduction from the original high dimensional
MIMO-OFDM waveform design to a low dimensional joint design of the spatial beam and MA positions.
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All authors Tianqi Mao, Yuanshuo Gang, Guangyao Liu, Shiqi Cui, Ying Sun, Yifeng Xiong
Image and Video Processing
Gen2-VC: Unlocking Generative Priors for Video Compression
Yinhuan Huang, Jingkai Ying, Pu Chen et al. (+1 more)
Under stringent bitrate constraints, existing
video codecs struggle to balance source fidelity and perceptual realism. Distortion-oriented codecs often oversmooth details, while generative codecs risk introducing content and structural deviations and rely on codec-specific designs. This motivates a question: Can existing codecs achieve a better distortion–perception trade-off through simple, reusable adaptation? Our insight is that native codec reconstructions provide a shared interface through which generative refinement is anchored to source content while remaining decoupled from codec-specific representations. We therefore propose Gen2-VC, a generative
video compression framework that enhances the outputs of learned and conventional codecs with a pretrained
video prior, leaving their bitstreams and reference update processes unchanged. With the codec, VAE, and generative backbone frozen, lightweight LoRA adapters refine codec reconstruction through single-frame spatial adaptation followed by multi-frame temporal adaptation with the
video prior. Using Wan2.1-T2V-1.3B, Gen2-VC-DCVC-UF outperforms previous leading codecs in LPIPS/DISTS and, to our knowledge, is the first generative
video codec to surpass VTM-23.0 in both PSNR and MS-SSIM at low bitrates, based on BD-rates averaged over six
datasets. Compared to VTM-23.0, it reduces bitrate by an average of 86.65% and 94.24% at matched LPIPS and DISTS, respectively. Adapters trained only on DCVC-UF improve perceptual quality on DCVC-RT, ECM, VTM, and HM without retraining.
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All authors Yinhuan Huang, Jingkai Ying, Pu Chen, Zhijin Qin
Signal Processing
Intelligent Beamforming and Handover via Physics-Informed Beam-Aware CKM Diffusion
Le Zhao, Zesong Fei, Xinyi Wang et al. (+4 more)
Downlink communications from base stations (BSs) to unmanned aerial vehicles (
UAVs) in sixth-generation (6G) networks require precise beam
alignment to overcome severe mobile communication path loss. However, traditional exhaustive beam sweeping relies on discrete codebooks and consumes valuable air-interface resources for online measurements, rendering it inefficient for highly dynamic aerial environments. In this paper, we propose BeamCKMDiff, a physics-informed generative
diffusion framework designed to construct high-fidelity continuous beam-aware channel knowledge maps (BeamCKMs). Unlike existing empirical approaches, BeamCKMDiff employs a
diffusion transformer (DiT) architecture featuring a dual-path conditioning mechanism. It integrates an analytical line-of-sight (LoS) beam prior with environmental
topologies, while simultaneously
embedding continuous beamforming vectors through an adaptive layer normalization (adaLN) mechanism. Building upon this differentiable generative mapping, we propose a CKM-based end-to-end continuous beamforming and proactive dual-BS handover
algorithm. By analytically propagating gradients through the reverse
diffusion process, the proposed framework enables successive convex approximation (SCA)-based beamforming optimization in the computational domain, effectively bypassing physical pilot scanning. Simulation results demonstrate that BeamCKMDiff achieves a normalized mean square error (NMSE) of –23.96 dB, establishing a highly reliable spatial prior. Compared to discrete beam sweeping and LoS-assumed baselines, the proposed CKM-based beamforming adapts to non-LoS (NLoS) conditions, providing accurate beam
alignment and higher spectral efficiency. Furthermore, the integrated dual-BS handover mechanism eliminates blockage-induced link outages, ensuring robust connectivity for high-mobility aerial platforms.
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All authors Le Zhao, Zesong Fei, Xinyi Wang, Nan Ha, Yining Wang, Yong Zeng, Rui Zhang
Signal Processing
Hierarchical Clustering and Signal Denoising on Digraphs
Yi Wang, Sippanon Kitimoon, Hrushikesh N. Mhaskar et al. (+1 more)
In this paper, we propose a representation of a digraph (directed graph) as a Hermitian
matrix derived from its adjacency
matrix. This representation characterizes both the connectivity and the edge orientation of the digraph. Based on the spectral decomposition of the Hermitian
matrix, a digraph clustering
algorithm with $k$-means is introduced to produce a partition on the graph. Applying this
algorithm (bottom-up) recursively to a digraph with partially labeled vertices yields a spectral hierarchical digraph clustering (\myproj)
algorithm that produces consistent nested partitions of the digraph, or equivalently, a tree structure. Furthermore, based on the in-degree and out-degree of each cluster in the digraph clustering, a pair of hierarchical interval partitions (filtrations) can be derived in a top-down manner to produce a pair of nested
knot sequences. These
knot sequences facilitate the construction of multilevel spline quasi-interpolants, enabling a noisy graph signal to be decomposed into a coarse approximation and inter-level details, followed by adaptive thresholding and reconstruction. Experiments on synthetic and real-world digraphs demonstrate the superiority of our {\myproj}
algorithm for digraph clustering across diverse graph structural properties (homophily and heterophily) and supervision settings. Moreover, experiments on digraph signal processing using multilevel spline quasi-interpolants further demonstrate the effectiveness of signal recovery on digraphs in terms of RMSE and SNR.
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All authors Yi Wang, Sippanon Kitimoon, Hrushikesh N. Mhaskar, Xiaosheng Zhuang