Signal Processing
Distinguishing Process Change, Instrument Fault and Data-Path Corruption in Streaming Telemetry: A Reference Implementation and Benchmark
Oleksandr Klymenko
A reading departs from what a monitoring system expects for one of three reasons: the physical process changed, the instrument is failing, or the value was corrupted between the instrument and the software. The three call for different responses and look alike in a single sample. We state the three-cause problem, prove which pairs of causes one channel cannot separate, and propose a bank of online detectors - a Kalman tracker with CUSUM and EWMA charts on its innovation, a Hampel median with generalized-ESD confirmation, a robust noise statistic with ADWIN, exact-value checks and an optional two-channel complementary filter - combined by a deterministic, inspectable attribution rule. The detectors were merged into a public
algorithm library. On 2,942 injected events of thirteen fault types the method detects 96.3% (95% interval 95.7-97.0) at 0.22 false alarms per hour and attributes 91.2% (90.6-91.8) of detected events correctly from one channel and 99.0% (98.6-99.4) with a second, rate channel; from one channel only 2 of 207 detected sensor drifts are attributed to the instrument, as the problem statement predicts. Injected into recorded industrial signals, the same catalogue is detected at 80.8% and attributed correctly at 84.5%, at 3.6 false alarms per hour. On the Skoltech Anomaly
Benchmark the method detects 32 of 33 experiments with a median delay of 15 s, at 46 false alarms per hour against 11 for a rolling z-score.
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Signal Processing · Cross-listed from cs.CR
AutoSec-RAN: Specification-Grounded LLM Fine-Tuning for Automated Security Analysis of O-RAN
Anoop Mishra, Joshua Moore, Aly Sabri Abdalla et al. (+1 more)
This paper presents AutoSec-RAN, a specification-grounded large
language model (LLM) framework for automated security triage of Open
Radio Access Network (O-RAN) testing. Unlike approaches relying on static rule sets or privileged access to raw packet captures, AutoSec-RAN fine-tunes Mistral-7B-Instruct through two Low-Rank Adaptation (LoRA) stages over a curated corpus of 69 O-RAN, 3GPP, and adjacent standards documents, then selectively augments inference with
retrieval-augmented generation (RAG) over the same specification index. At inference, the model receives only an investigator-style question and a scenario metadata block, simulating an automated analyst operating without raw packet evidence. AutoSec-RAN is validated on a purpose-built 5G/O-RAN testbed across labeled fronthaul distributed denial of service replay scenarios. A Gemma-4-31B judge LLM scores each candidate's answer on faithfulness, correctness, and actionability relative to a reference authored from full packet capture and log evidence. AutoSec-RAN achieves a mean judge overall score of 0.713 across all 313 evaluation items (0.755 restricted to the five supervised taxonomy classes), clearing the 0.70 reporting threshold, and a blended score of 0.778 (0.808 supervised-only) when cosine similarity over Beijing Academy of Artificial Intelligence (BAAI) General
Embedding (BGE) is incorporated as a secondary semantic signal. The framework performs strongest on mitigation and threat-model
reasoning (with a mean overall of 0.849 and 0.848, respectively) and identifies a measurable gap on the held-out attack-direction class (0.515), a controlled result that exposes a specific training data requirement. These results establish specification-grounded LoRA fine-tuning combined with RAG
retrieval as a viable foundation for automated security validation of AI-native O-RAN.
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All authors Anoop Mishra, Joshua Moore, Aly Sabri Abdalla, Vuk Marojevic
Signal Processing
Completing Radio Map Tensors via Factor Diffusion Posterior Sampling
Le Xu, Rajesh Shrestha and Xiao Fu
Radio map estimation (RME), also known as spectrum cartography, aims to recover
radio signal strength across multiple domains (e.g., spatial and spectral domains) from sparse measurements, naturally leading to a tensor completion problem. Recent advances show that deep learning-based generative models can provide data-driven structural constraints for RME, yielding substantial performance improvements over traditional model-based approaches.
Diffusion models (DMs) represent the current state of the art in generative modeling and hold strong promise for advancing RME. However, existing
diffusion-based RME methods often require extensive training data, necessitate retraining when scenarios or measurement formats change, and lack recoverability guarantees. This paper proposes a latent factor
diffusion framework for spatio-spectral
radio map tensor completion. By training two independent DMs on single-emitter's spatial loss field and spectral signature and
embedding them into the factors of the
radio map tensor, the proposed approach enables
diffusion posterior sampling-based recovery with reduced training complexity as well as enhanced measurement format/sensing pattern flexibility. Recoverability and sample complexity guarantees under the proposed approach are also established. Numerical experiments validate the effectiveness of the proposed method, showing strong generalization across city environments unseen in training data.
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Audio and Speech Processing
Unsupervised Cross-device Speaker Diarization And Linking Through Spatiotemporal Structure
Suhas BN and Nikitha K
Linking speakers across independently recorded rooms is difficult because microphone, room, and codec mismatch distort speaker
embeddings. We study visitor linking without visitor enrollment or identity labels in simulated outpatient workflows. The proposed method combines per-device
embedding centering, concurrency constraints, room-type-specific visit constraints, and a clustering threshold calibrated from concurrent visitors and identified staff voices. On simulated days built from VOiCES recordings, with companions, return visits, walk-ins, silent visits, and acoustic leakage, it improves B$^3$-F1 over the best label-free baseline for all 11 extractors, by 5.3-14.6 points (all 95% intervals exclude zero). ECAPA-TDNN reaches 86.6, compared with 76.4 for the best label-free baseline and 87.7 for the best oracle-informed baseline. Gains persist across the reported workflow perturbations, but depend on removing duplicated cross-room
speech: without this step, the method wins for only 2 of 11 extractors. Single-visit patients also remain vulnerable to false merges. These results support structure-aware linking while identifying preprocessing and identity-safety limitations that must be addressed before clinical deployment.
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Audio and Speech Processing
Controllable Mono-to-Stereo Upmixing using Reward-tilted Flows
Sattwik Basu, Gautam Bhattacharya and Alan Seefeldt
We consider the problem of mono-to-stereo audio upmixing: generating a high-fidelity two-channel stereo signal from a single-channel recording. The task is fundamentally ill-posed i.e., many stereo signals are consistent with a given mono recording. An effective upmixer must therefore generate a realistic, musically coherent stereo image while preserving the underlying audio content. Previous approaches have relied on signal-processing driven decorrelation, ambience extraction and supervised learning, offering limited spatial control or requiring task-specific training. In response, we propose Aura (Audio Upmixing using Reward-tilted Flows), which reformulates upmixing as a generative inverse problem using a pretrained flow prior. To enable controllable spatial imaging, we design a reward-tilted posterior sampler whose reward penalizes divergences between generated and target distributions of inter-channel cues. Composing forward operators further enables joint restoration and upmixing without retraining or fine-tuning. Objective and subjective evaluations on real-world music recordings from MUSDB18-HQ demonstrate our method's effectiveness relative to several baselines.
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Systems and Control
Distributed Observation Scheduling and Sensor Fusion For Large Agile Constellations
Nicholas Niziolek, Ryan Draves, Nolan Ales et al. (+4 more)
With the rapid increase in interest towards large scale earth observing satellite constellations, the problem of properly commanding and utilizing these systems has become increasingly relevant. This work focuses on a complete distributed approach to this problem, incorporating an observation task allocation and scheduling
algorithm in addition to a sensor data fusion
algorithm for end-to-end target coverage and processing. Observation task allocation and scheduling is performed in this work through the combination of the bid warped consensus based bundle
algorithm (BWCBBA) and a lightweight observation scheduler for bid scoring. This method produces a unique mapping of tasks to command
agents when allowed to iterate sufficiently. The approach to distributed data fusion in this work occurs primarily through an ownership model in which one satellite takes ownership of a system track in the constellation. After local information is shared between the sensing nodes to create the system tracks, the dedicated fusion nodes assume ownership for further information fusion and track information is disseminated throughout the constellation for data association. This paper analyzes the performance of these two
algorithms over a set of increasingly decentralized architectures to highlight the performance losses compared to more traditional centralized methods.
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All authors Nicholas Niziolek, Ryan Draves, Nolan Ales, Nolan Stevenson, Eli Jones, Eric Frew, Nisar Ahmed
Systems and Control
Physics-guided machine learning for saturation control across variable hydraulic conditions in heap leaching
Sultan Alhamdan, Daniel Navia and Paulina Quintanilla
Heap-leaching hydraulics vary between regions of an ore bed, motivating fast prediction models that accommodate different material properties. This study develops a parameter-conditioned physics-guided machine-learning (PGML) surrogate and demonstrates its use in simulated saturation control. A
dataset of 4096 numerical Richards-equation trajectories was divided into 2867 training, 614 validation and 615 evaluation cases. The network predicts hourly saturation profiles from the current profile, irrigation rate and four hydraulic parameters, and is trained with an approximate Gardner mass-balance penalty. A daily predictive controller compared 200 constant irrigation rates over a 24-hour horizon. Across the evaluation cases, the median full-cycle tracking deviation was 4.9% of a 0.70 saturation target, equal to that of a tuned proportional-integral (PI) controller, while the PGML controller reached the target without overshoot in the median and applied approximately 4% less irrigation. Moderate physics guidance reduced long-horizon prediction error by approximately 30% relative to data-only training and reduced irrigation-bound activity, but slightly worsened closed-loop tracking. For a matched prediction workload, the surrogate was approximately 70 times faster than the numerical solver, and batched evaluation cost under 2 ms per column for 5000 columns. The results support a reusable physics-guided surrogate for large-scale saturation control in simulation.
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Systems and Control
Rayleigh-Benard Stabilization by Fredholm Backstepping
Miroslav Krstic and Eugene Lavretsky
Among Navier–Stokes systems, the Rayleigh–Bénard layer, a fluid between two horizontal plates heated from below and cooled from above, is the
benchmark of hydrodynamic instability that manifests itself as the unsteady convection phenomenon, which in turn can be interpreted as the onset of chaos: the Lorenz equations represent the
Fourier–Galerkin approximation coefficients for the minimal three-mode truncation of it. Its instability has no mean flow behind it. The fluid is at rest, the velocity and the temperature are each stable alone, and buoyancy closes a positive loop between them. The linearization is self-adjoint, its unstable spectrum real, and the number of unstable modes grows without bound in the Rayleigh number; at $\Ra=10^6$ the layer has $85$ of them, with growth rates up to $2137$. We stabilize the conductive state at every Rayleigh and Prandtl number, with any prescribed decay rate, by explicit feedback of the full state to the tangential velocity, temperature, and normal velocity of the upper plate. The feedback laws are obtained by Fredholm backstepping of the coupled velocity–temperature system, with pole placement for the lowest modes.
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Systems and Control · Cross-listed from cs.RO
Jacobian State Augmented Viable Kinematic Safety Filter
Siddharth Singh and Joshua Vaughan
Safety Filters (SF) are leveraged to design certifiably safe controllers, which ensures forward invariance on a defined safe set when the filter is feasible. Predictive Safety Filters (PSF) embed these constraints to a closed-loop model-based optimization method to improve constraint satisfaction, and reduce feasibility loss caused by myopic, one-step filtering. Related viability-based methods emphasize approximating a viability kernel which ensures admissible control for all future time, but requires significant computational expense. This work introduces a Jacobian-based kinematic safety filter leveraging an augmented state variable with task-space velocity and filters task-space acceleration to preserve the feasibility of a low-level filter while enforcing joint position and velocity. The proposed method introduces a nested Quadratic Program (QP) formulation, defines a conservative inner approximation of viability envelope and computes a viable planner online. The method is validated in a simplified 2R planar manipulator simulation environment and shows significant improvement compared to a baseline Control Barrier Function Quadratic Program (CBF-QP) based filter. The experiments highlights the improvements in terms of computation time compared to traditional PSF and Reference Governor approach while also showing significant reduction in feasibility violations. Lastly, a simplified demonstration on a simulated 6-DoF manipulator highlights the potential scalability of the method to higher degree-of-freedom setups.
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Systems and Control · Cross-listed from cs.RO
Efficient Hybrid Hard–Soft Signal Temporal Logic MPC for Driving under Multimodal Uncertainty
Kumar Manas and Adrian Paschke
Motion planning for automated vehicles in interactive traffic has to simultaneously ensure safety, respect traffic rules, and maintain comfortable progress under multi-modal behavior uncertainty. Imposing all these requirements as hard constraints reduces feasibility, whereas treating them all as costs allows safety-critical requirements to be traded against progress. We propose a hybrid hard–soft Signal Temporal Logic (STL) MPC framework that optimizes a single shared ego trajectory against every retained behavior hypothesis: minimum-distance and speed predicates are imposed as explicit hard constraints, while soft STL robustness terms shape clearance, comfort, and interaction quality within the resulting feasible driving corridor. This retains robustness to discrete interaction modes without branch-specific contingent ego policies. We further identify substantial symbolic graph-construction overhead and introduce reachability-certified relevance screening and vectorized symbolic construction to reduce computational cost while preserving the feasible set and objective. Closed-loop Monte Carlo evaluation over six highway and intersection scenarios shows the highest strict success rate among the compared planners with no observed collisions or rule violations, at roughly a quarter of the planning latency of the unoptimized formulation. An ablation study separates the two layers: the hard constraints define the safety envelope, while the soft terms improve clearance and motion quality within it.
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Systems and Control
Singular Sampling in Nonlinear Observability: Higher-Order Minimax Laws and Timing Crossovers
Jerzy Baranowski
We study deterministic bounded-noise state reconstruction for nonlinear systems when the measurement schedule drives the sampled-output map through a rank-deficient configuration. Local reconstruction is governed by the leading pairwise separation order and its corresponding higher-order modulus, which together determine the leading minimax noise-to-state law. For corank-one cubic singular schedules, including overdetermined sampled maps, we derive the exact physical $\ell_\infty$ cubic modulus through quotient geometry in $\mathbb{R}^q/\operatorname{Im}DF$ and show how the required finite jet is computed from trajectory sensitivities. We then prove a uniform signed timing crossover: a transversal timing perturbation has transition scale $\varepsilon=O(\delta^{2/3})$, linking the regular, cubic-singular, and fold regimes. A damped pendulum provides closed-form crossover coefficients and exact nonlinear minimax validation, while a four-state downward cart–pole verifies the rectangular theory. The results show that measurement timing can change not only reconstruction conditioning but the exponent governing bounded-noise state uncertainty.
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Signal Processing
The Role of Generative Artificial Intelligence in Testing and Automation of Open RAN Systems: GNG-OTA Framework
Aly Sabri Abdalla and Vuk Marojevic
Open
Radio Access Networks (O-RAN) empower operators with choice and customization through their disaggregated and interoperable architecture. However, ensuring interoperability in O-RAN presents challenges due to complex testing environments and evolving specifications. This paper addresses these challenges by proposing the Generative AI and Graph Neural Network-based Open RAN Testing and Automation (GNG-OTA) framework. GNG-OTA utilizes state-of-the-art AI techniques including generative AI, natural
language processing, and graph neural networks to enable accurate, reliable, efficient, and automatic O-RAN interoperability and performance testing.
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Image and Video Processing · Cross-listed from stat.CO
Jensen-Bregman split Gibbs sampling
Nicolas Dobigeon, Mame Diarra Fall and Eric Barat
Split Gibbs sampling (SGS) is a versatile tool to sample from complex posterior distributions, such as those arising in imaging inverse problems. However, existing SGS instances are limited to quadratic variable couplings, restricting their applicability to Gaussian likelihoods. This letter genearalizes SGS to non-Euclidean geometry by introducing a coupling kernel defined through a Jensen-Bregman divergence. This framework not only enables posterior sampling in these settings but also unifies several ad hoc sampling schemes from the literature under a principled theoretical foundation.
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Audio and Speech Processing
High-Fidelity Song Generation with Joint Discrete and Continuous Modeling
Zheqi Dai, Zhiyue Wu, Ruibin Yuan et al. (+5 more)
Generating a full song from lyrics and a style description requires long-range musical planning without sacrificing vocal and instrumental detail. Low-rate discrete semantic
tokens make this tractable, but quantization constrains the information available to acoustic rendering, while separately optimized stages prevent downstream generation objectives from shaping the planner. We propose joint discrete and continuous modeling for high-fidelity song generation. A VQ tokenizer supplies
tokens for autoregressive planning, and a separately trained SSL-derived variational encoder supplies continuous semantic targets. Conditioned on the completed
token plan and differentiable readouts of the planner's predictive states, a full-sequence flow model generates semantic features for acoustic rendering. Its flow-matching gradients reach the
language model through the readouts, without differentiating through
token sampling; the standard pathway keeps continuous features out of autoregressive feedback. On 192 shared
prompts, its 48D configuration improves SongEval from 4.152 to 4.269 and reduces micro-PER from 20.26% to 14.47% relative to a discrete baseline, while receiving substantially higher expert listening scores. We further analyze the system through downstream semantic probes and conditioned reconstruction.
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All authors Zheqi Dai, Zhiyue Wu, Ruibin Yuan, Haolin He, Chunyat Wu, Xuerui Yang, Qiuqiang Kong, Chao Yan
Systems and Control · Cross-listed from quant-ph
Quantum ordinal optimization under a fixed comparison budget
Hongyu Wu
Ordinal optimization selects designs that are good enough rather than optimal when evaluation is expensive and the budget is small. The
alignment probability measures the chance that the selected set contains at least a prescribed number of truly good designs. We formulate
quantum ordinal optimization as a class of problems that maximize this probability under a fixed oracle budget. We study exact, coherent pairwise comparisons with one selected design as a first instance, with the budget counted in comparison queries. For every classical comparison budget smaller than the number of designs, we prove that a knockout among uniformly sampled designs attains the optimum. The sample is drawn without replacement and contains one more design than the number of comparisons. For a uniformly random order, the selected design's rank has a
polynomial probability law. At the same comparison budget, the maximum
quantum degree is at most twice the classical maximum, a factor attained whenever there are more than twice as many designs as comparisons, so a
quantum algorithm can realize rank laws that no classical
algorithm with the same budget can. We determine the exact
quantum optimum with one comparison for every number of designs and every good-enough set. For selecting the best of n designs, the optimal success probability with one
quantum comparison is approximately 3.30/n for large n, compared with 2/n for one classical comparison. When the best design is sought, one
quantum comparison gives a higher
alignment probability than two classical comparisons whenever there are more than nine designs.
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Audio and Speech Processing
HMU-Bench: Hierarchical Music Understanding Benchmark for Omni Models
Zheqi Dai, Boyang Wang, Zhiyue Wu et al. (+6 more)
Music-understanding
benchmarks should identify both the evidence available to a model and the operations a correct answer requires. We introduce HMU-Bench, a bilingual
benchmark with notation and audio components. ABC Q&A contains 1,029 Chinese-English question pairs across six musical domains, labeled as extraction, single-step inference, or multi-step inference. Audio Q&A contains 460 question pairs on 92 recordings, spanning five scope-difficulty configurations. All music is Suno-generated, and questions and references are human-reviewed. Reference-based evaluation of seven omni models yields high notation scores for the strongest systems, but no model averages above 1.4 on the 0-4 audio scale. Notation and audio rankings show little correlation. A transposition case study also reveals octave errors missed by LLM grading. These findings motivate separate modality reporting and event-level checks for symbolic outputs. Data, annotations, evaluator
prompts, and graded responses will be released at https://github.com/stepaudiollm/hmu-bench.
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All authors Zheqi Dai, Boyang Wang, Zhiyue Wu, Yiyang Xu, Xinming Shi, Ruibin Yuan, Xuerui Yang, Chao Yan, Qiuqiang Kong
Systems and Control · Cross-listed from cs.RO
Model-Based Trailer-Sway Suppression for Autonomous Passenger Vehicles
Alec McFadyen, Pablo Covarrubias De La Torre and Connor McGovern
Trailer sway is a persistent contributor to severe crashes among light passenger vehicles towing trailers, yet it remains largely unaddressed by the autonomous vehicle systems now entering this new era of automation. Improper cargo placement rearward of the trailer axle reduces, and can invert, the tongue load transmitted through the hitch. The resulting loss of vertical load at the tow vehicle's rear axle diminishes the lateral tire force available there and degrades yaw stability of the coupled system, admitting a divergent lateral oscillation of the trailer known as trailer sway. Under adverse combinations of speed and loading, this oscillation can progress to jackknifing, in which the articulation angle diverges rapidly and directional control is lost. This work develops a linear state-space model of the yaw-plane dynamics of a light vehicle-trailer combination, parameterized to expose tongue load as an explicit stability-determining quantity. From this model a linear quadratic regulator is synthesized to suppress articulation-angle divergence. Because consumer trailers carry no sensors, the two trailer states the controller needs, trailer yaw rate and articulation angle, are estimated by a Kalman filter from measurements taken only on the tow vehicle. The controller is then implemented and evaluated in a MuJoCo multibody simulation across a range of longitudinal speeds and tongue-load conditions, including the negative-tongue-load regime. Results show a significant decrease in trailer oscillation when controlling a given vehicle's steering with an LQR using tow-vehicle IMU and
LiDAR data. These findings indicate that LQR controlled anti-sway systems are a viable control method for future autonomous vehicles.
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Signal Processing
Theoretical Investigation of Nonclassical Directional Emission in 1D and 2D Quantum-Dot Antenna Arrays and Quantum DoA Estimation
Angeru Pavan Kumar and Sandip Ghosal
A
quantum-dot array prepared in a timed Dicke state exhibits directional radiation asymmetry, which has often been interpreted as evidence of reciprocity breaking through
quantum-state preparation. We show that this interpretation is incorrect: reciprocity concerns transmit-receive response, not necessarily pattern
symmetry. Moreover, the first-order coherence of any single-excitation state is exactly equivalent to the power pattern of a classical phased array driven by conjugate weights, making the observed asymmetry classically reproducible. The genuine
quantum signature instead appears in second-order correlations, where a single-excitation state violates the classical lower bound on
photon coincidences. We therefore propose a
quantum-
antenna certificate combining nonzero directional asymmetry with
photon antibunching at the beam peak. We further derive a tight asymmetry bound, establish the correct mirror operation for planar arrays, correct the collective decay rate with dipole-dipole coupling, and derive a saturation law for direction-finding precision. All theoretical results are validated through independent numerical implementations.
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Systems and Control
Learned Graph Bases for Neural Operators on Power-System Transients
Shubhan Bhattacharya and Avi Bagchi
Fourier neural operators predict power-system transient trajectories with high accuracy. We extend this line of work by examining the choice of spatial spectral basis, studying both the graph
Fourier transform derived from the grid's own coupling network and learnable bases trained from that starting point and from a
Fourier control. Evaluated in one controlled pipeline across three protocols spanning unseen fault locations and shifted operating regimes, the learnable bases improve on a parameter- and budget-matched DFT variant by 7-14% in distribution, with per-case significance on both in-distribution protocols and no loss on the third; the gain comes from adaptation rather than from the coordinates alone. We further characterize the regime dependence of this gain, identifying its cause, locus, and continuity, and show that a resolution requires no new model: averaging the learned and frozen variants gives the best shift-robust predictor, while their disagreement provides a label-free alarm that flags every shifted case with no false alarms.
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Systems and Control
Distributed Economic Dispatch Scheme of A BESS Network with A Switching Utility Grid in Energy Internet Paradigm via Reset Consensus Method
Yalin Zhang, Zhongxin Liu, Yulin Chen et al. (+2 more)
This article aims to design a distributed economic dispatch (ED) scheme based on marginal cost (MC) consensus for a battery energy storage system (BESS) network considering the utility grid switching. Due to the low control accuracy and slow convergence speed of previous schemes, some important changes have been made in this article. Firstly, the feedback coupling term is introduced into the closed-loop error to further improve the stability and convergence rate of the controller. Then, a proportional integral (PI) controller with a reset mechanism is implemented in the designed scheme, which improves the speed and control accuracy of MC consensus. The performance of a control system with a reset mechanism is well guaranteed by analyzing the
eigenvalues of the corresponding
matrix. Finally, some tests focus on UG switching, time phased pricing, load switching, a BESS/
agent plug and play, and large-scale system applications to illustrate the effectiveness and progressiveness of the design scheme.
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All authors Yalin Zhang, Zhongxin Liu, Yulin Chen, Donglian Qi, Zengqiang Chen
Signal Processing
Bistatic Delay-Doppler Sensing for 3D Target Localization in Distributed Wi-Fi Systems
Kyungmin Hong, Moein Ahmadi, Thomas Stifter et al. (+2 more)
This paper investigates how bistatic delay information improves the observability and localization performance of 3D moving targets in distributed Wi-Fi sensing. Motivated by emerging IEEE 802.11bf WLAN sensing, we consider one transmitter, multiple distributed receivers, and a single target with unknown position and velocity. We compare Doppler-only sensing with delay-Doppler sensing, in which delay-capable receivers provide additional bistatic path-length information for target localization. We derive the Fisher information
matrix (FIM) and the position equivalent FIM (EFIM) for both sensing formulations. The resulting observability analysis shows that Doppler-only localization generically requires six receivers, whereas delay-Doppler localization can become locally identifiable with three receivers under non-degenerate geometry. We further study mixed receiver architectures in which only a subset of receivers provides delay estimates. Simulations with Wi-Fi-like bandwidths confirm the transition and quantify the roles of bandwidth, Doppler noise, receiver geometry, and delay-capable receiver availability.
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All authors Kyungmin Hong, Moein Ahmadi, Thomas Stifter, Mounim A. El Yacoubi, Bhavani Shankar Mysore R
Signal Processing
Physical Layer Security for Movable Antenna-Aided Mixed-Field ISAC
Yun Xiao, Enhao Wang, Yunfei Chen et al. (+3 more)
Movable
antenna (MA) can enhance the physical layer security (PLS) performance of integrated sensing and communications (
ISAC). However, most existing works assume either near-field (NF) or far-field (FF) propagation models for both communication users (CUs) and targets. This paper considers a more practical scenario where multiple CUs, an eavesdropper (Eve), and multiple targets are in a mixed near- and far-field environment due to the changes in the propagation field caused by
antenna position updates in MA with a unified array response and continuous NF/FF weights. To evaluate the PLS performance of MA-aided
ISAC in mixed-field environments, we formulate an optimization problem to maximize the sum secrecy rate (SSR) of CUs by jointly designing the transmit beamforming and
antenna positions at the transmitter. The problem is highly non-convex, so a two-layer
algorithm is proposed to iteratively solve the problem using the projected gradient ascent (PGA) method and the Lagrangian dual transform. Since the abrupt switch between the NF and the FF models during
antenna movement can cause the objective function to oscillate during iteration, the unified array response is combined with the Barzilai-Borwein step, Armijo line search, and precise projection to ensure that the SSR does not decrease during the iteration and the objective function is differentiable on the Rayleigh boundary. Numerical results show that the MA-
ISAC using the mixed-field model achieves almost identical PLS performance to that of using the full NF model in terms of SSR, and both outperform the FF model. Using the mismatched FF model during
antenna position updates results in a loss of MA gain, potentially making MA inferior to the FA-based system using the correct model.
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All authors Yun Xiao, Enhao Wang, Yunfei Chen, Aissa Ikhlef, Zhuangkun Wei, Hongjian Sun