Image and Video Processing · Cross-listed from cs.CV
XD-MAP: Cross-Modal Domain Adaptation via Semantic Parametric Maps for Scalable Training Data Generation
Frank Bieder, Hendrik Königshof, Haohao Hu et al. (+4 more)
Until open-world foundation models match the performance of specialized approaches, deep learning systems remain dependent on task- and sensor-specific data availability. To bridge the gap between available
datasets and deployment domains, domain adaptation strategies are widely used. In this work, we propose XD-MAP, a novel approach to transfer sensor-specific knowledge from an image
dataset to
LiDAR, an entirely different sensing domain. Our method leverages detections on camera images to create a semantic parametric map. The map elements are modeled to produce pseudo labels in the target domain without any manual annotation effort. Unlike previous domain transfer approaches, our method does not require direct overlap between sensors and enables extending the angular perception range from a front-view camera to a full 360{\deg} view. On our large-scale road feature
dataset, XD-MAP outperforms single shot baseline approaches by +19.5 mIoU for 2D semantic
segmentation, +19.5 PQth for 2D panoptic
segmentation, and +32.3 mIoU in 3D semantic
segmentation. The results demonstrate the effectiveness of our approach achieving strong performance on
LiDAR data without any manual labeling.
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All authors Frank Bieder, Hendrik Königshof, Haohao Hu, Fabian Immel, Yinzhe Shen, Jan-Hendrik Pauls, Christoph Stiller
Systems and Control
All-Pass Fractional OPF: A Solver-Friendly, Physics-Preserving Approximation of AC OPF
Milad Hasanzadeh, Amin Kargarian and Javad Lavaei
This paper presents a fractional approximation of the AC optimal power flow (AC OPF) problem based on an all-pass approximation of the exponential power flow kernel. The classical AC OPF relies on trigonometric coupling between bus voltage phasors, which yields a nonconvex program with oscillatory derivatives that can slow, or in some cases destabilize, interior-point methods. We replace the trigonometric terms with an all-pass fractional (APF) approximation whose real and imaginary components act as smooth surrogates for the cosine and sine functions, and we introduce a pre-rotation to shift the argument of the approximation toward its most accurate region, ensuring that the reformulated power flow model preserves physical loss behavior, maintains the
symmetry of the classical kernels, and improves the conditioning of the Jacobian and Hessian
matrices. The proposed APF OPF formulation remains nonconvex, as in the classical model, but it eliminates trigonometric evaluations and empirically produces larger and more stable Newton steps under standard interior-point solvers. Numerical results on more than 25 IEEE and PGLib test systems ranging from 9 to 10{,}000 buses demonstrate that the APF OPF model achieves solutions with accuracy comparable to that of the classical formulation while reducing solver times, indicating a more solver-friendly nonconvex representation of AC OPF. All code, functions, verification scripts, and generated results are publicly available on \href{https://github.com/LSU-RAISE-LAB/APF-OPF}{GitHub}, along with a README describing how to run and reproduce the experiments.
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Systems and Control · Cross-listed from math.OC
Event-Triggered Newton Extremum Seeking for Multivariable Optimization
Victor Hugo Pereira Rodrigues, Tiago Roux Oliveira, Miroslav Krstic et al. (+1 more)
This paper presents a static event-triggered control strategy for multivariable Newton-based extremum seeking. The proposed method integrates event-triggered actuation into the Newton-based optimization framework to reduce control updates while maintaining rapid convergence to the extremum. Unlike traditional gradient-based extremum seeking, where the convergence rate depends on the unknown Hessian of the cost function, the proposed approach employs a dynamic
estimator of the Hessian inverse, formulated as a Riccati equation, enabling user-assignable convergence rates. The event-triggering mechanism is designed to minimize unnecessary actuation updates while preserving stability and performance. Using averaging theory, we establish local stability results and exponential convergence to a neighborhood of the unknown extremum point. Additionally, numerical simulations illustrate the benefits of the proposed approach over gradient-based and continuously actuated Newton-based extremum seeking, showing improved convergence rates and reduced control update frequency, leading to more efficient implementation in real-time optimization scenarios.
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All authors Victor Hugo Pereira Rodrigues, Tiago Roux Oliveira, Miroslav Krstic, Paulo Tabuada
Systems and Control · Cross-listed from math.OC
$\pi$MPC: A Parallel-in-horizon and Construction-free NMPC Solver
Liang Wu, Bo Yang, Junheng Li et al. (+5 more)
The alternating direction method of multipliers (ADMM) has gained increasing popularity in embedded model predictive control (MPC) due to its code simplicity and pain-free parameter selection. However, existing ADMM solvers either target general quadratic programming (QP) problems or exploit sparse MPC formulations via Riccati recursions, which are inherently sequential and therefore difficult to parallelize for long prediction horizons. This technical note proposes a novel parallel-in-horizon and construction-free nonlinear MPC
algorithm, termed $\pi$MPC, which combines a new variable-splitting scheme with a velocity-based system representation in the ADMM framework, enabling horizon-wise parallel execution while operating directly on system
matrices without explicit MPC-to-QP construction. Numerical experiments and accompanying code are provided to validate the effectiveness of the proposed method.
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All authors Liang Wu, Bo Yang, Junheng Li, Xu Yang, Yilin Mo, Yang Shi, Aaron D. Ames, Ján Drgoňa
Image and Video Processing · Cross-listed from cs.CV
Large-Scale Label Quality Assessment for Medical Segmentation via a Vision-Language Judge and Synthetic Data
Yixiong Chen, Zongwei Zhou, Wenxuan Li et al. (+1 more)
Large-scale medical
segmentation datasets often combine manual and pseudo-labels of uneven quality, which can compromise training and evaluation. Low-quality labels may hamper performance and make the model training less robust. To address this issue, we propose SegAE (
Segmentation Assessment Engine), a lightweight
vision-
language model (VLM) that automatically predicts label quality across 142 anatomical structures. Trained on over four million image-label pairs with quality scores, SegAE achieves a high correlation coefficient of 0.902 with ground-truth Dice similarity and evaluates a 3D mask in 0.06s. SegAE shows several practical benefits: (I) Our analysis reveals widespread low-quality labeling across public
datasets; (II) SegAE improves data efficiency and training performance in active and semi-supervised learning, reducing
dataset annotation cost by one-third and quality-checking time by 70% per label. This tool provides a simple and effective solution for quality control in large-scale medical
segmentation datasets. The
dataset, model weights, and codes are released at https://github.com/Schuture/SegAE.
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All authors Yixiong Chen, Zongwei Zhou, Wenxuan Li, Alan Yuille
Systems and Control · Cross-listed from cs.CR
Rethinking On-Device LLM Reasoning: Why Analogical Mapping Outperforms Abstract Thinking for IoT DDoS Detection
William Pan, Guiran Liu, Binrong Zhu et al. (+4 more)
The rapid expansion of IoT deployments has intensified cybersecurity threats, notably Distributed Denial of Service (DDoS) attacks, characterized by increasingly sophisticated patterns. Leveraging Generative AI through On-Device Large
Language Models (ODLLMs) provides a viable solution for real-time threat detection at the network edge, though limited computational resources present challenges for smaller ODLLMs. This paper introduces a novel detection framework that integrates Chain-of-Thought (CoT)
reasoning with
Retrieval-Augmented Generation (RAG), tailored specifically for IoT edge environments. We systematically evaluate compact ODLLMs, including LLaMA 3.2 (1B, 3B) and Gemma 3 (1B, 4B), using structured prompting and exemplar-driven
reasoning strategies. Experimental results demonstrate substantial performance improvements with few-shot prompting, achieving macro-average F1 scores as high as 0.85. Our findings highlight the significant advantages of incorporating exemplar-based
reasoning, underscoring that CoT and RAG approaches markedly enhance small ODLLMs' capabilities in accurately classifying complex network attacks under stringent resource constraints.
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All authors William Pan, Guiran Liu, Binrong Zhu, Qun Wang, Yingzhou Lu, Beiyu Lin, Rose Qingyang Hu
Systems and Control · Cross-listed from physics.optics
VCSEL-based CPO for Scale-Up in A.I. Datacenter. Status and Perspectives
Manuel Kohli and Jean Teissier
The drastic increase of bandwidth demands in AI datacenters requires new solutions with low power consumption and high bandwidth densities. Further increasing the total bandwidth with copper interconnects is challenging, thus it is crucial to introduce optics into the scale-up network. For this purpose, the most important metrics are the energy efficiency of the total link in addition to the spatial bandwidth-density and reach. With the inefficiency of copper traces at high speeds, transitioning to co-packaged optics is no longer optional but essential. Here, we show that the mature VCSEL technology offers the ideal combination of low-cost, low-latency, high-reliability, and energy efficiency at all bitrates, thanks to their unique versatility and high wall-plug-efficiency. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.
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Image and Video Processing
Partial Decoder Attention Network with Contour-weighted Loss Function for Data-Imbalance Medical Image Segmentation
Zhengyong Huang, Ning Jiang, Xingwen Sun et al. (+4 more)
Image
segmentation is pivotal in medical image analysis, facilitating clinical diagnosis, treatment planning, and disease evaluation. Deep learning has significantly advanced automatic
segmentation methodologies by providing superior modeling capability for complex structures and fine-grained anatomical regions. However, medical images often suffer from data imbalance issues, such as large volume disparities among organs or tissues, and uneven sample distributions across different anatomical structures. This imbalance tends to bias the model toward larger organs or more frequently represented structures, while overlooking smaller or less represented structures, thereby affecting the
segmentation accuracy and robustness. To address these challenges, we proposed a novel contour-weighted
segmentation approach, which improves the model's capability to represent small and underrepresented structures. We developed PDANet, a lightweight and efficient
segmentation network based on a partial decoder mechanism. We evaluated our method using three prominent public
datasets. The experimental results show that our methodology excelled in three distinct tasks: segmenting multiple abdominal organs,
brain tumors, and pelvic bone fragments with injuries. It consistently outperformed nine state-of-the-art methods. Moreover, the proposed contour-weighted strategy improved
segmentation for other comparison methods across the three
datasets, yielding average enhancements in Dice scores of 2.32%, 1.67%, and 3.60%, respectively. These results demonstrate that our contour-weighted
segmentation method surpassed current leading approaches in both accuracy and robustness. As a model-independent strategy, it can seamlessly fit various
segmentation frameworks, enhancing their performance. This flexibility highlighted its practical importance and potential for broad use in medical image analysis.
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All authors Zhengyong Huang, Ning Jiang, Xingwen Sun, Lihua Zhang, Peng Chen, Jens Domke, Yao Sui
Image and Video Processing
Unsupervised Deformable Image Registration with Local-Global Attention and Image Decomposition
Zhengyong Huang, Xingwen Sun, Xuting Chang et al. (+5 more)
Deformable image registration is a critical technology in medical image analysis, with broad applications in clinical practice such as disease diagnosis, multi-modal fusion, and
surgical navigation. Traditional methods often rely on iterative optimization, which is computationally intensive and lacks generalizability. Recent advances in deep learning have introduced
attention-based mechanisms that improve feature
alignment, yet accurately registering regions with high anatomical variability remains challenging. In this study, we proposed a novel unsupervised deformable image registration framework, LGANet++, which employs a novel local-global
attention mechanism integrated with a unique technique for feature interaction and fusion to enhance registration accuracy, robustness, and generalizability. We evaluated our approach using five publicly available
datasets, representing three distinct registration scenarios: cross-patient, cross-time, and cross-modal CT-MR registration. The results demonstrated that our approach consistently outperforms several state-of-the-art registration methods, improving registration accuracy by 1.39% in cross-patient registration, 0.71% in cross-time registration, and 6.12% in cross-modal CT-MR registration tasks. These results underscore the potential of LGANet++ to support clinical workflows requiring reliable and efficient image registration. The source code is available at https://github.com/huangzyong/LGANet-Registration.
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All authors Zhengyong Huang, Xingwen Sun, Xuting Chang, Ning Jiang, Yao Wang, Jianfei Sun, Hongbin Han, Yao Sui
Image and Video Processing
Self-Supervised Score-Based Despeckling for SAR Imagery via Log-Domain Transformation
Junhyuk Heo
The speckle noise inherent in Synthetic Aperture Radar (SAR) imagery significantly degrades image quality and complicates subsequent analysis. Given that SAR speckle is multiplicative and Gamma-distributed, effectively despeckling SAR imagery remains challenging. This paper introduces a novel self-supervised framework for SAR image despeckling based on score-based generative models operating in the transformed log domain. We first transform the data into the log-domain and then convert the speckle noise residuals into an approximately additive Gaussian distribution. This step enables the application of score-based models, which are trained in the transformed domain using a self-supervised objective. This objective allows our model to learn the clean underlying signal by training on further corrupted versions of the input data itself. Consequently, our method exhibits significantly shorter inference times compared to many existing self-supervised techniques, offering a robust and practical solution for SAR image restoration.
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Signal Processing
Robust Localization in OFDM-Based Massive MIMO through Phase Offset Calibration
Qing Zhang, Adham Sakhnini, Robbert Beerten et al. (+4 more)
Accurate localization in Orthogonal Frequency Division Multiplexing (OFDM)-based massive Multiple-Input Multiple-Output (
MIMO) systems depends critically on phase coherence across subcarriers and
antennas. However, practical systems suffer from frequency-dependent and (spatial)
antenna-dependent phase offsets, degrading localization accuracy. This paper analytically studies the impact of phase incoherence on localization performance under a static User Equipment (UE) and Line-of-Sight (LoS) scenario. We use two complementary tools. First, we derive the Cramér-Rao Lower Bound (CRLB) to quantify the theoretical limits under phase offsets. Then, we develop a Spatial Ambiguity Function (SAF)-based model to characterize ambiguity patterns. Simulation results reveal that spatial phase offsets severely degrade localization performance, while frequency phase offsets have a minor effect in the considered system configuration. To address this, we propose a robust Channel State Information (CSI) calibration framework and validate it using real-world measurements from a practical massive
MIMO testbed. The experimental results confirm that the proposed calibration framework significantly improves the localization Root Mean Squared Error (RMSE) from 5 m to 1.2 cm, aligning well with the theoretical predictions.
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All authors Qing Zhang, Adham Sakhnini, Robbert Beerten, Haoqiu Xiong, Zhuangzhuang Cui, Yang Miao, Sofie Pollin
Image and Video Processing
LRC-DHVC: Towards Local Rate Control in Neural Video Compression
Marc Windsheimer, Simon Deniffel and André Kaup
Local rate control is a key enabler to generalize image and
video compression for dedicated challenges, such as
video coding for machines. While traditional hybrid
video coding can easily adapt the local rate-distortion trade-off by changing the local quantization parameter, no such approach is currently available for learning-based
video compression. In this paper, we propose LRC-DHVC, a hierarchical
video compression network, which allows continuous local rate control on a pixel level to vary the spatial quality distribution within individual
video frames. This is achieved by concatenating a quality map to the input frame and applying a weighted MSE loss which matches the pixelwise trade-off factors in the quality map. During training, the model sees a variety of quality maps due to a constrained-random generation. Our model is the first neural
video compression network, which can continuously and spatially adapt to varying quality constraints. Due to the wide quality and bit rate range, a single set of network parameters is sufficient. Compared to single rate point networks, which scale linearly with the number of rate points, the
memory requirements for our network parameters remain constant. The code and model are available at link-updated-upon-acceptance.
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Signal Processing
Burst Aware Forecasting of User Traffic Demand in LEO Satellite Networks
Yekta Demirci, Guillaume Mantelet, Stephane Martel et al. (+2 more)
In Low Earth Orbit (LEO) satellite networks, Beam Hopping (BH) technology enables the efficient utilization of limited
radio resources by adapting to varying user demands and link conditions. Effective BH planning requires prior knowledge of upcoming traffic at the time of scheduling, making
forecasting an important sub-task.
Forecasting becomes particularly critical under heavy load conditions where an unexpected demand burst combined with link degradation may cause buffer overflows and packet loss. To address this challenge, we propose a burst aware
forecasting solution. This challenge may arise in a wide range of wireless networks; therefore, the proposed solution is broadly applicable to settings characterized by bursty traffic patterns where accurate demand
forecasting is essential. Our approach introduces three key enhancements to a
transformer architecture: (i) a distance from the last burst
embedding to capture burst proximity, (ii) two additional linear layers in the decoder to forecast both upcoming bursts and their relative impact, and (iii) use of an asymmetric cost function during model training to better capture burst dynamics. Empirical evaluations in an Earth-fixed
cell under high-traffic demand scenario demonstrate that the proposed model reduces prediction error by up to 94% at a one-step horizon and maintains the ability to accurately capture bursts even near the end of longer prediction horizons following Mean Square Error (MSE) metric.
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All authors Yekta Demirci, Guillaume Mantelet, Stephane Martel, Jean-Francois Frigon, Gunes Karabulut Kurt
Signal Processing
Bit-Efficient Quantisation for Two-Channel Modulo-Sampling Systems
Wenyi Yan, Zeyuan Li, Lu Gan et al. (+2 more)
Two-channel modulo analog-to-digital converters (ADCs) enable high-dynamic-range signal sensing at the Nyquist rate per channel, but existing designs quantise both channel outputs independently, incurring redundant bitrate costs. This paper proposes a bit-efficient quantisation scheme that exploits the integer-valued structure of inter-channel differences, transmitting one quantised channel output together with a compact difference index. We prove that this approach requires only 1-2 bits per signal sample overhead relative to conventional ADCs, despite operating with a much smaller per-channel dynamic range. Simulations confirm the theoretical error bounds and bitrate analysis, while hardware experiments demonstrate substantial bitrate savings compared with existing modulo sampling schemes, while maintaining comparable reconstruction accuracy. These results highlight a practical path towards high-resolution, bandwidth-efficient modulo ADCs for bitrate-constrained systems.
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All authors Wenyi Yan, Zeyuan Li, Lu Gan, Honqing Liu, Guoquan Li
Signal Processing · Cross-listed from cs.IT
Storage-Rate Trade-off in A-XPIR
Mohamed Nomeir and Sennur Ulukus
We consider the storage problem in an asymmetric $X$-secure private information
retrieval (A-XPIR) setting. The A-XPIR setting considers the $X$-secure PIR problem (XPIR) when a given arbitrary set of servers is communicating. We focus on the trade-off region between the average storage at the servers and the average download cost. In the case of $N=4$ servers and two non-overlapping sets of communicating servers with $K=2$ messages, we characterize the achievable region and show that the three main inequalities compared to the no-security case collapse to two inequalities in the asymmetric security case. In the general case, we derive bounds that need to be satisfied for the general achievable region for an arbitrary number of servers and messages. In addition, we provide the storage and
retrieval scheme for the case of $N=4$ servers with $K=2$ messages and two non-overlapping sets of communicating servers, such that the messages are not replicated (in the sense of a coded version of each symbol) and at the same time achieve the optimal achievable rate for the case of replication. Finally, we derive the exact capacity for the case of asymmetric security and asymmetric collusion for $N=4$ servers, with the communication links $\{1,2\}$ and $\{3,4\}$, which splits the servers into two groups, i.e., $g=2$, and with the collusion links $\{1,3\}$, $\{2,4\}$, as $C=\frac{1}{3}$. More generally, we derive a capacity result for a certain family of asymmetric collusion and asymmetric security cases.
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Systems and Control
The Impact of Interference Cognition on the Reliability and Capacity of Industrial Wireless Communications
Yichen Guo, Tao Peng, Yujie Zhao et al. (+2 more)
Interference significantly impacts the performance of industrial wireless networks, particularly n severe interference environments with dense networks reusing spectrum resources intensively. Although delicate interference information is often unavailable in conventional networks, emerging interference cognition techniques can compensate this critical problem with possibly different precision. This paper investigates the relationship between precision of interference cognition and system performance. We propose a novel performance analysis framework that quantifies the impact of varying interference information precision on achievable rate. Specifically, leveraging the Nakagami-$\mathbf{m}$ fading channel model, we analytically and asymptotically analyze the average achievable rate in the finite blocklength regime for different precision levels of signal and interference information. Our findings reveal the critical importance of identifying per-link interference information for achieving optimal performance. Additionally, obtaining instantaneous information is more beneficial for signal links.
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All authors Yichen Guo, Tao Peng, Yujie Zhao, Yijing Niu, Wenbo Wang
Systems and Control
A flexible language model-assisted electronic design automation framework
Cristian Sestito, Panagiota Kontou, Pratibha Verma et al. (+5 more)
Large
language models (LLMs) are transforming electronic design automation (EDA) by enhancing design stages such as schematic design, simulation, netlist synthesis, and place-and-route. Existing methods primarily focus these optimisations within isolated open-source EDA tools and often lack the flexibility to handle multiple domains, such as analogue, digital, and
radio-frequency design. In contrast, modern systems require to interface with commercial EDA environments, adhere to tool-specific operation rules, and incorporate feedback from design outcomes while supporting diverse design flows. We propose a versatile framework that uses LLMs to generate files compatible with commercial EDA tools and optimise designs using power-performance-area reports. This is accomplished by guiding the LLMs with tool constraints and feedback from design outputs to meet tool requirements and user specifications. The framework is used to evaluate case studies on operational transconductance amplifiers, microstrip patch
antennas, and FPGA
circuits.
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All authors Cristian Sestito, Panagiota Kontou, Pratibha Verma, Atish Dixit, Alexandros D. Keros, Michael O'Boyle, Christos-Savvas Bouganis, Themis Prodromakis
Systems and Control
Data-Driven Safe Output Regulation of Strict-Feedback Linear Systems with Input Delay
Zhenxu Zhao, Ji Wang and Weiyao Lan
This paper develops a data-driven safe control framework for linear systems possessing a known strict-feedback structure, but with most plant parameters, external disturbances, and input delay being unknown. By leveraging Koopman operator theory, we utilize Krylov dynamic mode decomposition (DMD) to extract the system dynamics from measured data, enabling the reconstruction of the system and disturbance
matrices. Concurrently, the batch least-squares identification (BaLSI) method is employed to identify other unknown parameters in the input channel. Using control barrier functions (CBFs) and backstepping, we first develop a full-state safe controller. Based on this, we build an output-feedback controller by performing system identification using only the output data and actuation signals as well as constructing an observer to estimate the unmeasured plant states. The proposed approach achieves: 1) finite-time identification of a substantial set of unknown system quantities, and 2) exponential convergence of the output state (the state furthest from the control input) to a reference trajectory while rigorously ensuring safety constraints. The effectiveness of the proposed method is demonstrated through a safe vehicle platooning application.
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Signal Processing
Background Subtraction with Drift Correction for Bistatic Radar Reflectivity Measurements
Alexander Ihlow, Marius Schmidt, Carsten Andrich et al. (+1 more)
Fundamental research on bistatic radar reflectivity is highly relevant, e.g., to the upcoming mobile communication standard 6G, which includes integrated sensing and communication (
ISAC). We introduce a model for correcting instrumentation drift during bistatic radar measurements in anechoic chambers. Usually, background subtraction is applied with the goal to yield the target reflection signal as best as possible while coherently subtracting all signals which were present in both the foreground and background measurement. However, even slight incoherences between the foreground and background measurement process deteriorate the result. We analyze these effects in real measurements in the frequency range 2-18 GHz, taken with the Bistatic Radar (BIRA) measurement facility at TU Ilmenau. Applying our proposed drift correction model, we demonstrate up to 40 dB improvement for the removal of direct line-of-sight
antenna crosstalk over the state of the art.
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All authors Alexander Ihlow, Marius Schmidt, Carsten Andrich, Reiner S. Thomä
Systems and Control · Cross-listed from cs.IT
Utilizing the Perceived Age to Maximize Freshness in Query-Based Update Systems
Sahan Liyanaarachchi, Sennur Ulukus and Nail Akar
Query-based sampling has become an increasingly popular technique for monitoring Markov sources in pull-based update systems. However, most of the contemporary literature on this assumes an exponential distribution for query delay and often relies on the assumption that the feedback or replies to the queries are instantaneous. In this work, we relax both of these assumptions and find optimal sampling policies for monitoring continuous-time Markov chains (CTMC) under generic delay distributions. In particular, we show that one can obtain significant gains in terms of mean binary freshness (MBF) by employing a waiting based strategy for query-based sampling.
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Image and Video Processing · Cross-listed from cs.LG
LLMOrbit: A Circular Taxonomy of Large Language Models -From Scaling Walls to Agentic AI Systems
Badri N. Patro and Vijay S. Agneeswaran
The field of artificial intelligence has undergone a revolution from foundational
Transformer architectures to
reasoning-capable systems approaching human-level performance. We present LLMOrbit, a comprehensive circular taxonomy navigating the landscape of large
language models spanning 2019-2025. This survey examines over 50 models across 15 organizations through eight interconnected orbital dimensions, documenting architectural innovations, training methodologies, and efficiency patterns defining modern LLMs, generative AI, and agentic systems. We identify three critical crises: (1) data scarcity (9-27T
tokens depleted by 2026-2028), (2) exponential cost growth ($3M to $300M+ in 5 years), and (3) unsustainable energy consumption (22x increase), establishing the scaling wall limiting brute-force approaches. Our analysis reveals six paradigms breaking this wall: (1) test-time compute (o1, DeepSeek-R1 achieve GPT-4 performance with 10x inference compute), (2) quantization (4-8x compression), (3) distributed edge computing (10x cost reduction), (4) model merging, (5) efficient training (ORPO reduces
memory 50%), and (6) small specialized models (Phi-4 14B matches larger models). Three paradigm shifts emerge: (1) post-training gains (RLHF, GRPO, pure RL contribute substantially, DeepSeek-R1 achieving 79.8% MATH), (2) efficiency revolution (MoE routing 18x efficiency, Multi-head Latent
Attention 8x KV cache compression enables GPT-4-level performance at $<$$0.30/M
tokens), and (3) democratization (open-source Llama 3 88.6% MMLU surpasses GPT-4 86.4%). We provide insights into techniques (RLHF, PPO, DPO, GRPO, ORPO), trace
evolution from passive generation to tool-using
agents (ReAct, RAG, multi-
agent systems), and analyze post-training innovations.
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Audio and Speech Processing
MATE: Matryoshka Audio-Text Embeddings for Open-Vocabulary Keyword Spotting
Youngmoon Jung, Myunghun Jung, Joon-Young Yang et al. (+3 more)
Open-vocabulary keyword spotting (KWS) with text-based enrollment has emerged as a flexible alternative to fixed-phrase triggers. Prior utterance-level matching methods, from an
embedding-learning standpoint, learn
embeddings at a single fixed dimensionality. We depart from this design and propose Matryoshka Audio-Text
Embeddings (MATE), a dual-encoder framework that encodes multiple
embedding granularities within a single vector via nested sub-
embeddings ("prefixes"). Specifically, we introduce a PCA-guided prefix
alignment: PCA-compressed versions of the full text
embedding for each prefix size serve as teacher targets to align both audio and text prefixes. This
alignment concentrates salient keyword cues in lower-dimensional prefixes, while higher dimensions add detail. MATE is trained with standard deep metric learning objectives for audio-text KWS, and is loss-agnostic. To our knowledge, this is the first application of matryoshka-style
embeddings to KWS, achieving state-of-the-art results on WSJ and LibriPhrase without any inference overhead.
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All authors Youngmoon Jung, Myunghun Jung, Joon-Young Yang, Yong-Hyeok Lee, Jaeyoung Roh, Hoon-Young Cho
Audio and Speech Processing
DAME: Duration-Aware Matryoshka Embedding for Duration-Robust Speaker Verification
Youngmoon Jung, Joon-Young Yang, Ju-ho Kim et al. (+3 more)
Short-utterance speaker verification remains challenging due to limited speaker-discriminative cues in short
speech segments. While existing methods focus on enhancing speaker encoders, the
embedding learning strategy still forces a single fixed-dimensional representation reused for utterances of any length, leaving capacity misaligned with the information available at different durations. We propose Duration-Aware Matryoshka
Embedding (DAME), a model-agnostic framework that builds a nested hierarchy of sub-
embeddings aligned to utterance durations: lower-dimensional representations capture compact speaker traits from short utterances, while higher dimensions encode richer details from longer
speech. DAME supports both training from scratch and fine-tuning, and serves as a direct alternative to conventional large-margin fine-tuning, consistently improving performance across durations. On the VoxCeleb1-O/E/H and VOiCES evaluation sets, DAME consistently reduces the equal error rate on 1-s and other short-duration trials, while maintaining full-length performance with no additional inference cost. These gains generalize across various speaker encoder architectures under both general training and fine-tuning setups.
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All authors Youngmoon Jung, Joon-Young Yang, Ju-ho Kim, Jaeyoung Roh, Chang Woo Han, Hoon-Young Cho
Signal Processing
Achieving Full Multipath Diversity by Random Constellation Rotation: a Theoretical Perspective
Xuehan Wang, Jinhong Yuan, Jintao Wang et al. (+1 more)
Diversity is an essential concept associated with communication reliability in multipath channels since it determines the slope of bit error rate performance in the medium to high signal-to-noise ratio regions. However, most of the existing analytical frameworks were developed for specific modulation schemes while the efficient validation of full multipath diversity for general modulation schemes remains an open problem. To fill this research gap, we propose to utilize random constellation rotation to ease the conditions for full-diversity modulation designs. For linearly precoded cyclic-prefix orthogonal frequency division multiplexing (OFDM) systems, we prove that maximum multipath diversity can be attained as long as the spread
matrix does not have zero entries, which is a sufficient but easily satisfied condition. Furthermore, we derive the sufficient and necessary condition for general modulation schemes, whose verification can be divided into validation tasks for each column of the modulation
matrix. Based on the proposed conditions, maximum diversity order can be attained with the probability of 1 by enabling a randomly generated rotation pattern for both time and doubly dispersive channels. The theoretical analysis in this paper also demonstrates that the diversity evaluation can be concentrated on the pairwise error probability when the number of error symbols is one, which reduces the complexity of diversity-driven design and performance analysis for novel modulation schemes significantly in both time and doubly dispersive channels. Finally, numerical results for various modulation schemes confirm that the theoretical analysis holds in both time and doubly dispersive channels. Furthermore, when employing practical detectors, the random constellation rotation technique consistently enhance the transmission reliability for both coded and uncoded systems.
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All authors Xuehan Wang, Jinhong Yuan, Jintao Wang, Kehan Huang
Image and Video Processing
SHARE: A Fully Unsupervised Framework for Single Hyperspectral Image Restoration
Jiangwei Xie, Zhang Wen, Mike Davies et al. (+1 more)
Hyperspectral image (HSI) restoration is a fundamental challenge in computational imaging and computer
vision. It involves ill-posed inverse problems, such as inpainting and super-resolution. Although deep learning methods have transformed the field through data-driven learning, their effectiveness hinges on access to meticulously curated ground-truth
datasets. This fundamentally restricts their applicability in real-world scenarios where such data is unavailable. This paper presents SHARE (Single Hyperspectral Image Restoration with Equivariance), a fully unsupervised framework that unifies
geometric equivariance principles with low-rank spectral modelling to eliminate the need for ground truth. SHARE's core concept is to exploit the intrinsic invariance of hyperspectral structures under differentiable
geometric transformations (e.g. rotations and scaling) to derive self-supervision signals through equivariance consistency constraints. Our novel Dynamic Adaptive Spectral
Attention (DASA) module further enhances this paradigm shift by explicitly encoding the global low-rank property of HSI and adaptively refining local spectral-spatial correlations through learnable
attention mechanisms. Extensive experiments on HSI inpainting and super-resolution tasks demonstrate the effectiveness of SHARE. Our method outperforms many state-of-the-art unsupervised approaches and achieves performance comparable to that of supervised methods. We hope that our approach will shed new light on HSI restoration and broader scientific imaging scenarios. The code will be released at https://github.com/xuwayyy/SHARE.
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All authors Jiangwei Xie, Zhang Wen, Mike Davies, Dongdong Chen
Image and Video Processing · Cross-listed from cs.CV
Equivariant Learning for Unsupervised Image Dehazing
Zhang Wen, Jiangwei Xie and Dongdong Chen
Image Dehazing (ID) aims to produce a clear image from an observation contaminated by haze. Current ID methods typically rely on carefully crafted priors or extensive haze-free ground truth, both of which are expensive or impractical to acquire, particularly in the context of scientific imaging. We propose a new unsupervised learning framework called Equivariant Image Dehazing (EID) that exploits the
symmetry of image signals to restore clarity to hazy observations. By enforcing haze consistency and systematic equivariance, EID can recover clear patterns directly from raw, hazy images. Additionally, we propose an
adversarial learning strategy to model unknown haze physics and facilitate EID learning. Experiments on two scientific image dehazing
benchmarks (including
cell microscopy and medical endoscopy) and on natural image dehazing have demonstrated that EID significantly outperforms state-of-the-art approaches. By unifying equivariant learning with modelling haze physics, we hope that EID will enable more versatile and effective haze removal in scientific imaging. Code and
datasets will be published.
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Signal Processing
Optimal Calibration of the Endpoint-corrected Hilbert Transform
Eike Osmers and Dorothea Kolossa
Accurate, low-latency estimates of the instantaneous phase of oscillations are essential for closed-loop sensing and actuation, including (but not limited to) phase-locked neurostimulation and other real-time applications. The endpoint-corrected
Hilbert transform (ecHT) reduces boundary artefacts of the
Hilbert transform by applying a causal narrow-band filter to the analytic spectrum. This improves the phase estimate at the most recent sample. Despite its widespread empirical use, the systematic endpoint distortions of ecHT have lacked a principled, closed-form analysis. In this study, we derive the ecHT endpoint operator analytically and demonstrate that its output can be decomposed into a desired positive-frequency term (a deterministic complex gain that induces a calibratable amplitude/phase bias) and a residual leakage term that sets an irreducible variance floor. This yields (i) an explicit characterisation and bounds for endpoint phase/amplitude error, (ii) a mean-squared-error-optimal scalar calibration, and (iii) practical design rules relating window length, filter bandwidth and order, and centre-frequency mismatch to residual bias via an endpoint group delay. The resulting calibrated ecHT achieves near-zero mean phase error and remains computationally compatible with real-time pipelines. Code and analyses are provided at https://github.com/eikeosmers/cecHT.
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Systems and Control
Zero Dynamics Stability of a Multirotor UAV with a Heavy Payload
Sander Doodeman, Paula Chanfreut Palacio, Elena Torta et al. (+1 more)
This paper studies the zero dynamics stability of a multirotor Unmanned Aerial Vehicle (
UAV) carrying a rigidly attached heavy payload. In particular, we focus on controlling the position of a virtual task-relevant point of interest (POI) on the
UAV and investigate how its stability depends on payload placement. Taking the POI position and the yaw angle as output, we prove that the zero dynamics are Lyapunov stable only if this POI is above the system's total center of
gravity, assuming that the POI and the payload are both on the
UAV's body-fixed z-axis. Remarkably, this indicates that when the payload coincides with the POI, zero dynamics stability is only guaranteed if the payload is above the
UAV rather than below it. For the more general case where the POI and payload do not necessarily lie on the same z-axis, we demonstrate stability for a simplified planar model. The analysis also yields an explicit bound on the horizontal payload offset given the rotor thrust limits. Finally, numerical MATLAB simulations provide insight into how results for the planar model are also observed for the general 3D system.
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All authors Sander Doodeman, Paula Chanfreut Palacio, Elena Torta, Duarte Antunes
Audio and Speech Processing
Stream-Voice-Anon: Enhancing Utility of Real-Time Speaker Anonymization via Neural Audio Codec and Language Models
Nikita Kuzmin, Songting Liu, Kong Aik Lee et al. (+1 more)
Protecting speaker identity is crucial for online voice applications, yet streaming speaker anonymization (SA) remains underexplored. Recent research has demonstrated that neural audio codec (NAC) provides superior speaker feature disentanglement and linguistic fidelity. NAC can also be used with causal
language models (LM) to enhance linguistic fidelity and
prompt control for streaming tasks. However, existing NAC-based online LM systems are designed for voice conversion (VC) rather than anonymization, lacking the techniques required for
privacy protection. Building on these advances, we present Stream-Voice-Anon, which adapts modern causal LM-based NAC architectures specifically for streaming SA by integrating anonymization techniques. Our anonymization approach incorporates pseudo-speaker representation sampling, a speaker
embedding mixing and diverse
prompt selection strategies for LM conditioning that leverage the disentanglement properties of quantized content codes to prevent speaker information leakage. Additionally, we compare dynamic and fixed delay configurations to explore latency-
privacy trade-offs in real-time scenarios. Under the VoicePrivacy 2024 Challenge protocol, Stream-Voice-Anon achieves substantial improvements in intelligibility (up to 46% relative WER reduction) and
emotion preservation (up to 28% UAR relative) compared to the previous state-of-the-art streaming method DarkStream while maintaining comparable latency (180ms vs 200ms) and
privacy protection against lazy-informed attackers, though showing 15% relative degradation against semi-informed attackers.
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All authors Nikita Kuzmin, Songting Liu, Kong Aik Lee, Eng Siong Chng
Signal Processing
Deep Reinforcement Learning-Based Dynamic Resource Allocation in Cell-Free Massive MIMO
Phuong Nam Tran, Nhan Thanh Nguyen, Hien Quoc Ngo et al. (+1 more)
In this paper, we consider power allocation and
antenna activation of
cell-free massive multiple-input multiple-output (CFmMIMO) systems. We first derive closed-form expressions for the system spectral efficiency (SE) and energy efficiency (EE) as functions of the power allocation coefficients and the number of active
antennas at the access points (APs). Then, we aim to enhance the EE through jointly optimizing
antenna activation and power control. This task leads to a non-convex and mixed-integer design problem with high-dimensional design variables. To address this, we propose a novel DRL-based framework, in which the
agent learns to map large-scale fading coefficients to AP activation ratio,
antenna coefficient, and power coefficient. These coefficients are then employed to determine the number of active
antennas per AP and the power factors assigned to users based on closed-form expressions. By optimizing these parameters instead of directly controlling
antenna selection and power allocation, the proposed method transforms the intractable optimization into a low-dimensional learning task. Our extensive simulations demonstrate the efficiency and scalability of the proposed scheme. Specifically, in a CFmMIMO system with 40 APs and 20 users, it achieves a 50% EE improvement and 3350 times run time reduction compared to the conventional sequential convex approximation method.
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All authors Phuong Nam Tran, Nhan Thanh Nguyen, Hien Quoc Ngo, Markku Juntti