Signal Processing
Backscatter-Assisted High-Speed Rail Communications in Straight Tunnel Environments: Effects of Tag Number and Phase Control
Yunping Mu, Gongpu Wang, Ruisi He et al. (+3 more)
Backscatter communication is a promising technology to enhance the signal strength received by the receiver in straight tunnel environments. The impact of the number of tags and their phase adjustment on system performance remains a challenging issue though. Therefore, in this paper, we investigate the channel gain of backscatter-assisted communication with multiple tags in straight tunnels. In particular, we derive the probabilities that the backscatter link gain is greater than the direct link under adjustable and random phase assumptions by applying the Gaussian and Gamma approximations to derive tractable expressions. The simulation results show that phaseadjustable tags significantly improve the channel gain of the backscatter links compared to the random phase case. Moreover, the number of tags has an upper threshold for an effective tag deployment pattern. These insights provide valuable guidelines for the efficient design of backscatter communication systems in tunnel environments.
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All authors Yunping Mu, Gongpu Wang, Ruisi He, Theodoros A. Tsiftsis, Saman Atapattu, Chintha Tellambura
Signal Processing
Beam-Brainstorm: A Generative Site-Specific Beamforming Approach
Zihao Zhou, Zhaolin Wang and Yuanwei Liu
Accurately understanding the propagation environment is a fundamental challenge in site-specific beamforming (SSBF). This paper proposes a novel generative SSBF (GenSSBF) solution, which represents a paradigm shift from conventional unstructured prediction to joint-structure modeling. First, considering the fundamental differences between beam generation and conventional image synthesis, a unified GenSSBF framework is proposed, which includes a site profile, a wireless prompting module, and a generator. Second, a beam-brainstorm (BBS) solution is proposed as an instantiation of this GenSSBF framework. Specifically, the site profile is configured by transforming channel data from spatial domain to a reversible latent space via discrete
Fourier transform (DFT). To facilitate practical deployment, the wireless
prompt is constructed from the reference signal received power (RSRP) measured using a small number of DFT-beams. Finally, the generator is developed using a customized conditional
diffusion model. Rather than relying on a meticulously designed global codebook, BBS directly generates diverse and high-fidelity user-specific beams guided by the wireless
prompts. Simulation results on accurate ray-tracing
datasets demonstrate that BBS can achieve near-optimal beamforming gain while drastically reducing the beam sweeping overhead, even in low signal-to-noise ratio (SNR) environments.
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Audio and Speech Processing · Cross-listed from cs.CL
Towards Multi-Level Transcript Segmentation: LoRA Fine-Tuning for Table-of-Contents Generation
Steffen Freisinger, Philipp Seeberger, Thomas Ranzenberger et al. (+2 more)
Segmenting
speech transcripts into thematic sections benefits both downstream processing and users who depend on written text for accessibility. We introduce a novel approach to hierarchical topic
segmentation in transcripts, generating multi-level tables of contents that capture both topic and subtopic boundaries. We compare zero-shot prompting and LoRA fine-tuning on large
language models, while also exploring the integration of high-level
speech pause features. Evaluations on English meeting recordings and
multilingual lecture transcripts (Portuguese, German) show significant improvements over established topic
segmentation baselines. Additionally, we adapt a common evaluation measure for multi-level
segmentation, taking into account all hierarchical levels within one metric.
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All authors Steffen Freisinger, Philipp Seeberger, Thomas Ranzenberger, Tobias Bocklet, Korbinian Riedhammer
Systems and Control
Finite-State Decentralized Policy-Based Control With Guaranteed Ground Coverage
Hossein Rastgoftar
We propose a finite-state, decentralized decision and control framework for multi-
agent ground coverage. The approach decomposes the problem into two coupled components: (i) the structural design of a deep neural network (DNN) induced by the reference configuration of the
agents, and (ii) policy-based decentralized coverage control.
Agents are classified as anchors and followers, yielding a generic and scalable communication architecture in which each follower interacts with exactly three in-neighbors from the preceding layer, forming an enclosing triangular communication structure. The DNN training weights implicitly encode the spatial configuration of the
agent team, thereby providing a
geometric representation of the environmental target set. Within this architecture, we formulate a computationally efficient decentralized Markov decision process (MDP) whose components are time-invariant except for a time-varying cost function defined by the deviation from the centroid of the target set contained within each
agent communication triangle. By introducing the concept of Anyway Output Controllability (AOC), we assume each
agent is AOC and establish decentralized convergence to a desired configuration that optimally represents the environmental target.
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Audio and Speech Processing
Towards Prosodically Informed Mizo TTS without Explicit Tone Markings
Abhijit Mohanta, Remruatpuii, Priyankoo Sarmah et al. (+2 more)
This paper reports on the development of a text-to-
speech (TTS) system for Mizo, a low-resource tonal
language of the Tibeto-Burman family, spoken primarily in the Indian state of Mizoram. The TTS was built using only 5.18 hours of data; however, based on subjective and objective evaluations, the outputs were considered perceptually acceptable and intelligible. A baseline Tacotron2 model was built, and then, using the same data, another TTS model was built with VITS. VITS achieved significantly lower Mel-Cepstral Distortion (MCD) and significantly higher subjective ratings than Tacotron2, although the differences in DNSMOS, F0 RMSE, and F0 correlation were not statistically significant. In terms of tone synthesis, the VITS model showed numerically lower tone errors than the Tacotron2 model. The paper demonstrates that a non-autoregressive, end-to-end framework can achieve synthesis of acceptable perceptual quality and intelligibility.
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All authors Abhijit Mohanta, Remruatpuii, Priyankoo Sarmah, Rohit Sinha, Wendy Lalhminghlui
Systems and Control · Cross-listed from cs.AR
Ageing Monitoring for Commercial Microcontrollers Based on Timing Windows
Leandro Lanzieri, Jiri Kral, Goerschwin Fey et al. (+2 more)
Microcontrollers are increasingly present in embedded deployments and dependable systems, for which malfunctions due to hardware ageing can have severe impact. The lack of deployable techniques for ageing monitoring on these devices has spread the application of guard bands to prevent timing errors due to degradation. Applying this static technique can limit performance and lead to sudden failures as devices age. In this paper, we follow a software-based self-testing approach to design monitoring of hardware degradation for microcontrollers. Deployable in the field, our technique leverages timing windows of variable lengths to determine the maximum operational frequency of the devices. We empirically validate the method on real hardware and find that it consistently detects temperature-induced degradations in maximum operating frequency of up to 13.79 % across devices for 60 {\deg}C temperature increase.
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All authors Leandro Lanzieri, Jiri Kral, Goerschwin Fey, Holger Schlarb, Thomas C. Schmidt
Signal Processing
Doppler-Resilient LEO Satellite OFDM Transmission with Affine Frequency Domain Pilot
Shuntian Tang, Xiaomei Wu, Xinyi Wang et al. (+5 more)
Orthogonal frequency division multiplexing (OFDM) based low Earth orbit (LEO) satellite communication system suffers from severe Doppler shifts, while {the Doppler-resilient affine frequency-division multiplexing (AFDM) transmission suffers from significantly high processing complexity in data detection}. In this paper, we explore the channel estimation gain of affine frequency (AF) domain pilot to enhance the OFDM transmission under high mobility. Specifically, we propose a novel AF domain pilot
embedding scheme for satellite-ground downlink OFDM systems for capturing the channel characteristics. By exploiting the autoregressive (AR) property of adjacent channels, a long short-term
memory (LSTM) based predictor is designed to replace conventional interpolation operation in OFDM channel estimation. Simulation results show that the proposed transmission scheme significantly outperforms conventional OFDM scheme in terms of bit error rate (BER) under high Doppler scenarios, thus paving a new way for the design of next generation non-terrestrial network (NTN) communication systems.
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All authors Shuntian Tang, Xiaomei Wu, Xinyi Wang, Le Zhao, Guang Yang, Zilong Liu, Fan Liu, Zesong Fei
Systems and Control
Asymptotic Behavior of an Unforced Duhem-Type Hysteretic Oscillator
Mihails Milehins and Dan B. Marghitu
The article describes fundamental analytical properties of an unforced mechanical oscillator with a Duhem-type viscoelastoplastic hysteretic element. These properties include global existence of solutions, uniqueness of solutions, and convergence of each solution to an
equilibrium point.
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Systems and Control
Policy Optimization with Differentiable MPC: Convergence Analysis under Uncertainty
Riccardo Zuliani, Efe C. Balta and John Lygeros
Model-based policy optimization is a well-established framework for designing reliable and high-performance controllers across a wide range of control applications. Recently, this approach has been extended to model predictive control policies, where explicit dynamical models are embedded within the control law. However, the performance of the resulting controllers, and the convergence of the associated optimization
algorithms, critically depends on the accuracy of the models. In this paper, we demonstrate that combining gradient-based policy optimization with recursive system identification ensures convergence to an optimal controller design and showcase our finding in several control examples.
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Audio and Speech Processing
MORE: Multi-Objective Adversarial Attacks on Speech Recognition
Xiaoxue Gao, Zexin Li, Yiming Chen et al. (+1 more)
The emergence of large-scale automatic
speech recognition (ASR) models such as Whisper has greatly expanded their adoption across diverse real-world applications. Ensuring robustness against even minor input perturbations is therefore critical for maintaining reliable performance in real-time environments. While prior work has mainly examined accuracy degradation under
adversarial attacks, robustness with respect to efficiency remains largely unexplored. This narrow focus provides only a partial understanding of ASR model vulnerabilities. To address this gap, we conduct a comprehensive study of ASR robustness under multiple attack scenarios. We introduce MORE, a multi-objective repetitive doubling encouragement attack, which jointly degrades recognition accuracy and inference efficiency through a hierarchical staged repulsion-anchoring mechanism. Specifically, we reformulate multi-objective
adversarial optimization into a hierarchical framework that sequentially achieves the dual objectives. To further amplify effectiveness, we propose a novel repetitive encouragement doubling objective (REDO) that induces duplicative text generation by maintaining accuracy degradation and periodically doubling the predicted sequence length. Overall, MORE compels ASR models to produce incorrect transcriptions at a substantially higher computational cost, triggered by a single
adversarial input. Experiments show that MORE consistently yields significantly longer transcriptions while maintaining high word error rates compared to existing baselines, underscoring its effectiveness in multi-objective
adversarial attack.
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All authors Xiaoxue Gao, Zexin Li, Yiming Chen, Nancy F. Chen
Signal Processing
On the Performance of Lossless Reciprocal MiLAC Architectures in Multi-User Networks
Tianyu Fang, Xiaohua Zhou and Yijie Mao
Microwave linear analog computer (MiLAC)-aided beamforming, which processes the transmitted symbols fully in the analog domain, has recently emerged as a promising alternative to fully digital and hybrid beamforming architectures for multiple-input multiple-output (
MIMO) systems. While prior studies have shown that lossless and reciprocal MiLAC can achieve the same capacity as digital beamforming in a single-user
MIMO network, its performance in multi-user scenarios remains unknown. To answer this question, in this work, we establish a downlink multi-user multiple-input single-output (MU-MISO) network with a MiLAC-aided transmitter, and investigate its sum-rate performance. Based on the microwave network theory, we first prove that lossless and reciprocal MiLAC cannot achieve the same performance as digital beamforming in a general MU-MISO network. Then, we formulate a sum-rate maximization problem and develop an efficient optimization framework to jointly optimize the power allocation and the scattering
matrix for MiLAC. Numerical results validate our theoretical analysis and demonstrate that MiLAC is a promising architecture for future extremely large-scale
MIMO systems.
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Signal Processing · Cross-listed from math.ST
Pathwise Representation of the Smoothing Distribution in Continuous-Time Linear Gaussian Models
Masahiro Kurisaki
We study the filtering and smoothing problem for continuous-time linear Gaussian systems. While classical approaches such as the Kalman-Bucy filter and the Rauch-Tung-Striebel (RTS) smoother provide recursive formulas for the conditional mean and covariance, we present a pathwise perspective that characterizes the smoothing error dynamics as an Ornstein-Uhlenbeck process. As an application, we show that standard filtering and smoothing equations can be uniformly derived as corollaries of our main
theorem. In particular, we provide the first mathematically rigorous derivation of the Bryson-Frazier smoother in the continuous-time setting. Beyond offering a more transparent understanding of the smoothing distribution, our formulation enables pathwise sampling from it, which facilitates Monte Carlo methods for evaluating nonlinear functionals.
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Systems and Control · Cross-listed from cs.LG
Distributed Federated Learning by Alternating Periods of Training
Shamik Bhattacharyya and Rachel Kalpana Kalaimani
Federated learning is a
privacy-focused approach towards machine learning where models are trained on client devices with locally available data and aggregated at a central server. However, the dependence on a single central server is challenging in the case of a large number of clients and even poses the risk of a single point of failure. To address these critical limitations of scalability and fault-tolerance, we present a distributed approach to
federated learning comprising multiple servers with inter-server communication capabilities. While providing a fully decentralized approach, the designed framework retains the core
federated learning structure where each server is associated with a disjoint set of clients with server-client communication capabilities. We propose a novel DFL (Distributed
Federated Learning)
algorithm which uses alternating periods of local training on the client data followed by global training among servers. We show that the DFL
algorithm, under a suitable choice of parameters, ensures that all the servers converge to a common model value within a small tolerance of the ideal model, thus exhibiting effective integration of local and global training models. Finally, we illustrate our theoretical claims through numerical simulations.
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Signal Processing
Rethinking Secure Semantic Communications in the Age of Generative and Agentic AI: Threats and Opportunities
Shunpu Tang, Yuanyuan Jia, Zijiu Yang et al. (+6 more)
Semantic communication (SemCom) improves communication efficiency by transmitting task-relevant information instead of raw bits and is expected to be a key technology for 6G networks. Recent advances in generative AI (GenAI) further enhance SemCom by enabling robust semantic encoding and decoding under limited channel conditions. However, these efficiency gains also introduce new security and
privacy vulnerabilities. Due to the broadcast nature of wireless channels, eavesdroppers can also use powerful GenAI-based semantic decoders to recover private information from intercepted signals. Moreover, rapid advances in agentic AI enable eavesdroppers to perform long-term and adaptive inference through the integration of
memory, external knowledge, and
reasoning capabilities. This allows eavesdroppers to further infer user private behavior and intent beyond the transmitted content. Motivated by these emerging challenges, this paper comprehensively rethinks the security and
privacy of SemCom systems in the age of generative and agentic AI. We first present a systematic taxonomy of eavesdropping threat models in SemCom systems. Then, we provide insights into how GenAI and agentic AI can enhance eavesdropping threats. Meanwhile, we also highlight potential opportunities for leveraging GenAI and agentic AI to design
privacy-preserving SemCom systems.
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All authors Shunpu Tang, Yuanyuan Jia, Zijiu Yang, Qianqian Yang, Ruichen Zhang, Jun Du, Jihong Park, Zhiguo Shi, Jiming Chen
Image and Video Processing · Cross-listed from cs.CV
DDNet: A Dual-Stream Graph Learning and Disentanglement Framework for Temporal Forgery Localization
Boyang Zhao, Xin Liao, Jiaxin Chen et al. (+2 more)
The rapid
evolution of AIGC technology enables misleading viewers by tampering mere small segments within a
video, rendering
video-level detection inaccurate and unpersuasive. Consequently, temporal forgery localization (TFL), which aims to precisely pinpoint tampered segments, becomes critical. However, existing methods are often constrained by local view, failing to capture global anomalies. To address this, we propose a \underline{d}ual-stream graph learning and \underline{d}isentanglement framework for temporal forgery localization (DDNet). By coordinating a Temporal Distance Stream for local artifacts and a Semantic Content Stream for long-range connections, DDNet prevents global cues from being drowned out by local smoothness. Furthermore, we introduce Trace Disentanglement and Adaptation (TDA) to isolate generic forgery fingerprints, alongside Cross-Level Feature
Embedding (CLFE) to construct a robust feature foundation via deep fusion of hierarchical features. Experiments on ForgeryNet and TVIL
benchmarks demonstrate that our method outperforms state-of-the-art approaches by approximately 9% in AP@0.95, with significant improvements in cross-domain robustness.
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All authors Boyang Zhao, Xin Liao, Jiaxin Chen, Xiaoshuai Wu, Yufeng Wu
Systems and Control · Cross-listed from quant-ph
A Survey on Applications of Quantum Computing for Unit Commitment
Milad Hasanzadeh, Ali Rajabi and Amin Kargarian
Unit Commitment (UC) is a core optimization problem in power system operation and electricity
market scheduling. It determines the optimal on/off status and dispatch of generating units while satisfying system, operational, and
market constraints. Traditionally, UC has been solved using mixed-integer programming, dynamic programming, or metaheuristic methods, all of which face scalability challenges as systems grow in size and uncertainty. Recent advances in
quantum computing, spanning
quantum annealing, variational
algorithms, and hybrid
quantum classical optimization, have opened new opportunities to accelerate UC solution processes by exploiting
quantum parallelism and
entanglement. This paper presents a comprehensive survey of existing research on the applications of
quantum computing for solving the UC problem. The reviewed works are categorized based on the employed
quantum paradigms, including annealing-based, variational hybrid,
quantum machine learning, and
quantum-inspired methods. Key modeling strategies, hardware implementations, and computational trade-offs are discussed, highlighting the current progress, limitations, and potential future directions for large-scale
quantum-enabled UC.
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Signal Processing
Joint Sparsity and Beamforming Design for RDARS-Aided Systems
Chengwang Ji, Haiquan Lu, Qiaoyan Peng et al. (+2 more)
Reconfigurable distributed
antennas and reflecting surface (RDARS) has emerged as a promising architecture for communication and sensing performance enhancement. In particular, the new selection gain can be achieved by leveraging the dynamic working mode selection between connection and reflection modes, whereas low-complexity element configuration remains an open issue. In this paper, we consider a RDARS-assisted communication system, where the connected elements are formed as a uniform sparse array for simplified mode configuration while achieving enlarged physical array aperture. The sum rate maximization problem is then formulated by jointly optimizing the active and passive beamforming
matrices and sparsity of connected element array. For the special cases of a single user equipment (UE) and two UEs, the optimal sparsity designs are derived in closed-form. Then, for an arbitrary number of UEs, a weighted minimum mean-square error-based alternating optimization (AO)
algorithm is proposed to tackle the non-convex optimization problem. Numerical results demonstrate the importance of optimizing the sparsity and the effectiveness of low-complexity sparsity optimization.
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All authors Chengwang Ji, Haiquan Lu, Qiaoyan Peng, Jintao Wang, Shaodan Ma
Systems and Control · Cross-listed from cs.HC
Design and Quantitative Evaluation of an Embedded EEG Instrumentation Platform for Real-Time SSVEP Decoding
Manh-Dat Nguyen, Thomas Do, Nguyen Thanh Trung Le et al. (+3 more)
This paper presents an embedded
EEG instrumentation platform for real-time steady-state visually evoked potential (SSVEP) decoding based on an ESP32-S3 microcontroller and an ADS1299 analog front end. The system performs $8$-channel
EEG acquisition, zero-phase bandpass filtering, and canonical correlation analysis entirely on-device, while supporting wireless communication and closed-loop operation without external computation. A central contribution is the quantitative characterization of the platform's measurement integrity. Reported results demonstrate a stable shorted-input noise floor ($\approx 0.08~\mu\text{V}_{\text{RMS}}$), tightly bounded sampling jitter ($0.56~\mu\text{s}$ standard deviation), and negligible long-term drift ($< 1~\text{ppm}$). Numerical fidelity analysis shows $100\%$ decision agreement between the mixed-precision embedded pipeline and a $64$-bit double-precision reference. Effective common-mode attenuation exceeded $112~\text{dB}$ under balanced conditions, with a localized $26.9~\text{dB}$ degradation observed under source-impedance mismatch. Closed-loop validation achieved $99.17\%$ online accuracy and an information transfer rate of $27.66~\text{bits/min}$. These results position the proposed system as a quantitatively characterized embedded
EEG measurement and processing platform for real-time SSVEP decoding.
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All authors Manh-Dat Nguyen, Thomas Do, Nguyen Thanh Trung Le, Xuan-The Tran, Fred Chang, Chin-Teng Lin
Image and Video Processing
Robust Deep Joint Source-Channel Coding for Video Transmission over Multipath Fading Channel
Bohuai Xiao, Jian Zou, Fanyang Meng et al. (+2 more)
To address the challenges of wireless
video transmission over multipath fading channels, we propose a robust deep joint source-channel coding (DeepJSCC) framework by effectively exploiting temporal redundancy and incorporating robust innovations at the modulation, coding, and decoding stages. At the modulation stage, tailored orthogonal frequency division multiplexing (OFDM) for robust
video transmission is employed, decomposing wideband signals into orthogonal frequency-flat sub-channels to effectively mitigate frequency-selective fading. At the coding stage, conditional contextual coding with multi-scale Gaussian warped features is introduced to efficiently model temporal redundancy, significantly improving reconstruction quality under strict bandwidth constraints. At the decoding stage, a lightweight denoising module is integrated to robustly simplify signal restoration and accelerate convergence, addressing the suboptimality and slow convergence typically associated with simultaneously performing channel estimation, equalization, and semantic reconstruction. Experimental results demonstrate that the proposed robust framework significantly outperforms state-of-the-art
video DeepJSCC methods, achieving an average reconstruction quality gain of 5.13 dB under challenging multipath fading channel conditions.
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All authors Bohuai Xiao, Jian Zou, Fanyang Meng, Wei Liu, Yongsheng Liang
Systems and Control · Cross-listed from cs.RO
Simulations and Advancements in MRI-Guided Power-Driven Ferric Tools for Wireless Therapeutic Interventions
Wenhui Chu, Aobo Jin and Hardik A. Gohel
Designing a robotic system that functions effectively within the specific environment of a
Magnetic Resonance Imaging (MRI) scanner requires solving numerous technical issues, such as maintaining the
robot's precision and stability under strong
magnetic fields. This research focuses on enhancing MRI's role in medical imaging, especially in its application to guide intravascular interventions using
robot-assisted devices. A newly developed computational system is introduced, designed for seamless integration with the MRI scanner, including a computational unit and user interface. This system processes MR images to delineate the vascular network, establishing virtual paths and boundaries within vessels to prevent procedural damage. Key findings reveal the system's capability to create tailored
magnetic field gradient patterns for device control, considering the vessel's geometry and safety norms, and adapting to different blood flow characteristics for finer
navigation. Additionally, the system's modeling aspect assesses the safety and feasibility of navigating pre-set vascular paths. Conclusively, this system, based on the Qt framework and C/C++, with specialized software modules, represents a major step forward in merging imaging technology with robotic aid, significantly enhancing precision and safety in intravascular procedures.
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