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arXiv 2024年

作者： Yao, Junteng Lai, Xiazhi Zhi, Kangda Wu, Tuo Jin, Ming Pan, Cunhua Elkashlan, Maged Yuen, Chau Wong, Kai-Kit The Faculty of Electrical Engineering and Computer Science Ningbo University Ningbo315211 China The School of Computer Science Guangdong University of Education Guangdong Guangzhou China The School of Electrical Engineering and Computer Science Technical University of Berlin Berlin10623 Germany The School of Electrical and Electronic Engineering Nanyang Technological University 639798 Singapore The National Mobile Communications Research Laboratory Southeast University Nanjing210096 China The School of Electronic Engineering and Computer Science Queen Mary University of London LondonE1 4NS United Kingdom The Department of Electronic and Electrical Engineering University College London LondonWC1E 6BT United Kingdom The Yonsei Frontier Laboratory the School of Integrated Technology Yonsei University Seoul03722 Korea Republic of

In this paper, we investigate reconfigurable intelligent surface (RIS)-assisted communication systems which involve a fixed-antenna base station (BS) and a mobile user (MU) that is equipped with fluid antenna system (FAS). Specifically, the RIS is utilized to enable communication for the user whose direct link from the base station is blocked by obstacles. We propose a comprehensive framework that provides transmission design for both static scenarios with the knowledge of channel state information (CSI) and harsh environments where CSI is hard to acquire. It leads to two approaches: a CSI-based scheme where CSI is available, and a CSI-free scheme when CSI is inaccessible. Given the complex spatial correlations in FAS, we employ block-diagonal matrix approximation and independent antenna equivalent models to simplify the derivation of outage probabilities in both cases. Based on the derived outage probabilities, we then optimize the throughput of the FAS-RIS system. For the CSI-based scheme, we first propose a gradient ascent-based algorithm to obtain a near-optimal solution. Then, to address the possible high computational complexity in the gradient algorithm, we approximate the objective function and confirm a unique optimal solution accessible through a bisection search method. For the CSI-free scheme, we apply the partial gradient ascent algorithm, reducing complexity further than full gradient algorithms. We also approximate the objective function and derive a locally optimal closed-form solution to maximize throughput. Simulation results validate the effectiveness of the proposed framework for the transmission design in FAS-RIS systems. © 2024, CC BY.

关键词： Antennas

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Beam Scanning for Integrated Sensing and Communication in IRS-aided mmWave Systems 24

Beam Scanning for Integrated Sensing and Communication in IR...

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24th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2023

作者： Li, Renwang Shao, Xiaodan Sun, Shu Tao, Meixia Zhang, Rui Shanghai Jiao Tong University Department of Electronic Engineering Shanghai China Shanghai Jiao Tong University Shanghai Key Laboratory of Digital Media Processing and Transmission Shanghai China The Chinese University of HongKong School of Science and Engineering Shenzhen Research Institute of Big Data Shenzhen China National University of Singapore Department of Electrical and Computer Engineering Singapore

ISBN: (纸本)9781665496261

This paper investigates an intelligent reflecting surface (IRS) aided millimeter-wave integrated sensing and communication (ISAC) system. Specifically, based on the passive beam scanning in the downlink, the IRS finds the optimal beam for reflecting the signals from the base station to a communication user. Meanwhile, the IRS estimates the angle of a nearby target based on its echo signal received by the sensing elements mounted on the IRS (i.e., semi-passive IRS). We propose an ISAC protocol for achieving the above objective via simultaneous (beam) training and sensing (STAS). Then, we derive the achievable rate of the communication user and the Cramer-Rao bound (CRB) of the angle estimation for the sensing target in closed-form. The achievable rate and CRB exhibit different performance against the duration of beam scanning. Specifically, the average achievable rate initially rises and subsequently declines, while the CRB monotonically decreases. Consequently, the duration of beam scanning should be carefully selected to balance communication and sensing performance. Simulation results have verified our analytical findings and shown that, thanks to the efficient use of downlink beam scanning signal for simultaneous communication and target sensing, the STAS protocol outperforms the benchmark protocol with orthogonal beam training and sensing. © 2023 IEEE.

关键词： Millimeter waves

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Covert and Reliable Semantic Communication Against Cross-Layer Privacy Inference over Wireless Edge Networks

Covert and Reliable Semantic Communication Against Cross-Lay...

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IEEE Conference on Wireless Communications and Networking

作者： Rui Xu Gaolei Li Zhaohui Yang Mingzhe Chen Yuchen Liu Jianhua Li School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University China Shanghai Key Laboratory of Integrated Administration Technologies for Information Security Shanghai China College of Information Science and Electronic Engineering Zhejiang University Hangzhou China Electrical and Computer Engineering Department University of Miami USA Department of Computer Science NC State University USA

ISBN: (数字)9798350303582

ISBN: (纸本)9798350303599

Semantic communication has emerged as a revolutionary paradigm within wireless edge networks, showcasing remarkable communication efficiency. In contrast to traditional bit-level communication systems, semantic communication systems exhibit superior effectiveness and precision, particularly in scenarios characterized by low signal-to-noise ratios (SNR). Nonetheless, the privacy of semantic communication poses a critical challenge that demands attention. Once the attacker intercepts the semantic information through continuous eaves-dropping, the private data would be leaked under adversarial environment. Moreover, in low SNR scenario, joint optimization of anti -eavesdropping and privacy reconstruction has not yet been studied, coupled with the intricate nature of designing a cross-layer semantic protection strategy. To address this concern, this paper presents a covert and reliable semantic communication (CRSC) framework via full-duplex receiver to counter continuous eavesdropper by concealing the entire transmission process. Furthermore, a newly-defined metric, namely covert semantic throughput (CST), is introduced to quantify the system's performance. Furthermore, we formulate the maximization of average CST during the semantic transmission period as a multi-constraint optimization problem. Subsequently, we propose a reinforcement learning (RL)-empowered adaptation algorithm to address the formulated problem. Through simulation results, the effectiveness and feasibility of proposed CRSC framework are demonstrated, with an observed maximum average CST improvement of up to 42% compared to conventional communication systems in the low SNR scenario.

关键词： Wireless communication Measurement Simulation Semantics Reinforcement learning Receivers Throughput

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From Missing Pieces to Masterpieces: Image Completion with Context-Adaptive Diffusion

arXiv

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arXiv 2025年

作者： Shamsolmoali, Pourya Zareapoor, Masoumeh Zhou, Huiyu Felsberg, Michael Tao, Dacheng Li, Xuelong Department of Computer Science University of York University of UK SCEE East China Normal University China Department of Electrical Engineering Shanghai Jiao Tong University China School of Computing and Mathematical Sciences University of Leicester United Kingdom Computer Vision Laboratory Linkoping University Sweden College of Computing and Data Science Nanyang Technological University Singapore of China Telecom China

Image completion is a challenging task, particularly when ensuring that generated content seamlessly integrates with existing parts of an image. While recent diffusion models have shown promise, they often struggle with maintaining coherence between known and unknown (missing) regions. This issue arises from the lack of explicit spatial and semantic alignment during the diffusion process, resulting in content that does not smoothly integrate with the original image. Additionally, diffusion models typically rely on global learned distributions rather than localized features, leading to inconsistencies between the generated and existing image parts. In this work, we propose ConFill, a novel framework that introduces a Context-Adaptive Discrepancy (CAD) model to ensure that intermediate distributions of known and unknown regions are closely aligned throughout the diffusion process. By incorporating CAD, our model progressively reduces discrepancies between generated and original images at each diffusion step, leading to contextually aligned completion. Moreover, ConFill uses a new Dynamic Sampling mechanism that adaptively increases the sampling rate in regions with high reconstruction complexity. This approach enables precise adjustments, enhancing detail and integration in restored areas. Extensive experiments demonstrate that ConFill outperforms current methods, setting a new benchmark in image completion. © 2025, CC BY-SA.

关键词： Photointerpretation

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Modified Kelvin-Voigt fractional derivative model for viscoelasticity measurement in optical coherence elastography

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Chinese Optics Letters 2025年第1期23卷 93-101页

作者： Chenming Yang Zhongliang Li Nan Nan Teng Liu Yaoli Luo Xiangzhao Wang Advanced Light Source and System R&D Center Department of Advanced Optical and Microelectronic EquipmentShanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China State Key Laboratory of Extreme Photonics and Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

Optical coherence elastography(OCE)can quantitatively obtain the viscoelasticity of tissues using rheological models and is widely applied to the clinical diagnosis of ***,commonly used rheological models in OCE do not account for the distinctive dependence of high-frequency storage and loss moduli on frequency in tissues,which results in the rheological models failing to accurately measure the viscoelastic properties of *** this paper,a modified Kelvin-Voigt fractional derivative model is presented based on the power-law behavior of soft tissues and the dependence of high-frequency complex shear modulus on frequency in living *** the rheometer and OCE tests,the modified model can provide the prediction of the power-law relationship between the low-frequency shear viscosity and frequency;compared with the Kelvin-Voigt and Kelvin-Voigt fractional derivative models,the modified model has a higher goodness-of-fit(accuracy>96%)for the high-frequency storage moduli of gelatin ***,the proposed model can reduce the root mean square error of fit by approximately 83%for the high-frequency(1–128 kHz)storage modulus of the polydimethylsiloxane phantoms obtained from publicly available ***,the modified model accurately predicts the mechanical properties of biomimetic materials over a wide frequency range,with the potential to more accurately reflect pathological changes in tissues.

关键词： optical coherence tomography optical coherence elastography viscoelasticity rheological model

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Comparing YOLO-based Detectors for Pedestrian and Car Detection in Aerial Static Video: An Evaluation of Generalization Capacity and Performance

Comparing YOLO-based Detectors for Pedestrian and Car Detect...

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IEEE International Workshop on Imaging Systems and Techniques (IST)

作者： Georgios Tzedakis Eleftheria Tzamali Emmanouil G. Spanakis Marios Antonakakis Michalis Zervakis Vangelis Sakkalis Computational Biomedicine Laboratory Institute of Computer Science Foundation for Research and Technology Hellas (FORTH) Heraklion Greece School of Electrical and Computer Engineering Technical University of Crete (TUC) Chania Greece

Over the last decades, the famous deep-learning framework of ‘You Only Look Once’ – YOLO for object detection has gasped important interest due to its vital performance for object detection. In this paper, we compare three deep learning architectures of YOLO family for the task of pedestrian and car detection from static video frames. We have chosen YOLOv5s, YOLOv5su, and YOLOv8s architectures as they can perform real-time detection, which is the focus of our study. Our training and evaluation were conducted on a dataset from Stanford University, which includes a combination of eight birds-eye view scenes. The dataset was separated into train, validation, and test sets, and the discrepancies between validation and test results were used to evaluate the generalization capacity of each architecture. For the purpose of evaluating the generalization capacity of the model, we isolated one scene as the test set, ensuring it was not seen during the training phase. Our experimental results show that the recent YOLOv5su and YOLOv8s do not outperform YOLOv5s in terms of accuracy and generalization despite their anchorless architecture. The challenges faced by all the architectures in terms of generalization can be ascribed to a combination of factors, namely the model's capability to differentiate the background and the static characteristics of the dataset frames.

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Transmissive RIS-Empowered LEO-Satellite Communications With Hybrid-NOMA Under Residual Hardware Impairments

IEEE Transactions on Green Communications and Networking

引用

IEEE Transactions on Green Communications and Networking 2024年

作者： Asif, Muhammad Bao, Xu Ali, Zain Ihsan, Asim Ahmed, Manzoor Li, Xingwang Jiangsu University School of Computer Science and Communication Engineering Zhenjiang China University of California Department of Electrical and Computer Engineering Santa CruzCA United States University of Cambridge Department of Engineering CambridgeCB3 0FA United Kingdom Hubei Engineering University School of Computer and Information Science The Institute for AI Industrial Technology Research Xiaogan432000 China Henan Polytechnic University School of Physics and Electronic Information Engineering China Jiaozuo Key Laboratory of Crow-Sensing Network Jiaozuo454003 China

This manuscript introduces an efficient resource allocation framework for a transmissive reconfigurable intelligent surface (T-RIS) assisted Low Earth Orbit (LEO) satellite non-orthogonal multiple access (NOMA) system under residual hardware impairments (RHIs) resulting from imperfect transceiver hardware design. In particular, the goal is to maximize the sum rate of the considered multi-cluster based T-RIS assisted LEO-satellite NOMA network. This is achieved by optimizing the power-allocation of users, time-allocation for each cluster, and transmit passive beamforming of T-RIS node, while adhering to quality-of-service (QoS), time-allocation, and power-budget constraints. Moreover, the presented optimization algorithm tackles the considered highly non-convex problem in three steps. Firstly, the power-allocation of NOMA users is computed by exploiting Lagrange duality and sub-gradient methods. Secondly, the time-allocation for each cluster is determined based on the interior point method by exploiting Mosek-assisted CVX toolbox. Thirdly, the computation of passive beamforming employs semi-definite programming (SDP) and successive convex approximation (SCA) techniques, where a rank-1 solution is achieved by incorporating the Gaussian randomization method. Finally, numerical simulations affirm the effectiveness of the proposed optimization strategy, highlighting its superior performance in comparison to benchmark techniques. Notably, it proves to be highly effective in achieving fast convergence with only a few iterations. © 2017 IEEE.

关键词： Budget control

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From Circuits to SoC Processors: Arithmetic Approximation Techniques & Embedded Computing Methodologies for DSP Acceleration

arXiv

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arXiv 2023年

作者： Leon, Vasileios K. National Technical University of Athens School of Electrical and Computer Engineering Division of Computer Science Microprocessors and Digital Systems Laboratory 9 Heroon Polytechniou Zografou Campus Athens15780 Greece

The recent end of Dennard’s Scaling and the declining Moore’s Law have signified a new era for computing systems. Power efficiency has now become a critical factor for both cloud and edge computing. Concurrently, the rapid growth of compute-intensive applications from the Digital Signal Processing (DSP) and Artificial Intelligence (AI) domains challenges the resources of computing systems. As a result, the computing industry is forced to find alternative design approaches and computing platforms to sustain increased power efficiency, while providing sufficient performance. Among the examined solutions, Approximate Computing, Hardware Acceleration, and Heterogeneous Computing have gained great momentum. Approximate Computing is a novel design paradigm that exploits the inherent error resilience of DSP/AI applications to deliver gains in power, area, and/or performance by reducing the quality of the results. Hardware Acceleration refers to the execution of demanding computational tasks on specialized hardware, such as the Application-Specific Integrated Circuits (ASICs) and the Field-Programmable Gate Arrays (FPGAs), rather than general-purpose processors. Finally, Heterogeneous Computing refers to versatile processing architectures, such as the vision Processing Units (VPUs), which integrate more than one type of processor and various memory technologies. In this Dissertation, we introduce design solutions and methodologies, built on top of the preceding computing paradigms, for the development of energy-efficient DSP and AI accelerators. In particular, we adopt the promising paradigm of Approximate Computing and apply new approximation techniques in the design of arithmetic circuits. Based on our methodology, these arithmetic approximation techniques are then combined with hardware design techniques to implement approximate ASIC- and FPGA-based DSP and AI accelerators. Moreover, we propose methodologies for the efficient mapping of DSP/AI kernels on distinctive embe

关键词： Digital signal processing

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Gradient Descent with Low-Rank Objective Functions

Gradient Descent with Low-Rank Objective Functions

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IEEE Conference on Decision and Control

作者： Romain Cosson Ali Jadbabaie Anuran Makur Amirhossein Reisizadeh Devavrat Shah Inria Paris France Laboratory for Information & Decision Systems MIT Cambridge MA USA Department of Computer Science School of Electrical & Computer Engineering Purdue University West Lafayette IN USA

Several recent empirical studies demonstrate that important machine learning tasks, e.g., training deep neural networks, exhibit low-rank structure, where the loss function varies significantly in only a few directions of the input space. In this paper, we leverage such low-rank structure to reduce the high computational cost of canonical gradient-based methods such as gradient descent (GD). Our proposed Low-Rank Gradient Descent (LRGD) algorithm finds an $\epsilon$ -minimizer of a p-dimensional function by first identifying $r\leq p$ significant directions, and then estimating the true p-dimensional gradient at every iteration by computing directional derivatives only along those $r$ directions. We establish that the “directional oracle complexity” of LRGD for strongly convex objective functions is $\mathrm{O}(r\log(1/\epsilon)+rp)$ . Therefore, when $r\ll p$ , LRGD provides significant improvement over the known complexity of $\mathcal{O}(p\log(1/\epsilon))$ of GD in the strongly convex setting. Furthermore, using real and synthetic data, we empirically find that LRGD provides significant gains over GD when the data has low-rank structure, and in the absence of such structure, LRGD does not degrade performance compared to GD.

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Slow electron-phonon relaxation controls the dynamics of the superconducting resistive transition

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Physical Review B 2024年第10期110卷 104519页

作者： E. M. Baeva A. I. Kolbatova N. A. Titova S. Saha A. Boltasseva S. Bogdanov V. M. Shalaev A. V. Semenov A. Levchenko G. N. Goltsman V. S. Khrapai Moscow 119435 Russian Federation 20 Myasnitskaya Street Moscow 101000 Russian Federation Laboratory of Photonic Gas Sensors University of Science and Technology MISIS Moscow 119049 Russian Federation Birck Nanotechnology Center and Elmore Family School of Electrical and Computer Engineering Department of Electrical and Computer Engineering Holonyak Micro and Nanotechnology Laboratory Illinois Quantum Information Science and Technology Center Moscow Institute of Physics and Technology Dolgoprudny 141701 Russian Federation Department of Physics Moscow 121205 Russian Federation Osipyan

We investigate the temporal and spatial scales of resistance fluctuations (R fluctuations) at the superconducting resistive transition accessed through voltage fluctuation measurements in thin epitaxial TiN films. This material is characterized by slow electron-phonon relaxation, which puts it far beyond the applicability range of the textbook scenario of superconducting fluctuations. The measured Lorentzian spectrum of the R fluctuations identifies their correlation time, which is nearly constant across the transition region and has no relation to the conventional Ginzburg-Landau timescale. Instead, the correlation time coincides with the energy relaxation time determined by a combination of the electron-phonon relaxation and the relaxation via diffusion into reservoirs. Our data are quantitatively consistent with the model of spontaneous temperature fluctuations and highlight the lack of understanding of the resistive transition in materials with slow electron-phonon relaxation.

关键词： Critical phenomena Fluctuations & noise Phonons Superconducting fluctuations Superconducting phase transition Low-temperature superconductors Thin films Resistivity measurements

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