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Age-Optimal Cached Distribution in the Satellite-Integrated Internet of Things via Cross-Slot Directed Graph
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作者 Hu Zhouyong Li Yue +1 位作者 Zhang Hanxu Yang Zhihua 《China Communications》 2025年第6期300-318,共19页
In the Satellite-integrated Internet of Things(S-IoT),data freshness in the time-sensitive scenarios could not be guaranteed over the timevarying topology with current distribution strategies aiming to reduce the tran... In the Satellite-integrated Internet of Things(S-IoT),data freshness in the time-sensitive scenarios could not be guaranteed over the timevarying topology with current distribution strategies aiming to reduce the transmission delay.To address this problem,in this paper,we propose an age-optimal caching distribution mechanism for the high-timeliness data collection in S-IoT by adopting a freshness metric,as called age of information(AoI)through the caching-based single-source multidestinations(SSMDs)transmission,namely Multi-AoI,with a well-designed cross-slot directed graph(CSG).With the proposed CSG,we make optimizations on the locations of cache nodes by solving a nonlinear integer programming problem on minimizing Multi-AoI.In particular,we put up forward three specific algorithms respectively for improving the Multi-AoI,i.e.,the minimum queuing delay algorithm(MQDA)based on node deviation from average level,the minimum propagation delay algorithm(MPDA)based on the node propagation delay reduction,and a delay balanced algorithm(DBA)based on node deviation from average level and propagation delay reduction.The simulation results show that the proposed mechanism can effectively improve the freshness of information compared with the random selection algorithm. 展开更多
关键词 age of information cached distribution satellite-integrated internet of things time-varying graph
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UAV-Assisted FSO Communication System with Amplify-and-Forward Protocol under AOA Fluctuations:A Performance Analysis
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作者 Maozhe Xu Guanjun Xu +3 位作者 Youran Dong Weizhi Wang Qinyu Zhang Zhaohui Song 《China Communications》 SCIE CSCD 2023年第11期111-130,共20页
Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim... Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance. 展开更多
关键词 amplify-and-forward protocol angle-ofarrival fluctuations FSO communication Malaga distribution UAV relay
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UWB channel modeling for indoor line-of-sight environment 被引量:5
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作者 汪洋 许洪光 +1 位作者 张钦宇 张乃通 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2007年第6期866-870,共5页
SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new stat... SV/IEEE 802.15.3a model has been the standard model for Ultra-wide bandwidth (UWB) indoor non-line-of-sight (NLOS) wireless propagation,but for line-of-sight (LOS) case,it is not well defined. In this paper,a new statistical distribution model exclusively used for LOS environment is proposed based on investigation of the experimental data. By reducing the number of the visible random arriving clusters,the model itself and the parameters estimating of the corresponding model are simplified in comparison with SV/IEEE 802.15.3a model. The simulation result indicates that the proposed model is more accurate in modeling small-scale LOS environment than SV/IEEE 802.15.3a model when considering cumulative distribution functions (CDFs) for the three key channel impulse response (CIR) statistics. 展开更多
关键词 UWB LINE-OF-SIGHT indoor propagation channel MULTIPATH statistical model
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Joint Power-Trajectory-Scheduling Optimization in A Mobile UAV-Enabled Network via Alternating Iteration 被引量:4
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作者 Xiaohan Qi Minxin Yuan +1 位作者 Qinyu Zhang Zhihua Yang 《China Communications》 SCIE CSCD 2022年第1期136-152,共17页
This work focuses on an unmanned aerial vehicle(UAV)-enabled mobile edge computing(MEC) system based on device-to-device(D2D) communication. In this system, the UAV exhibits caching,computing and relaying capabilities... This work focuses on an unmanned aerial vehicle(UAV)-enabled mobile edge computing(MEC) system based on device-to-device(D2D) communication. In this system, the UAV exhibits caching,computing and relaying capabilities to periodically provide specific service to cellular users and D2D receiver nodes in the appointed time slot. Besides, the D2D transmitter can provide additional caching services to D2D receiver to reduce the pressure of the UAV. Note that communication between multi-type nodes is mutually restricted and different links share spectrum resources. To achieve an improved balance between different types of node, we aim to maximize the overall energy efficiency while satisfying the quality-of-service requirements of the cellular nodes.To address this problem, we propose an alternating iteration algorithm to jointly optimize the scheduling strategies of the user, transmitting power of the UAV and D2D-TX nodes, and UAV trajectory. The successive convex approximation, penalty function, and Dinkelbach method are employed to transform the original problem into a group of solvable subproblems and the convergence of the method is proved. Simulation results show that the proposed scheme performs better than other benchmark algorithms, particularly in terms of balancing the tradeoff between minimizing UAV energy consumption and maximizing throughput. 展开更多
关键词 UAV MEC network D2D joint optimization energy efficiency
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Deterministic simulation of UWB indoor propagation channel 被引量:2
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作者 Wang Yang Zhang Naitong +1 位作者 Zhang Qinyu Zhang Zhongzhao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第3期447-452,共6页
A site-specific model of UWB pulse propagation in indoor environment is addressed. The simulation utilizes the principles of geometrical optics (GO) for direct and reflected paths' tracing and the time domain techn... A site-specific model of UWB pulse propagation in indoor environment is addressed. The simulation utilizes the principles of geometrical optics (GO) for direct and reflected paths' tracing and the time domain technique for describing the transient electromagnetic field reflected from wall, floor, ceiling, and objects. The polarization of the received waveform is determined by taking into account the radiation pattern of the transmitting and receiving antennas, as well as the polarization changes owing to every reflection. The model provides more intrinsical interpretations for UWB pulse propagation in realistic indoor environment. 展开更多
关键词 UWB time domain indoor propagation channel diffraction.
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Semisupervised Encrypted Traffic Identification Based on Auxiliary Classification Generative Adversarial Network 被引量:2
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作者 Jiaming Mao Mingming Zhang +5 位作者 Mu Chen Lu Chen Fei Xia Lei Fan ZiXuan Wang Wenbing Zhao 《Computer Systems Science & Engineering》 SCIE EI 2021年第12期373-390,共18页
The rapidly increasing popularity of mobile devices has changed the methods with which people access various network services and increased net-work traffic markedly.Over the past few decades,network traffic identific... The rapidly increasing popularity of mobile devices has changed the methods with which people access various network services and increased net-work traffic markedly.Over the past few decades,network traffic identification has been a research hotspot in the field of network management and security mon-itoring.However,as more network services use encryption technology,network traffic identification faces many challenges.Although classic machine learning methods can solve many problems that cannot be solved by port-and payload-based methods,manually extract features that are frequently updated is time-consuming and labor-intensive.Deep learning has good automatic feature learning capabilities and is an ideal method for network traffic identification,particularly encrypted traffic identification;Existing recognition methods based on deep learning primarily use supervised learning methods and rely on many labeled samples.However,in real scenarios,labeled samples are often difficult to obtain.This paper adjusts the structure of the auxiliary classification generation adversarial network(ACGAN)so that it can use unlabeled samples for training,and use the wasserstein distance instead of the original cross entropy as the loss function to achieve semisupervised learning.Experimental results show that the identification accuracy of ISCX and USTC data sets using the proposed method yields markedly better performance when the number of labeled samples is small compared to that of convolutional neural network(CNN)based classifier. 展开更多
关键词 Encrypted traffic recognition deep learning generative adversarial network traffic classification semisupervised learning
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A ground reflection model for I-UWB signal propagation
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作者 汪洋 张钦宇 +2 位作者 张乃通 刘法 张继良 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第1期23-26,共4页
Impulse systems do not undergo the multi-path destructive interference that manifests itself as Rayleigh fading prevalent in continuous wave systems, but rather show up as delayed replications of the direct impulse. I... Impulse systems do not undergo the multi-path destructive interference that manifests itself as Rayleigh fading prevalent in continuous wave systems, but rather show up as delayed replications of the direct impulse. In this paper, the model for impulse signals propagation over a plane earth is proposed. The condition for direct pulse and its replication overlapping each other was investigated. The model described here also takes into account the polarization of the transmission signals and the reflection coefficient of the plane, which was always neglected by previous approaches. The simulation result shows that the path loss can be characterized as 3 zones with different path loss exponents as the distance between transmitter and receiver (T-R) increasing. 展开更多
关键词 UWB path loss 2-ray model muhipath
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Sub-terahertz transmissive reconfigurable intelligent surface for integrated beam steering and self-OOK-modulation 被引量:2
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作者 Dongfang Shen Feng Lan +13 位作者 Luyang Wang Tianyang Song Munan Yang Tianyu Hu Yueting Li Xiaolei Nie Jiayao Yang Shixiong Liang Hongxin Zeng Hui-Fang Zhang Pinaki Mazumder Ziqiang Yang Yaxin Zhang Tie Jun Cui 《Light(Science & Applications)》 2025年第1期131-141,共11页
Boasting superior flexibility in beam manipulation and a simpler framework than traditional phased arrays,terahertz metasurface-based phased arrays show great promise for 5G-A/6G communication networks.Compared with t... Boasting superior flexibility in beam manipulation and a simpler framework than traditional phased arrays,terahertz metasurface-based phased arrays show great promise for 5G-A/6G communication networks.Compared with the reflective reconfigurable intelligent surface(reflective RIS),the transmissive RIS(TRIS)offers more feasibility for transceiver multiplexing systems to meet the growing demand for high-performance beam tracking in terahertz communication and radar systems.However,the terahertz TRIS encounters greater challenges in phase shift,beam efficiency,and complex circuitry.Here,we propose a sub-terahertz TRIS based on the phase shift via Pancharatnam-Berry(PB)metasurface and self-on-off keying(OOK)modulation via Schottky diodes.The electrically reconfigurable unit cell consists of a column-wise phase resonator and a rectangular slot.An experimental retrieved equivalent lumped-element circuit model is implemented in joint field-circuit simulations and is validated by experiments.A fabricated prototype demonstrates excellent performance of TRIS with the minimum insertion loss of 2.8 dB for operational states,large bandwidth nearly covering the entire W-band for 1-bit phase shift,deep OOK amplitude modulation of 12 dB,and wide scanning range of±60°with low specular transmission.We further implement an integrated platform combining high-speed beam steering and spatial-light modulation,verifying the point-to-point signal transmissions in different directions using the TRIS platform.The proposed TRIS with high-performance and cost-effective fabrication makes it a promising solution to terahertz minimalist communication systems,radar,and satellite communication systems. 展开更多
关键词 RECONFIGURABLE REFLECTIVE RESONATOR
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How to apply polar codes in high throughput space communications 被引量:1
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作者 FENG BoWen JIAO Jian +1 位作者 WU ShaoHua ZHANG QinYu 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第8期1371-1382,共12页
This paper describes how to apply polar codes in high-throughput space communications.The high throughput space communications can enable terabit data rate capacity wideband wireless transmissions,and offer service av... This paper describes how to apply polar codes in high-throughput space communications.The high throughput space communications can enable terabit data rate capacity wideband wireless transmissions,and offer service availability of anywhere and anytime.The paper investigates the channel characteristics in space communications.The channels are lossy,time-varying,intermittent,long-latency,and with imperfect channel state information(CSI).In order to make the polar codes suitable for the space channel,some improvements and designs on the polar codes are provided in this paper.The encoding and decoding methods of polar codes are discussed,which are the key to determine the performance.We describe some rateless polar coding schemes that can guide the construction of suitable codes for time-varying channels with no-CSI in long-haul transmissions.Then,a high-rate parallel concatenation scheme of polar codes is introduced,which can improve the anti-interrupt ability of polar codes.Moreover,in order to support the massive connectivity requirements of future space communication networks,polar-coded sparse-code-multiple-access(SCMA)schemes are investigated. 展开更多
关键词 space communications polar code concatenated coding high throughput
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Real-time programmable metasurface for terahertz multifunctional wave front engineering 被引量:8
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作者 Feng Lan Luyang Wang +7 位作者 Hongxin Zeng Shixiong Liang Tianyang Song Wenxin Liu Pinaki Mazumder Ziqiang Yang Yaxin Zhang Daniel M.Mittleman 《Light(Science & Applications)》 SCIE EI CSCD 2023年第9期1795-1806,共12页
Terahertz(THz)technologies have become a focus of research in recent years due to their prominent role in envisioned future communication and sensing systems.One of the key challenges facing the field is the need for ... Terahertz(THz)technologies have become a focus of research in recent years due to their prominent role in envisioned future communication and sensing systems.One of the key challenges facing the field is the need for tools to enable agile engineering of THz wave fronts.Here,we describe a reconfigurable metasurface based on GaN technology with an array-of-subarrays architecture.This subwavelength-spaced array,under the control of a 1-bit digital coding sequence,can switch between an enormous range of possible configurations,providing facile access to nearly arbitrary wave front control for signals near 0.34 THz.We demonstrate wide-angle beam scanning with 1°of angular precision over 70 GHz of bandwidth,as well as the generation of multi-beam and diffuse wave fronts,with a switching speed up to 100 MHz.This device,offering the ability to rapidly reconfigure a propagating wave front for beam-forming or diffusively scattered wide-angle coverage of a scene,will open new realms of possibilities in sensing,imaging,and networking. 展开更多
关键词 WAVE SCATTERED ARBITRARY
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Energy-Theft Detection Issues for Advanced Metering Infrastructure in Smart Grid 被引量:24
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作者 Rong Jiang Rongxing Lu +3 位作者 Ye Wang Jun Luo Changxiang Shen Xuemin(Sherman) Shen 《Tsinghua Science and Technology》 SCIE EI CAS 2014年第2期105-120,共16页
With the proliferation of smart grid research, the Advanced Metering Infrastructure (AMI) has become the first ubiquitous and fixed computing platform. However, due to the unique characteristics of AMI, such as comp... With the proliferation of smart grid research, the Advanced Metering Infrastructure (AMI) has become the first ubiquitous and fixed computing platform. However, due to the unique characteristics of AMI, such as complex network structure, resource-constrained smart meter, and privacy-sensitive data, it is an especially challenging issue to make AMI secure. Energy theft is one of the most important concerns related to the smart grid implementation. It is estimated that utility companies lose more than S25 billion every year due to energy theft around the world. To address this challenge, in this paper, we discuss the background of AMI and identify major security requirements that AMI should meet. Specifically, an attack tree based threat model is first presented to illustrate the energy-theft behaviors in AMI. Then, we summarize the current AMI energy-theft detection schemes into three categories, i.e., classification-based, state estimation-based, and game theory-based ones, and make extensive comparisons and discussions on them. In order to provide a deep understanding of security vulnerabilities and solutions in AMI and shed light on future research directions, we also explore some open challenges and potential solutions for energy-theft detection. 展开更多
关键词 smart grid Advanced Metering Infrastructure (AMI) SECURITY energy-theft detection
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An analysis in metal barcode label design for reference
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作者 Yin ZHAO Hong-guang XU Qin-yu ZHANG 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2016年第2期173-184,共12页
We employ nondestructive evaluation involving AC field measurement in detecting and identifying metal barcode labels,providing a reference for design.Using the magnetic scalar potential boundary condition at notches i... We employ nondestructive evaluation involving AC field measurement in detecting and identifying metal barcode labels,providing a reference for design.Using the magnetic scalar potential boundary condition at notches in thin-skin field theory and 2D Fourier transform,we introduce an analytical model for the magnetic scalar potential induced by the interaction of a high-frequency inducer with a metal barcode label containing multiple narrow saw-cut notches,and then calculate the magnetic field in the free space above the metal barcode label.With the simulations of the magnetic field,qualitative analysis is given for the effects on detecting and identifying metal barcode labels,which are caused by metal material,notch characteristics,exciting inducer properties,and other factors that can be used in metal barcode label design as reference.Simulation results are in good accordance with experiment results. 展开更多
关键词 Metal barcode label Signal detection AC field measurement Internet of things
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