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High contrast linking six lasers to a 1 GHz Yb:fiber laser frequency comb

Chinese Optics Letters 2019年第4期17卷 62-65页

作者： Yuxuan Ma Fei Meng Yan Wang Aimin Wang Zhigang Zhang State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University National Institute of Metrology

We demonstrate a 0.95 GHz repetition rate fully stabilized Yb:fiber frequency comb without optical amplification. Benefitting from the high mode power and high coherence, this comb achieved 35 to 42 dB signal to noise ratio on the direct heterodyne beat signals with at least six continuous wave lasers(at 580, 679, 698, 707, 813, and922 nm) while keeping >40 dB carrier envelope frequency signal. It can be used for the direct measurement of optical frequencies at visible and near-infrared wavelengths and has great potential on simultaneous comparison of multiple optical frequencies.

关键词： 0.95 GHz power and high coherence optical frequencies

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Fluid Antennas-Enabled Multiuser Uplink: A Low-Complexity Gradient Descent for Total Transmit Power Minimization

arXiv

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arXiv 2023年

作者： Hu, Guojie Wu, Qingqing Xu, Kui Ouyang, Jian Si, Jiangbo Cai, Yunlong Al-Dhahir, Naofal The College of Communication Engineering Rocket Force University of Engineering Xi’an710025 China The Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China The College of Communications Engineering The Army of Engineering University Nanjing210007 China The Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China The Integrated Service Networks Lab of Xidian University Xi’an710100 China The College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China The Department of Electrical and Computer Engineering The University of Texas at Dallas RichardsonTX75080 United States

We investigate multiuser uplink communications from multiple single-antenna users to a base station (BS), which is equipped with multiple fluid antennas (FAs) and adopts zero-forcing receivers to decode multiple signals. We aim to optimize antennas’ positions at the BS, to minimize the total transmit power of all users subject to the minimum rate requirement. After applying transformations, we show that the problem is equivalent to minimizing the sum of each eigenvalue’s reciprocal of a matrix, which is a function of all antennas’ positions at the BS. Subsequently, the projected gradient descent (PGD) method is utilized to find a locally optimal solution. In particular, different from the latest related work, we exploit the eigenvalue decomposition to successfully derive a closed-form gradient for the PGD, which facilitates the practical implementation greatly. We demonstrate by simulations that via careful optimization for all antennas’ positions in our proposed design, the total transmit power of all users can be decreased significantly as compared to competitive benchmarks. Copyright © 2023, The Authors. All rights reserved.

关键词： Antennas

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A controllable coupling structure for silicon microring resonators based on adiabatic elimination

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Chinese Optics Letters 2020年第1期18卷 110-114页

作者： Fenghe Yang Pengfei Sun Ruixuan Chen Zhiping Zhou State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871China Peking University Shenzhen Research Institute Shenzhen 518057China Nano-optoelectronics Frontier Center of Ministry of Education Peking UniversityBeijing 100871China

Optical microring resonators are extensively employed in a wide range of physical studies and applications due to the resonance enhancement *** coupling control of a microring resonator is necessary in many scenarios,but modifications are essentially added to the resonator and impair the capability of optical ***,we propose a flexible coupling structure based on adiabatic elimination that allows low-loss active coupling control without any modifications to the *** self-coupling coefficient can be monotonically or non-monotonically controllable by the proposed coupler,potentially at a high *** characteristic of the coupler when implemented in silicon microring resonators is investigated in detail using substantiated analytical theory and *** work provides a general method in coupling control while ensuring the resonance enhancement property,making active coupling control in a resonator-waveguide system feasible.

关键词： silicon photonics adiabatic elimination resonance system

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Massive MIMO

Massive MIMO

引用

IEEE Future networks World Forum (FNWF)

作者： Haijian Sun Chris Ng Yiming Huo Rose Qingyang Hu Ning Wang Chi-Ming Chen Kasturi Vasudevan Jin Yang Webert Montlouis Dauda Ayanda Kumar Vijay Mishra Kürşat Tekbiyik Nasir Hussain Harish Kumar Sahoo Yang Miao Boya Di Hongliang Zhang Özlem Tugfe Demir Department of Computer Science University of Wisconsin Whitewater IEEE Future Networks Massive MIMO Working Group University of Victoria Utah State University Zhengzhou University AT&T IEEE IIT KANPUR Verizon Communications Inc. Johns Hopkins University University of KwaZulu-Natal South Africa United States CCDC Army Research Laboratory Department of Electronics and Communication Engineering Istanbul Technical University Samsung Electronics America Veer Surendra Sai University of Technology India University of Twente The Netherlands Peking University TOBB University of Economics and Technology

The use of a large number of antenna elements, known as Massive MIMO, is seen as a key enabling technology in the 5G and Beyond wireless ecosystem. The intelligent use of a multitude of antenna elements unleashes unprecedented flexibility and control on the physical channel of the wireless medium. Through Massive MIMO and other techniques, it is envisioned that the 5G and beyond wireless system will be able to support high throughput, high reliability (low bit-error-rate (BER)), high energy efficiency, low latency, and an internet-scale number of connected devices. Massive MIMO and related technologies will be deployed in the mid-band (sub 6 GHz) for coverage, all the way to mmWave bands to support large channel bandwidths. It is envisioned that Massive MIMO will be deployed in different environments: Frequency Division Duplex (FDD), (Time Division Duplex (TDD), indoor / outdoor, small cell, macro cell, and other heterogeneous networks (HetNet) configurations. Accurate and useful channel estimation remains a challenge in the efficient adoption of Massive MIMO techniques, and different performance-complexity tradeoffs may be supported by different Massive MIMO architectures such as digital, analog, and/or digital/analog hybrid. Carrier frequency offset (CFO), which arises due to the relative motion between the transmitter and receiver, is another important topic. Recently, maximum likelihood (ML) methods of CFO estimation have been proposed, that achieve very low root mean square (RMS) estimation errors, with a large scope for parallel processing and well suited for application with turbo codes. Massive MIMO opens up a whole new dimension of parameters where the wireless applications or other network layers may control or influence the operation and performance of the physical wireless channel. To fully reap the benefits of such flexibility, the latest advances in artificial intelligence (AI) and machine learning (ML) techniques will be leveraged to monitor and optim

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Low-loss hybrid plasmonic TM-pass polarizer using polarization-dependent mode conversion

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Photonics Research 2020年第7期8卷 1197-1202页

作者： Ruixuan Chen Bowen Bai Zhiping Zhou State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsSchool of Electronics Engineering and Computer SciencePeking UniversityBeijing 100871China Peking University Shenzhen Research Institute Shenzhen 518057China Nano-optoelectronics Frontier Center of Ministry of Education Peking UniversityBeijing 100871China

A low-loss hybrid plasmonic transverse magnetic(TM)-pass polarizer has been demonstrated utilizing polarization-dependent mode *** advantage of the silicon hybrid plasmonic slot waveguide(HPSW),the unwanted transverse electric(TE)fundamental mode can be efficiently converted first to a TM higher-order mode and then suppressed by a power combiner,while the retained TM fundamental mode can pass through with negligible *** the HPSW feature both strong structural asymmetry and a small interaction area in the cross-section between the metal and optical field,the optimized insertion loss of the device is as low as 0.4 d *** the wavelength of 1550 nm,the extinction ratio is 28.3 d B with a moderate footprint of 2.38μm×10μ*** the entire C band,the average reflection of the TE mode is suppressed below-14 d B,and the extinction ratio is over 18.6 d *** work provides another more efficient and effective approach for better on-chip polarizers.

关键词： polarization polarizer pass

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Joint optimization of UAV aided covert edge computing via a deep reinforcement learning framework

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Chinese Journal of Aeronautics 2024年

作者： Wei WEI Shu FU Yujie TANG Yuan WU Haijun ZHANG College of Microelectronics and Communication Engineering Chongqing University Chongqing 400044 China Department of Faculty of Computer Science Dalhousie University Halifax NS B3H 4R2 Canada State Key Laboratory of Internet of Things for Smart City and the Department of Computer and Information Science University of Macau Macau Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing Beijing 100083 China

In this work, we consider an Unmanned Aerial Vehicle (UAV) aided covert edge computing architecture, where multiple sensors are scattered with a certain distance on the ground. The sensor can implement several computation tasks. In an emergency scenario, the computational capabilities of sensors are often limited, as seen in vehicular networks or Internet of Things (IoT) networks. The UAV can be utilized to undertake parts of the computation tasks, i.e. , edge computing. While various studies have advanced the performance of UAV-based edge computing systems, the security of wireless transmission in future 6G networks is becoming increasingly crucial due to its inherent broadcast nature, yet it has not received adequate attention. In this paper, we improve the covert performance in a UAV aided edge computing system. Parts of the computation tasks of multiple ground sensors are offloaded to the UAV, where the sensors offload the computing tasks to the UAV, and Willie around detects the transmissions. The transmit power of sensors, the offloading proportions of sensors and the hovering height of the UAV affect the system covert performance, we propose a deep reinforcement learning framework to jointly optimize them. The proposed algorithm minimizes the system average task processing delay while guaranteeing that the transmissions of sensors are not detected by the Willie under the covertness constraint. Extensive simulations are conducted to verify the effectiveness of the proposed algorithm to decrease the average task processing delay with comparison with other algorithms.

关键词： Covert communication Unmanned aerial vehicle Edge computing Joint optimization Deep reinforcement

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A Novel Shilling Attack Detection Model Based on Particle Filter and Gravitation

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China communications 2019年第10期16卷 112-132页

作者： Lingtao Qi Haiping Huang Feng Li Reza Malekian Ruchuan Wang College of Computer Nanjing University of Posts and TelecommunicationsNanjing 210003China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Nanjing 210003China “Broadband Wireless Communication and Sensor Network Technology”Key Lab of Ministry of Education NUPTNanjing 210003China College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Computer Science and Media Technology Malmo UniversityMalmo 20506Sweden

With the rapid development of e-commerce, the security issues of collaborative filtering recommender systems have been widely investigated. Malicious users can benefit from injecting a great quantities of fake profiles into recommender systems to manipulate recommendation results. As one of the most important attack methods in recommender systems, the shilling attack has been paid considerable attention, especially to its model and the way to detect it. Among them, the loose version of Group Shilling Attack Generation Algorithm (GSAGenl) has outstanding performance. It can be immune to some PCC (Pearson Correlation Coefficient)-based detectors due to the nature of anti-Pearson correlation. In order to overcome the vulnerabilities caused by GSAGenl, a gravitation-based detection model (GBDM) is presented, integrated with a sophisticated gravitational detector and a decider. And meanwhile two new basic attributes and a particle filter algorithm are used for tracking prediction. And then, whether an attack occurs can be judged according to the law of universal gravitation in decision-making. The detection performances of GBDM, HHT-SVM, UnRAP, AP-UnRAP Semi-SAD,SVM-TIA and PCA-P are compared and evaluated. And simulation results show the effectiveness and availability of GBDM.

关键词： shilling attack detection model collaborative filtering recommender systems gravitation-based detection model particle filter algorithm

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Joint Scheduling, Computing, and Load Balancing for Time Sensitive Traffic in SDN-Enabled Space-Air-Ground Integrated 6 G networks: A Federated Reinforcement Learning Approach

引用

IEEE Transactions on Mobile Computing 2025年

作者： Sun, Haitong Zhang, Haijun Ma, Hui Leung, Victor C.M Hebei Key Laboratory of Space-Air-Ground Intelligent Communication Beijing100083 China University of Science and Technology Beijing Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services Beijing100083 China Shenzhen University Department of Computer Science and Software Engineering Shenzhen518061 China University of British Columbia Department of Electrical and Computer Engineering VancouverBCV6T 1Z4 Canada

Low Earth Orbit (LEO) constellations and Unmanned Aerial Vehicle (UAV) networks enable wide coverage for the sixth generation (6G) mobile communication. However, it is a challenge to achieve high scheduling success rate, ultra-low latency, and efficient load balance in the Space-Air-Ground Integrated 6G Network (SAGGIN). This paper addresses the following issue: How to effectively and orderly transmit time-sensitive traffic in SAGGIN under strict deadlines, limited computational ability, and restrained link capacity? Specifically, this paper uses Software-Defined Networking (SDN) and designs a joint optimization method to enhance the traffic transmission ability of SAGGIN. Considering response time, computing cost, and link capacity in SAGGIN, the scheduling, computing, and load balance issues are modeled as a multi-objective optimization problem that minimizes the worst-case response time and computing cost of data frames while maximizing the network flow. Then, this paper leverages a Federated Reinforcement Learning (FRL) scheme to solve the problem. Results show that the FRL could achieve great scheduling, computing, and load balance performance. Specifically, our method can successfully schedule 80% of the traffic at most when the current network load is around 90%. Furthermore, the computational delay could reduce around 50%. © 2002-2012 IEEE.

关键词： Reinforcement learning

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TSGN: Transaction Subgraph networks Assisting Phishing Detection in Ethereum

arXiv

引用

arXiv 2022年

作者： Wang, Jinhuan Chen, Pengtao Xu, Xinyao Wu, Jiajing Shen, Meng Xuan, Qi Yang, Xiaoniu Institute of Cyberspace Security College of Information Engineering Zhejiang University of Technology Hangzhou310023 China School of Computer Science and Engineering Sun Yat-sen University Guangzhou510006 China School of Cyberspace Science and Technology Beijing Institute of Technology Beijing100081 China Shenzhen518066 China PCL Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen518000 China Utron Technology Company Ltd. Hangzhou310056 China Institute of Cyberspace Security Zhejiang University of Technology Hangzhou310023 China Science and Technology on Communication Information Security Control Laboratory Jiaxing314033 China

Due to the decentralized and public nature of the Blockchain ecosystem, the malicious activities on the Ethereum platform impose immeasurable losses for the users. Existing phishing scam detection methods mostly rely only on the analysis of original transaction networks, which is difficult to dig deeply into the transaction patterns hidden in the network structure of transaction interaction. In this paper, we propose a Transaction SubGraph Network (TSGN) based phishing accounts identification framework for Ethereum. We first extract transaction subgraphs for target accounts and then expand these subgraphs into corresponding TSGNs based on the different mapping mechanisms. In order to make our model incorporate more important information about real transactions, we encode the transaction attributes into the modeling process of TSGNs, yielding two variants of TSGN, i.e., Directed-TSGN and Temporal-TSGN, which can be applied to the different attributed networks. Especially, by introducing TSGN into multi-edge transaction networks, the Multiple-TSGN model proposed is able to preserve the temporal transaction flow information and capture the significant topological pattern of phishing scams, while reducing the time complexity of modeling large-scale networks. Extensive experimental results show that TSGN models can provide more potential information to improve the performance of phishing detection by incorporating graph representation learning. Copyright © 2022, The Authors. All rights reserved.

关键词： Topology

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A survey of state-of-the-art short text matching algorithms 4th

A survey of state-of-the-art short text matching algorithms

引用

4th International Conference on Data Mining and Big Data, DMBD 2019

作者： Hu, Weiwei Dang, Anhong Tan, Ying State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China and Department of Machine Intelligence School of Electronics Engineering and Computer Science Peking University Beijing100871 China

ISBN: (纸本)9789813295629

The short text matching task uses an NLP model to predict the semantic relevance of two texts. It has been used in many fields such as information retrieval, question answering and dialogue systems. This paper will review several state-of-the-art neural network based text matching algorithms in recent years. We aim to provide a quick start guide to beginners on short text matching. The representation based model DSSM is first introduced, which uses a neural network model to represent texts as feature vectors, and the cosine similarity between vectors is regarded as the matching score of texts. Word interaction based models such as DRMM, MatchPyramid and BERT are then introduced, which extract semantic matching features from the similarities of word pairs in two texts to capture more detailed interaction information between texts. We analyze the applicable scenes of each algorithm based on the effectiveness and time complexity, which will help beginners to choose appropriate models for their short text matching applications. © 2019, Springer Nature Singapore Pte Ltd.

关键词： Semantics

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