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A Correlation-Based Stochastic Model for Massive MIMO Channel

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China Communications 2024年第1期21卷 175-187页

作者： Yang Liu Gang Li Chengxiang Wang national mobile Communications Research laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 211189China School of Internet of Things engineering Jiangnan UniversityWuxi 214122China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China

In this paper,the channel impulse response matrix(CIRM)can be expressed as a sum of couplings between the steering vectors at the base station(BS)and the eigenbases at the mobile station(MS).Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the eigenbases.Extensive measurements were carried out to evaluate the performance of this proposed model.Furthermore,the physical implications of this model were illustrated and the capacities are analyzed.In addition,the azimuthal power spectrum(APS)of several models was analyzed.Finally,the channel hardening effect was simulated and discussed.Results showed that the proposed model provides a better fit to the measured results than the other CBSM,i.e.,Weichselberger model.Moreover,the proposed model can provide better tradeoff between accuracy and complexity in channel synthesis.This CIRM model can be used for massive MIMO design in the future communication system design.

关键词： CBSM channel capacity channel hardening channel modeling massive MIMO

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Gradient sparsification for efficient wireless federated learning with differential privacy

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Science China(Information Sciences) 2024年第4期67卷 272-288页

作者： Kang WEI Jun LI Chuan MA Ming DING Feng SHU Haitao ZHAO Wen CHEN Hongbo ZHU School of Electronic and Optical engineering Nanjing University of Science and Technology Zhejiang lab Key laboratory of Computer network and Information Integration(Southeast University) Ministry of Education Data61 Commonwealth Scientific and Industrial Research Organisation School of Information and Communication engineering Hainan University School of Communications and Information engineering Nanjing University of Posts and Telecommunications School of Electronic Information and Electrical engineering Shanghai Jiao Tong University

Federated learning(FL) enables distributed clients to collaboratively train a machine learning model without sharing raw data with each other. However, it suffers from the leakage of private information from uploading models. In addition, as the model size grows, the training latency increases due to the limited transmission bandwidth and model performance degradation while using differential privacy(DP)protection. In this paper, we propose a gradient sparsification empowered FL framework with DP over wireless channels, to improve training efficiency without sacrificing convergence performance. Specifically, we first design a random sparsification algorithm to retain a fraction of the gradient elements in each client’s local model, thereby mitigating the performance degradation induced by DP and reducing the number of transmission parameters over wireless channels. Then, we analyze the convergence bound of the proposed algorithm, by modeling a non-convex FL problem. Next, we formulate a time-sequential stochastic optimization problem for minimizing the developed convergence bound, under the constraints of transmit power, the average transmitting delay, as well as the client’s DP requirement. Utilizing the Lyapunov drift-plus-penalty framework, we develop an analytical solution to the optimization problem. Extensive experiments have been implemented on three real-life datasets to demonstrate the effectiveness of our proposed algorithm. We show that our proposed algorithms can fully exploit the interworking between communication and computation to outperform the baselines, i.e., random scheduling, round robin, and delay-minimization algorithms.

关键词： federated learning differential privacy gradient sparsification Lyapunov drift convergence analysis

Wideband chaos generation using a VCSEL with intensity modulation optical injection for random number generation

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Science China(Information Sciences) 2024年第6期67卷 457-458页

作者： Yu HUANG Shuangquan GU Yuhang FENG Yigong YANG Shuiying XIANG Pei ZHOU Nianqiang LI School of Optoelectronic Science and engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University State Key laboratory of Integrated Service networks Xidian University Key lab of Advanced Optical Manufacturing technologies of Jiangsu Province & Key lab of Modern Optical technologies of Education Ministry of China Soochow University

Physical random numbers have been widely used in modern network society,such as the generation of cryptographic keys for classical and quantum cryptography systems[1].Among the many sources of physical entropy,chaotic semiconductor lasers have attracted wide attention due to their desired characteristics including larger bandwidth,low cost,and monolithic integration[2].

关键词： Optical signal processing

Robust textile-based spoof plasmonic frequency scanning antenna for on-body IoT applications

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Science China(Information Sciences) 2024年

作者： Zhao-Min CHEN Jun-Lin ZHAN Hao CHEN Ya LI Hong-Jun HE Wu YANG Zhen-Guo LIU Wei-Bing LU State Key lab of Millimeter Waves School of Information Science and EngineeringSoutheast University Center for Flexible RF Technology Frontiers Science Center for Mobile Information Communication and SecuritySoutheast University Future Research laboratory China Mobile Research Institute Purple Mountain laboratories

Securing a comfortable, wearable compact frequency beam scanning antenna(FBSA) with robustness to deformation, low specific absorption rate(SAR), and good coverage of the surrounding environment for Internet of Things(Io T) applications, such as on-body navigation and wireless communication is an emerging challenge. In this work, a robust textile-based spoof plasmonic frequency scanning antenna utilizing higher-order modes is presented, which is also robust to deformation caused by the activities of the human body. The innovative design of the element ensures the high-efficiency transmission of the fundamental mode of spoof surface plasmon polaritons(SSPP) structure, providing the potential of being a multifunctional composite device in the compact on-body network. Besides, an artificial magnetic conductor(AMC) is designed underneath the SSPP structure, obtaining a low SAR value(0.113 W/kg), which ensures the safety of users. As a practical realization of this concept, a textile-based spoof plasmonic antenna was fabricated in the microwave regime and the performed experimental results show the proposed antenna has a single-beam radiation characteristic with a 70°beam scanning angle range when the frequency is 4.7–6.0 GHz with a high average realized gain of 13.15 dBi. And it still maintains a steady performance when faced with structure deformation, which proves its robustness. Wireless communication quality experiments are performed to demonstrate the proposed antenna can measure the angles of targets and realize wireless signal transmission to specific targets as the frequency varies, it may find great potential in the field of on-body Io T applications.

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Coordination of networking and computing: toward new information infrastructure and new services mode

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Frontiers of Information Technology & Electronic engineering 2024年第5期25卷 629-632页

作者： Xiaoyun WANG Tao SUN Yong CUI Rajkumar BUYYA Deke GUO Qun HUANG Hassnaa MOUSTAFA Chen TIAN Shangguang WANG China mobile Communications Corporation Beijing 100032China China mobile Research Institute Beijing 100053China Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China CLOUDS lab School of Computing and Information SystemsUniversity of MelbourneMelbourneVIC 3010Australia national Key laboratory of Information Systems engineering National University of Defense TechnologyChangsha 410073China School of Computer Science Peking UniversityBeijing 100871China Intel Corporation Santa ClaraCA 95054USA State Key laboratory for Novel Sofiware Technology Nanjing UniversityNanjing 210023China State Key laboratory of networking and Switching Technology Bejing University of Posts and TelecommunicationsBeijing 100876China

Computing,serving as the cornerstone of information processing,plays a pivotal role in the digital service era.The"network"and"computing,"responsible for information transmission and processing respectively,traditionally belong to different stakeholders and have evolved separately.However,the recent trend toward the coordination and integration of computing and networks has garnered significant attention from both industry and academia.Concepts such as"computility network"and"computing force network"have emerged,and the International Telecommunication Union-Telecommunication Standardization(ITU-T)has initiated efforts to develop standards for the coordination of networking and computing(CNC),focusing on the architecture and framework.

关键词： computing services network

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Mining KPI correlations for non-parametric anomaly diagnosis in wireless networks

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Science China(Information Sciences) 2023年第6期66卷 155-169页

作者： Tengfei SUI Xiaofeng TAO Huici WU Xuefei ZHANG Jin XU Guoshun NAN national engineering laboratory for mobile network technologies Beijing University of Posts and Telecommunications

The increase in mobile data traffic has imposed unprecedented pressure on wireless network management. KPI-based anomaly diagnosis can alleviate such pressure by automatically identifying the cause of abnormalities in the traffic and providing end-to-end monitoring and optimization. Previous approaches mainly focus on finding a subset of anomaly-inducing KPIs on the basis of supervised learning procedures.These studies have two possible limitations:(1)the inherent correlations between KPIs that are proven to be effective for the anomaly diagnosis, are still largely underexplored;(2)machine learning models heavily rely on human annotations, which are expensive and labor-intensive. Therefore, we propose random matrix theorybased KPI identification(RKI), a novel method that automatically mines rich interactions between KPIs for anomaly diagnosis without using any learnable parameters or human annotations. Specifically, RKI diagnoses the abnormal KPIs in two steps. First, we build a matrix for anomaly KPI detection to mine the spectrum of its covariances. Second, another new matrix is reconstructed to calculate the correlation difference. By doing so, the anomaly KPIs that have larger correlation difference scores can be efficiently identified in the wireless traffic without any trainable parameters. In extensive experiments on a public dataset, RKI yields a 6.5%higher true diagnostic rate and 11.36% lower false alarming rate than the statistical model, demonstrating its effectiveness. A 100× larger scale synthetic dataset also demonstrates the capabilities of RKI to explore massive data traffic under real-word scenarios. Finally, we discuss RKI’s potential applications of our method in future 6G wireless networks.

关键词： random matrix theory spectral distribution anomaly diagnosis data analysis wireless networks

Physical layer authentication in UAV-enabled relay networks based on manifold learning

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Science China(Information Sciences) 2022年第12期65卷 263-283页

作者： Shida XIA Xiaofeng TAO Na LI Shiji WANG Jin XU national engineering lab for mobile network technologies Beijing University of Posts and Telecommunications Beijing University of Posts and Telecommunications Research Institute

An unmanned aerial vehicle(UAV) relay network is a promising solution in the next-generation wireless networks due to its high capacity and unlimited geography. However, because of the openness of wireless channels and UAV mobility, it is remarkably challenging to guarantee the secure access of UAV relay. In this paper, we investigate the physical layer authentication(PLA) to verify the identity of the UAV relay for preventing unauthorized access to users’ information or network service. Unlike most existing PLA methods for UAV, the proposed PLA scheme fully considers the time-varying of physical layer attributes caused by UAV mobility, and transforms the authentication problem into recognizing nonlinearly separable physical layer data. Particularly, we propose a manifold learning-based PLA scheme that can authenticate the mobile UAV relay in real time by establishing the local correlation of physical layer attributes. The Markov chain of physical layer data in the time domain is established to evaluate UAV state transition probability through the proposed diffusion map algorithm. The legitimate UAV and spoofing attackers can always be authenticated by the different motion states. Performance analysis offered a comprehensive understanding of the proposed scheme. Extensive simulations confirm that the performance of the proposed scheme improves over 18% in resisting the intelligent spoofing UAV compared with the traditional methods.

关键词： UAV relay physical layer authentication mobility manifold learning diffusion map state transition probability

Blockchain-based vehicular edge computing networks: the communication perspective

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Science China(Information Sciences) 2023年第7期66卷 253-265页

作者： Lin HE Fuchang LI Haikun XU Wenbo XIA Xuefei ZHANG Xiaofeng TAO Research Institute China United Network Communications Corporation Limited national engineering Research Center of mobile network technologies Beijing University of Posts and Telecommunications

Vehicular edge computing(VEC) networks can satisfy the increasing demands of data processing by offloading the computation tasks to multiple distributed edge computing nodes assisted by servers. These edge servers generally combine with roadside units(RSUs). However, RSUs with edge servers cannot be fully trusted, possibly leading to serious security and privacy problems. Combining blockchain with VEC networks may establish a trusted and decentralized vehicular environment, but the coexistence of multiple communication modes comprising vehicle-to-vehicle(V2V), vehicle-to-RSU(V2R), and RSU-to-RSU(R2R) makes the block propagation patterns have different effects on the block consensus process. In this paper, we study the block propagation patterns between vehicles and RSUs with edge servers under three communication modes.We first give the closed-form expressions for the single-block and multiblock propagation times in two specific conditions to explore how the priority of a block generated from a specific node affects the block propagation process, in which multiblock propagation embodies competitive propagation due to blockchain forking.Then, an innovative consensus mechanism that fully invokes the communication capability of the nodes is proposed, and the block propagation time and frequency can be substantially reduced under this mechanism.In addition, an important finding is that under the conventional and proposed consensus mechanisms, an RSU or a vehicle that creates a new block plays a decisive role in the block propagation pattern.

关键词： block propagation blockchain consensus VEC network

Secret key generation over a Nakagami-m fading channel with correlated eavesdropping channel

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Science China(Information Sciences) 2022年第9期65卷 273-285页

作者： Shixun GONG Xiaofeng TAO Na LI Haowei WANG Jin XU national engineering laboratory for mobile network technologies Beijing University of Posts and Telecommunications Beijing University of Posts and Telecommunications Research Institute

The analysis of secret key capacity is an important investigation on the design of secret key agreement protocol. In this paper, we characterize the secret key capacity based on received signal envelopes obeying Nakagami-m distribution between two legitimate users, in the presence of a passive eavesdropper,when the eavesdropping channel is correlated with the legitimate channel. The expression of secret key capacity is derived based on mutual information and applies to both integer and non-integer m. Simulation results indicate that the secret key capacity is proportional to m-fading parameter and average signal-tonoise ratio(SNR) and inversely proportional to the number of paths. In addition, some behaviors of secret key capacity over a high mobility fading channel, and microcell and macrocell environments are provided.These results cover the performance of secret key capacity when the received signal envelope follows Rayleigh,Rician, and Gaussian distributions.

关键词： physical layer security physical layer secret key generation Nakagami-$m$ fading correlated eavesdropping channel secret key capacity