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Sub-Terahertz Channel Sounder: Review and Future Challenges

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China Communications 2023年第6期20卷 26-48页

作者： Yejian Lyu Pekka Kyosti Wei Fan Deparment of Electronic systems Aalborg UniversityAalborg Ost 9220Denmark center for wireless Communication-Radio Technology(CWC-RT) Oulu UniversityOulu 90570Finland Keysight Technologies Finland Oy Oulu 90630Finland

Due to the large amount of unused and unexplored spectrum resources, the so-called subTerahertz(sub-THz) frequency bands from 100 to 300 GHz are seen as promising bands for the next generation of wireless communication systems. Channel modeling at sub-THz bands is essential for the design and deployment of future wireless communication systems. Channel measurement is a widely adopted method to obtain channel characteristics and establish mathematical channel models. Channel measurements depend on the design and construction of channel sounders. Thus, reliable channel sounding techniques and accurate channel measurements are required. In this paper, the requirements of an ideal channel sounder are discussed and the main channel sounding techniques are described for the subTHz frequency bands. The state-of-the-art sub-THz channel sounders reported in the literature and respective channel measurements are presented. Moreover, a vector network analyzer(VNA) based channel sounder, which supports frequency bands from 220 to330 GHz is presented and its performance capability and limitation are evaluated. This paper also discussed the challenge and future outlook of the sub-THz channel sounders and measurements.

关键词： radio propagation beyond 5G communication sub-terahertz channel sounding techniques

A Resource Scheduling Scheme for Spectrum Aggregation in Cognitive Radio Based Heterogeneous Networks

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China Communications 2015年第9期12卷 100-111页

作者： Fu Yunhai Ma Lin Xu Yubin Harbin Institute of Technology Communication Research center Key Laboratory of Police wireless Digital Communication Ministry of Public Security

In spectrum aggregation(SA), two or more component carriers(CCs) of different bandwidths in different bands can be aggregated to support wider transmission bandwidth. The current resource scheduling schemes for spectrum aggregation are not optimal or suitable for CR based heterogeneous networks(Het Nets). Consequently, the authors propose a novel resource scheduling scheme for spectrum aggregation in CR based Het Nets, termed as cognitive radio based resource scheduling(CR-RS) scheme. CR-RS has a three-level structure. Under a dynamic traffic model, an equivalent throughput of the CCs based on the knowledge of primary users(PUs) is given. On this basis, the CR users data transmission time of each CC is equal in CR-RS. The simulation results show that CR-RS has the better performance than the current resource scheduling schemes in the CR based Het Nets. Meanwhile, CR-RS is also effective in other spectrum aggregation systems which are not CR based HetNets.

关键词： CR-RS spectrum aggregation resource scheduling cognitive radio heterogeneous networks

The Analysis on the Candidate Frequency Bands of Future Mobile Communication systems

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China Communications 2015年第S1期12卷 140-149页

作者： TAN Haifeng LI Wei WANG Tan FANG Jian FENG Zhiyong Key Laboratory of Universal wireless Communications Ministry of Education Beijing University of Posts and Telecommunications The State Radio Monitoring center(The State Radio Spectrum Management center)

Appropriate candidate frequency bands are extremely important for the development of future 5G systems. In this work, the researches on 5G spectrum around the world are summarized. Then the potential candidate frequency bands for 5G systems are investigated based on practical utilization of spectrum in China. For spectrum below 6GHz, the feasibility of possible frequency bands for 5G system are analyzed, which mainly come from 2G/3G/4G spectrum re-farming, the spectrum identified by footnotes for IMT systems in Regulations on the Radio Frequency Allocation of China, and potential candidate bands from WRC-15 Agenda Item 1.1. Moreover, propagation characteristics of WRC-15 candidate frequency bands proposed by China are measured and modeled to verify their effectiveness. For spectrum above 6GHz, the potential candidate frequency bands for 5G systems are selected based on the preliminary analysis of spectrum allocation, allotment and the current usage in China. Suggestions are provided for further studies on 5G spectrum.

关键词： IMT system 5G spectrum mobile service candidate frequency band 6GHz

Neighbor-Aware Multiple Access Protocol for 5G m MTC Applications

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China Communications 2016年第S2期13卷 80-88页

作者： Yang Yang Guannan Song Wuxiong Zhang Xiaohu Ge Chengxiang Wang Key Lab of wireless Sensor Networks & Communications Shanghai Institute of Microsystem and Information Technology (SIMIT) Chinese Academy of Sciences Shanghai Research center for wireless Communications University of Chinese Academy of Sciences School of Electronic Information and Communications Huazhong University of Science and Technology (HUST) Institute of Sensors Signals and Systems School of Engineering and Physical Sciences Heriot-Watt University

In order to support massive Machine Type Communication(mMTC) applications in future Fifth Generation(5G) systems,a key technical challenge is to design a highly effective multiple access protocol for massive connection requests and huge traffic load from all kinds of smart devices,***,watch,phone,ring,glasses,shoes,etc..To solve this hard problem in distributed scenarios with massive competing devices,this paper proposes and evaluates a Neighbor-Aware Multiple Access(NAMA) protocol,which is scalable and adaptive to different connectivity size and traffic *** exploiting acknowledgement signals broadcasted from the neighboring devices with successful packet transmissions,NAMA is able to turn itself from a contention-based random access protocol to become a contention-free deterministic access protocol with particular transmission schedules for all neighboring devices after a short transition *** performance of NAMA is fully evaluated from random state to deterministic state through extensive computer simulations under different network sizes and Contention Window(CW)*** with traditional IEEE802.11 Distributed Coordination Function(DCF),for a crowded network with 50 devices,NAMA can greatly improve system throughput and energy efficiency by more than 110%and210%,respectively,while reducing average access delay by 53%in the deterministic state.

关键词： neighbor-aware multiple access contention-based random access contention-free deterministic access ACK signal 802.11 DCF

Inter-Operator Interference Coordination for CoPrimary Spectrum Sharing in UDN

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China Communications 2015年第S1期12卷 104-112页

作者： YU Qiaoling WANG Jiang YANG Xiumei ZHU Yuanping TENG Yong Horneman Kari Shanghai Research center for wireless Communications Shanghai Institute of Microsystem and Information Technology (SIMIT) Chinese Academy of Sciences (CAS) Nokia

Co-primary spectrum sharing for multiple operators has been utilized to fully explore the spectrum resources and thus improve the spectrum efficiency. The inter-operator interference(IOI) problem should be seriously considered in order to achieve the mentioned target, especially under the scenario of the ultradense network(UDN) in the fifth generation(5G) wireless systems. To solve this problem, we propose an asymmetrical power levels based soft IOI coordination mechanism. The shared spectrum pool is consisted of three separated parts, where each part can be dynamically adjusted according to the minimal spectrum demand from each operator. Furthermore, different power masks are configured to different parts for each operator. The simulation results show that the proposed mechanism can improve the network spectrum efficiency significantly.

关键词： ultra-dense network inter-operator interference coordination co-primary spectrum sharing

AIRIS:Artificial Intelligence Enhanced Signal Processing in Reconfigurable Intelligent Surface Communications

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China Communications 2021年第7期18卷 158-171页

作者： Shun Zhang Muye Li Mengnan Jian Yajun Zhao Feifei Gao State Key Laboratory of integrated Services Networks Xidian UniversityXi’an 710071China Algorithm Department of wireless Product R&D Institute ZTE CorporationBeijing 100029China Institute for Artificial Intelligence Tsinghua University(THUAI)State Key Lab of Intelligent Technologies and SystemsTsinghua UniversityBeijing National Research Center for Information Science and Technology(BNRist)Department of AutomationTsinghua University Beijing100084China

Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications ***,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission *** the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real ***,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical *** one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,*** will also discuss the challenges of AIRIS and present some interesting future directions.

关键词： reconfigurable intelligent surface artifi-cial intelligence deep learning deep reinforcement learning signal processing

PIC-MF-based Iterative Receiver for Multiuser Space Frequency Block Coding systems

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Journal of Shanghai Jiaotong university(Science) 2007年第4期12卷 464-470页

作者：林文峰何晨熊勇 Dept.of Electronic Eng. Shanghai Jiaotong Univ. Shanghai Research center for wireless Communications

A novel low-complexity iterative receiver for multiuser space frequency block coding (SFBC) system was proposed in this paper. Unlike the conventional linear minimum mean square error (MMSE) detector, which requires matrix inversion at each iteration, the soft-in soft-out (SISO) detector is simply a parallel interference cancellation (PIC)-matched filter (MF) operation. The probability density function (PDF) of PIC-MF detector output is approximated as Gaussian, whose variance is calculated with a priori information fed back from the channel decoder. With this approximation, the log likelihood ratios (LLRs) of transmitted bits are under-estimated. Then the LLRs are multiplied by a constant factor to achieve a performance gain. The constant factor is optimized according to extrinsic information transfer (EXIT) chart of the SISO detector. Simulation results show that the proposed iterative receiver can significantly improve the system performance and converge to the matched filter bound (MFB) with low computational complexity at high signal-to-noise ratios (SNRs).

关键词： iterative multiuser space frequency block coding (SFBC) parallel interference cancellation (PIC) matched filter (MF) extrinsic information transfer (EXIT)

The event-driven paradigm for control,communication and optimization

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Journal of Control and Decision 2014年第1期1卷 3-17页

作者： Christos G.Cassandras Division of systems Engineering and center for Information and systems Engineering Boston UniversityBostonMAUSA

The event-driven paradigm offers an alternative to the time-driven paradigm for modelling,sampling,estimation,control and *** has come about largely as a consequence of systems being increasingly networked,wireless and consisting of distributed communicating *** key idea is that control actions need not be dictated by time steps taken by a“clock”;rather,an action should be triggered by an“event”which may be a well-defined condition on the system state,including the possibility of a simple time step,or a random state *** provide an overview of recent developments in event-driven approaches and focus on two areas to illustrate their ***,in distributed systems,we describe how event-driven,rather than synchronous,communication can guarantee convergence in cooperative distributed optimization while provably maintaining ***,in hybrid systems where events naturally decompose state trajectories into different discrete states(modes),we review the theory of infinitesimal perturbation analysis(IPA)which offers an event-driven“IPA calculus”for evaluating(or estimating in the case of stochastic systems)gradients of performance metrics,thus facilitating the solution of a large class of control and optimization problems.

关键词： event-driven control distributed systems hybrid systems infinitesimal perturbation analysis

Position Control of Flexible Joint Carts Using Adaptive Generalized Dynamics Inversion

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Computers, Materials & Continua 2022年第3期70卷 4691-4705页

作者： Ibrahim M.Mehedi Mohd Heidir Mohd Shah Soon Xin Ng Abdulah Jeza Aljohani Mohammed El-Hajjar Muhammad Moinuddin Department of Electrical and Computer Engineering(ECE) King Abdulaziz UniversityJeddah21589Saudi Arabia center of Excellence in Intelligent Engineering systems(CEIES) King Abdulaziz UniversityJeddah21589Saudi Arabia Next Generation wireless Research Group University of SouthamptonUK

This paper presents the design and implementation of Adaptive Generalized Dynamic Inversion(AGDI)to track the position of a Linear Flexible Joint Cart(LFJC)system along with vibration suppression of the flexible *** proposed AGDI control law will be comprised of two control *** baseline(continuous)control law is based on principle of conventional GDI approach and is established by prescribing the constraint dynamics of controlled state variables that reflect the control *** control law is realized by inverting the prescribed dynamics using dynamically scaledMoore-Penrose generalized *** boost the robust attributes against system nonlinearities,parametric uncertainties and external perturbations,a discontinuous control law will be augmented which is based on the concept of sliding mode *** discontinuous control law,the sliding mode gain is made adaptive in order to achieve improved tracking performance and chattering *** closed-loop stability of resultant control law is established by introducing a positive define Lyapunov candidate function such that semi-global asymptotic attitude tracking of LFJC system is *** computer simulations followed by experimental investigation will be performed on Quanser’s LFJC system to authenticate the feasibility of proposed control approach for its application to real world problems.

关键词： Adaptive control generalized dynamic inversion moore-penrose generalized inverse sliding mode control lyapunov stability semi-global asymptotic stability