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Group-based user pairing for virtual MIMO in LTE

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The Journal of China Universities of Posts and Telecommunications 2007年第3期14卷 38-42页

作者： QIAN Yu FAN Bin zheng kan Wireless Signal Processing and Network Laboratory Beijing University ofPosts and Telecommunications Beijing 100876 China

A user pairing method is proposed to improve the throughput gain of virtual multiple input multiple output （virtual MIMO） in 3G long-term evolution（LTE）. The approach taken in this study separated the user pairing into four steps： 1） the users are divided into two groups according to their signal-to-noise ratio （SNR）, and different user pairing metrics are proposed for each group; 2） the scheduler chooses a user for transmitting by a given rule; 3） the scheduler searches the pairing candidate for the selected user in each group; 4） the scheduler chooses the final pairing user from the co-group and crossover-group candidates by using a marginal utility function, to balance fairness and efficiency. The method can improve the throughput of users with high SNR, and guarantee fairness for users with low SNR, so it can be used in 3G LTE systems. The article provides both theoretical analysis and simulation results to support the idea.

关键词： virtual MIMO user pairing 3G LTE space division multiple access (SDMA)

Hole surface strengthening mechanism and riveting fatigue life of CFRP/aluminum stacks in robotic rotary ultrasonic drilling

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Chinese Journal of Aeronautics 2023年第10期36卷 471-484页

作者： Song DONG Wenhe LIAO kan zheng Feng XUE Lianjun SUN School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

Carbon fiber reinforced plastic(CFRP)and aluminum stacks are widely used in aviation industry due to light weight and high *** of rivet holes need to be drilled on body materials,and more than 80%of fatigue cracks occur at the connection holes,so the damage and residual stress of hole surface have crucial effect on the riveting fatigue life of CFRP/aluminum stacks and the flight ***,robotic rotary ultrasonic drilling(RRUD)technology is a promising method to machine the ***,the hole surface strengthening mechanism in RRUD and the service performance of the riveting joint are not ***,in this paper,the hole surface strengthening mechanism of RRUD for CFRP/aluminum stacks is investigated,a theoretical residual stress model is established,and the fatigue life experiment of riveted joints is ***,analysis on residual stress in RRUD is carried out with consideration of strengthening force and cutting *** stress model is established based on the calculation of elastic stress,plastic stress and stress *** experiment results show that ultrasonic vibration changes residual stress from tensile stress to compressive *** the same time,comparative damage analysis of CFRP hole exit and hole surface in robotic conventional drilling(RCD)and RRUD is ***,fatigue strength experiments of riveted joints are conducted for performance *** results indicate that fatigue life of single-hole riveted joints is increased by 68%with ultrasonic vibration,and four-hole riveted joint arranged according to aerospace design standards is increased by more than 86%.

关键词： CFRP/aluminum stacks Drilling damage Residual stress Riveting fatigue life Robotic rotary ultrasonic drilling

An intelligent self-sustained RAN slicing framework for diverse service provisioning in 5G-beyond and 6G networks

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Intelligent and Converged Networks 2020年第3期1卷 281-294页

作者： Jie Mei Xianbin Wang kan zheng Electrical and Computer Engineering Western UniversityLondonON N6A 5B9Canada Intelligent Computing and Communication(IC2)Lab Wireless Signal Processing and Network(WSPN)LabKey Laboratory of Universal Wireless CommunicationMinistry of EducationBeijing University of Posts and Telecommunications(BUPT)Beijing 100876China

Network slicing is a key technology to support the concurrent provisioning of heterogeneous Quality of Service(QoS)in the 5th Generation(5G)-beyond and the 6th Generation(6G)***,effective slicing of Radio Access Network(RAN)is very challenging due to the diverse QoS requirements and dynamic conditions in the 6G *** this paper,we propose a self-sustained RAN slicing framework,which integrates the self-management of network resources with multiple granularities,the self-optimization of slicing control performance,and self-learning together to achieve an adaptive control strategy under unforeseen network *** proposed RAN slicing framework is hierarchically structured,which decomposes the RAN slicing control into three levels,i.e.,network-level slicing,next generation NodeB(gNodeB)-level slicing,and packet scheduling level *** the network level,network resources are assigned to each gNodeB at a large timescale with coarse resource *** the gNodeB-level,each gNodeB adjusts the configuration of each slice in the cell at the large *** the packet scheduling level,each gNodeB allocates radio resource allocation among users in each network slice at a small ***,we utilize the transfer learning approach to enable the transition from a model-based control to an autonomic and self-learning RAN slicing *** the proposed RAN slicing framework,the QoS performance of emerging services is expected to be dramatically enhanced.

关键词： Radio Access Network(RAN) network slicing network resource management intelligent network

Multiuser beamforming based on max SINR for downlink spatial multiplexing MIMO

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The Journal of China Universities of Posts and Telecommunications 2007年第3期14卷 28-33页

作者： MA Peng-fei zheng kan WANG Wen-bo Wireless Signal Processing and Network Laboratory Beijing University ofPosts and Telecommunications Beijing 100876 China

In this article, a method based on max signal interference noise ratio（SINR） criterion is proposed, to mitigate the interuser interference for downlink multiuser spatial multiplexing multi-input multi-output（MIMO） systems. Unlike the zero forcing （ZF） scheme in which the SNR is decreased when the interference is eliminated completely, max SINR method makes a compromise between noise and interuser interference. When the number of substreams is larger than the difference between the number of base station antennas and the sum of interference mobile station antennas, the ZF is infeasible An existing coordinated TX-RX block diagonalization（COOR BD） method uses preprocessing at the receiver to cancel the interuser interference. However, it cannot obtain more receive diversity gain because of the preprocessing. Analysis and simulation show that the max SINR scheme has better performance than the ZF method. Moreover, when the ZF is infeasible, the max SINR scheme can obtain more receive diversity gain than COOR BD in the two-user case.

关键词： array signal processing beamforming MIMO systems spatial multiplexing

Chatter stability of robotic rotary ultrasonic countersinking

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Chinese Journal of Aeronautics 2023年第10期36卷 434-444页

作者： Zhenwen SUN Wenhe LIAO kan zheng Song DONG Pei LEI Lianjun SUN School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Chengdu Aircraft Industrial(Group)Co. Ltd.Chengdu 610091China

In recent years,industrial robots have received extensive attention in manufacturing field due to their high flexibility and great ***,the weak stiffness of industrial robots makes it extremely easy to arouse chatter,which affects machining quality inevitably and generates noise pollution in severe *** with drilling,the chatter mechanism of robotic countersinking is more *** external excitation changes with cutting width and depth in *** characteristic results in time-varying and nonlinearity of robotic countersinking ***,it is urgent to propose a new method of chatter suppression and provide an accurate stability analysis *** a new special machining technology,rotary ultrasonic machining has been proved to improve robotic drilling and milling stability *** on this,robotic rotary ultrasonic countersinking(RRUC)is proposed to improve the robotic countersinking stability in this paper.A three-dimensional stability domain method of RRUC is ***,the countersinking process was divided intoρ*** dynamic model of every unit was constructed based on ultrasonic function angle(γ)and dynamic chip ***,the stability region of RRUC is obtained based on the semi-discrete method(SDM).Compared with the robotic conventional countersinking(RCC),RRUC improves the stability by 27%.Finally,the correctness and effectiveness of the stability region model are proved by robotic ultrasonic countersinking experiments.

关键词： Industrial robot Rotary ultrasonic machining Dynamic model Countersinking chatter Stability analysis

Stability analysis of robotic longitudinal-torsional composite ultrasonic milling

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Chinese Journal of Aeronautics 2022年第8期35卷 249-264页

作者： Lianjun SUN Wenhe LIAO kan zheng Wei TIAN Jinshan LIU Jindan FENG School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China China Academy of Space Technology Beijing 100094China

Currently,industrial robots are considered as an alternative towards traditional machine *** for the large-scale parts milling,robotic flexibility and low cost make it possess the ***,the milling chatter caused by its weak rigidity hampers robotic application and promotion severely in aviation *** ultrasonic milling(RUM)technology with one-dimensional axial vibration has been proven and approved on avoiding robotic *** on this,the research of project team demonstrates that longitudinal-torsional composite ultrasonic milling(CUM-LT)involving separation characteristic has a greater advantage than RUM in terms of chatter ***,the CUM-LT as a new means is applied to avoid processing vibration of robotic milling *** its influence mechanism on stability improvement of weak stiffness processing system is ***,the approaches to strengthen separation effect are provided ***,a new analysis method of robotic CUM-LT(RCUM-LT)stability is proposed on the basis of ultrasonic function *** simulation and experimental results indicate that compared with robotic RUM(RRUM),stability regions of separated RCUM-LT(SRCUM-LT)and unseparated RCUM-LT(URCUM-LT)are improved by 124.42%and39.20%,*** addition of torsional ultrasonic energy has a wonderful effect on the milling chatter suppression of low stiffness robots.

关键词： Chatter suppression Industrial robots Longitudinal-torsional composite Rotary ultrasonic milling Stability analysis

Adaptive modulation for SVD-based MIMO systems with outdated CSI

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The Journal of China Universities of Posts and Telecommunications 2009年第4期16卷 78-83页

作者： YAN Zhi WANG Wen-bo WANG Xiao-ting zheng kan Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

The performance of singular value decomposition （SVD）-based multiple-input multiple-output （MIMO） with adaptive modulation （AM） is dependent on the accuracy of the channel state information （CSI） at the transmitter and the receiver. However, for a time-varying channel, the CSI obtained at the transmitter or the receiver is incorrect owing to an inherent delay or error. A typical system employing SVD suffers degradation in capacity when outdated CSI is used to transmit data. This article first addresses the adaptive modulation MIMO system designed under perfect CSI assumption. Based on that, two scenarios of outdated CSI are investigated and analyzed. The effect of imperfect CSI on the system performance is focused on and a simple post processing SNR （pSNR） adjustment design is proposed on AM system in the two scenarios for reducing degradation in average spectral efficiency （ASE）. Simulation results show that these designs provide good performance in an adaptive way, and enable the adaptive MIMO system considerably more to be robust against CSI imperfection.

关键词： MIMO SVD adaptive modulation ohtdated CSI

Joint linear precoder and power allocation design for uplink MIMO systems with limited feedback

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The Journal of China Universities of Posts and Telecommunications 2009年第3期16卷 14-18页

作者： YAN Zhi WANG Wen-bo WANG Jian-feng zheng kan Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In this article, the authors consider joint design of a linear precoder and power allocation for uplink multiuser multiple input multiple output （MIMO） communication systems with limited feedback to improve the bit error rate （BER） performance for all users. Precoder selection from the codebook set is directly based on the exact BER performance, instead of other suboptimal criteria, to achieve the optimal precoder matrix, but closed-form expressions may not exist in the view of power allocation based directly on the BER criterion. From this perspective, the authors propose the joint transmitter optimization algorithm for the consideration of precoder design, with total power constraint for asymptotic MBER （AMBER） criterion. In this AMBER criterion, a closed-form solution has been derived for power allocation with an optimal precoder. The simulation results show that the proposed joint design algorithm can achieve a much better performance than precoding with uniform power allocation and only consideration of power allocation.

关键词： MIMO linear precoder power allocation spatial multiplexing multiuser

Design and experiment of anti-adhesion rototiller based on staggered double-roller scraping

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International Journal of Agricultural and Biological Engineering 2024年第4期17卷 165-175页

作者： Jian Cheng Junfang Xia kan zheng Guoyang Liu Youshuai Wei Juan Zou College of Engineering Huazhong Agricultural UniversityWuhan 430070China Key Laboratory of Agricultural Equipment in Mid-lower Reaches of Yangtze River Ministry of Agriculture and Rural AffairsWuhan 430070China Hubei academy of agricultural sciences institute of food crops Wuhan 430070China

In order to solve the serious problem of soil adhering blade roller in the middle and lower reaches of Yangtze River,the anti-adhesion rototiller based on staggered double-roller scraping(ARSDS)was designed by mechanical scraping *** volume equation for scraping the soil adhesion part with staggered rotary blades was *** mechanical conditions for separation of soil adhesion part from blade roller were clarified,and the contact time between rotary blade and soil during rotary tillage was *** this way,the key parameters affecting soil adhering on and separating from the blade roller were determined,which were rotational speed,cutting pitch and tillage *** spatial and temporal trajectory changes for the sidelong section edge of staggered rotary blades were analyzed,so that the rotary blade arrangement was *** the discrete element method,selecting the soil adhesion mass on the staggered blade rollers as the response value established prediction model by Box-Behnken design *** example,taking the tillage depth of 14 cm for wheat cultivation in the middle and lower reaches of Yangtze River,the optimal combination of parameters was determined to be 230 r/min and 10 cm for rotational speed and cutting pitch,*** this time,the soil adhesion mass was 4566.67 *** the meantime,the process of soil particles adhering staggered blade rollers and rotary blades scraping off the adhering soil were *** experiments have shown that the operation quality of ARSDS met the requirements of rototiller performance *** the rice stubble field of high water moisture,the soil adhesion mass was 13.455 kg and 38.215 kg for ARSDS and conventional rototiller,respectively,which indicated that ARSDS effectively reducing soil adhesion *** research results can provide technical support for the design of rototiller reducing soil adhesion in the agricultural areas of the middle and lower reaches of the Yangtze River.

关键词： rice stubble field rotary tillage reducing soil adhesion staggered double-roller discrete element method