13 results on '"Liu Xiaochen"'
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2. Security‐reliability tradeoff analysis of joint relay‐user pair and friendly jammer selection for physical layer security against multiple eavesdroppers
- Author
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Nan Sha, Guangna Zhang, Huadong Luo, Mingxi Guo, Yuanyuan Gao, Liu Xiaochen, and Shijie Wang
- Subjects
Relay ,law ,Computer science ,Physical layer ,Electrical and Electronic Engineering ,Joint (audio engineering) ,Reliability (statistics) ,Selection (genetic algorithm) ,Computer Science Applications ,law.invention ,Reliability engineering - Published
- 2021
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3. Secrecy Rate Optimization for RF Powered Two-Hop Untrusted Relay Networks with Non-Linear EH Model
- Author
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Nan Sha, Guozhen Zang, Yuanyuan Gao, Liu Xiaochen, and Kui Xu
- Subjects
business.industry ,Computer science ,Applied Mathematics ,Computer Graphics and Computer-Aided Design ,law.invention ,Hop (networking) ,Nonlinear system ,Relay ,law ,Signal Processing ,Secrecy ,Electrical and Electronic Engineering ,business ,Computer network - Published
- 2020
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4. Enhancing Physical Layer Security Performance in Downlink Cellular Networks through Cooperative Users
- Author
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Nan Sha, Liu Xiaochen, Guangna Zhang, Yuanyuan Gao, Kui Xu, Mingxi Guo, and Shijie Wang
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business.industry ,Computer science ,Applied Mathematics ,Signal Processing ,Telecommunications link ,Cellular network ,Physical layer ,Electrical and Electronic Engineering ,business ,Computer Graphics and Computer-Aided Design ,Computer network - Published
- 2019
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5. Distributionally Robust Optimization for Secure Transmission With Assisting Jammer in MISO Downlink Networks
- Author
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Liu Xiaochen, Lei Wang, Shijie Wang, Yuanyuan Gao, and Nan Sha
- Subjects
Beamforming ,Mathematical optimization ,Optimization problem ,Wireless network ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Transmitter ,Robust optimization ,020206 networking & telecommunications ,Jamming ,Data_CODINGANDINFORMATIONTHEORY ,02 engineering and technology ,Covariance ,Transmitter power output ,Computer Science Applications ,Modeling and Simulation ,Telecommunications link ,0202 electrical engineering, electronic engineering, information engineering ,Artificial noise ,Electrical and Electronic Engineering ,Secure transmission ,Computer Science::Information Theory - Abstract
This letter investigates secure transmission with imperfect channel state information (CSI) in multi-input single-output downlink wireless networks that consist of a transmitter, a desired receiver, one eavesdropper, and an assisting jammer. Specifically, only rough first- and second-order moment information is obtained for the estimation errors of CSI. We aim to minimize the total transmit power by jointly designing the beamforming vector at transmitter and artificial noise covariance at jammer under the reliability and secrecy constraints for all the possible distributions of CSI errors. Since the chance-constrained optimization problem is non-convex, we reformulate it using a Lagrangian duality theory and semidefinite relaxation. The simulation results illustrate the validity of the proposed distributionally robust transmit scheme. more...
- Published
- 2019
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6. Secrecy Throughput Optimization for the WPCNs With Non-Linear EH Model
- Author
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Mingxi Guo, Liu Xiaochen, Nan Sha, and Yuanyuan Gao
- Subjects
General Computer Science ,business.industry ,Computer science ,Transmitter ,General Engineering ,secrecy throughput ,Throughput ,Data_CODINGANDINFORMATIONTHEORY ,physical layer security (PLS) ,Transmitter power output ,non-linear energy harvesting (EH) model ,Base station ,Wireless powered communication networks (WPCNs) ,Secure communication ,robust beamforming ,Artificial noise ,Wireless ,General Materials Science ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,business ,lcsh:TK1-9971 ,Communication channel ,Computer network ,Computer Science::Cryptography and Security ,Computer Science::Information Theory - Abstract
This paper investigates secure communication from a wireless-powered transmitter to a desired receiver with multiple eavesdroppers in the wireless powered communication networks (WPCNs). Considering the non-linear energy harvesting (EH) model, we propose a secure two-phase communication protocol with the help of a hybrid base station (HBS). First, in the power transfer (PT) phase, the HBS transfers wireless power to the transmitter. Then in the subsequent secure information transmission (SIT) phase, the transmitter sends the secret information using the energy harvested in the PT, under the protection of artificial noise (AN) generated by the HBS. First, based on this communication protocol, we maximize the secrecy throughput with perfect channel information state (CSI) under the transmit power constraint at the HBS. The secrecy throughput maximization (STM) problem is non-convex, and hence we reformulate it by exploiting the primal decomposition method (PDM) to obtain tractable forms. The PDM-based transmit scheme (PDM-TS) is proposed for the STM. In addition, considering the imperfect CSI of wiretap channel, we further design the robust transmit scheme for the worst-case secrecy throughput maximization (wSTM) problem. Since the wSTM shows high non-convexity, we extend the PDM by combining it with the S -procedure, and the PDM-based robust transmit scheme (PDM-RTS) is proposed for the wSTM. Finally, the numerical simulations are provided to show the effectiveness of the proposed transmit schemes. more...
- Published
- 2019
7. Distributionally Robust Secure Transmission for MISO Downlink Networks With Assisting Jammer
- Author
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Nan Sha, Mingxi Guo, Guozhen Zang, Liu Xiaochen, and Yuanyuan Gao
- Subjects
Beamforming ,Mathematical optimization ,convex optimization ,General Computer Science ,Computer science ,Transmitter ,General Engineering ,chance constraints ,distributionally robust beamforming ,Data_CODINGANDINFORMATIONTHEORY ,Covariance ,Transmitter power output ,Upper and lower bounds ,Robustness (computer science) ,assisting jammer ,Artificial noise ,General Materials Science ,Physical layer security ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:TK1-9971 ,Secure transmission ,Computer Science::Information Theory - Abstract
In this paper, we propose the distributionally robust secure transmit schemes in multi-input single-output (MISO) downlink wireless networks which consist of a transmitter, a desired receiver, multiple eavesdroppers and an assisting jammer. The imperfect channel state information (CSI) is considered and the CSI errors are only captured by the mean and covariance. We first study the transmit power minimization by jointly designing the beamforming vector at transmitter and artificial noise(AN) covariance at jammer, while the lower bound of connection probability at desired receiver and lower bound of outage probability at eavesdroppers are guaranteed simultaneously. Since the chance-constrained problem is non-convex, we derive two safe convex approximations by exploiting the Conditional Value-at-risk (CVaR) based method and Bernstein-type inequality (BTiE) based method, respectively. Specifically, we extend the application of BTiE originally proposed with the Gaussianity assumption to other possible distributions which satisfy the proposed sufficient condition. Furthermore, the secrecy rate maximization is exploited under the constraint of total transmit power. The original problem is non-convex and fractional, hence we design the Bilevel Quick Search (BQS) method to make it tractable. Finally, the simulation results verify the effectiveness and the robustness of the proposed transmit schemes. more...
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- 2019
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8. Robust optimal dispatch of power grid considering uncertainty of wind power output and electric vehicles
- Author
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Li Lei, Weidong Liu, Li Xiaohui, Li Dan, and Liu Xiaochen
- Subjects
Electric power system ,Mathematical optimization ,Wind power ,Optimization problem ,business.industry ,Total cost ,Computer science ,Scheduling (production processes) ,Grid connection ,Robust optimization ,business ,Grid - Abstract
With the extensive grid connection of wind power and the massive access of electric vehicles, their random nature has aggravated the difficulty of grid dispatching. In this paper, the idea of robust optimization is used to consider the uncertain factors faced by power grid dispatch, and the objective function is to minimize the total cost in extreme scenarios to establish a max-min optimization model for robust optimal dispatch of power grid. By adopting the column and constraint generation (C&CG) decomposition algorithm, the max-min double-layer optimization problem is decomposed into the main problem and the sub-problem iteratively, and a robust optimal scheduling scheme for dealing with uncertain factors is obtained. Finally, the IEEE 33-bus power system is taken as an example to carry out simulation analysis, and compared with the deterministic optimization scheduling method. The simulation results verify the effectiveness of the robust optimization scheduling model and solution algorithm in this paper. more...
- Published
- 2021
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9. Planning method for charging piles of intelligent networked electric vehicles in consideration of charging safety
- Author
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Li Dan, Weidong Liu, Yajian Zhang, Li Xiaohui, Liu Xiaochen, Li Lei, Ting Yang, and Yucheng Hou
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History ,Service (systems architecture) ,business.product_category ,Computer science ,Division (mathematics) ,Discount points ,Automotive engineering ,Computer Science Applications ,Education ,Software deployment ,Range (aeronautics) ,Electric vehicle ,business ,Pile ,Selection algorithm - Abstract
As the number of electric vehicles in cities increases, the charging demand has surged. Optimizing deployment planning of electric vehicle charging piles is of great significance to safe charging. Based on the analysis of the factors affecting the planning of electric vehicle charging piles and the spatial distribution characteristics of electric vehicles, this paper proposes a new planning method for urban intelligent networked electric vehicle charging piles that takes into account the charging safety. Using the point clustering algorithm, the optimal division of the urban electric vehicle service range is calculated, and then the central point selection algorithm is employed to allocate the optimal site. Taking the actual electric vehicle charging pile planning in one of the central cities as the experimental example, and comparing with tow of existing charging pile planning methods, the calculation results show that the method proposed in this paper has better planning effects and obtains more reasonable service regional division, balanced services amount, and shorter charging path distance, thus ensuring the safety of charging pile operation and service capabilities. more...
- Published
- 2021
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10. Evaluation of Lucas-Kanade based optical flow algorithm
- Author
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Tang Jun, Liu Xiaochen, Liu Jun, Yang Jiangtao, Wang Linwei, Shen Chong, Wang Yubo, Xiong Yufeng, and Liu Xiaojie
- Subjects
Lucas–Kanade method ,Computer science ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Optical flow ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Pyramid (image processing) ,Algorithm ,Urban environment - Abstract
Since the performance of pyramid Lucas-Kanade (LK) based optical flow algorithm would be influenced by different environments, this paper evaluates the simulation accuracy of the pyramid LK algorithm in cities, plains and mountains, respectively. The simulation results show that the LK algorithm can maintain high precision under the large motion, and the flight strategy of UAV under different environment is given according to the algorithm’s accuracy, In order to ensure the high accuracy of the optical flow sensor in different environments. For example, in the urban environment, when the UAV’s velocity is 12m/s-l5m/s, the best altitude is 80m-l50m. Simulation verification experiments are carried out in different environments. The simulation results show that the proposed UAV flight strategy is generally correct. more...
- Published
- 2018
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11. A high-sensitivity multilayer soil moisture monitoring sensor based on a double high-frequency tuning detection circuit
- Author
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Shi Yujiao, Shi Qinglan, Mei Shu-li, Liu Xiaochen, and Feng Lei
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010504 meteorology & atmospheric sciences ,Moisture ,Computer Networks and Communications ,Computer science ,General Engineering ,04 agricultural and veterinary sciences ,01 natural sciences ,lcsh:QA75.5-76.95 ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,lcsh:Electronic computers. Computer science ,Sensitivity (control systems) ,Water content ,0105 earth and related environmental sciences ,Remote sensing - Abstract
The multilayer soil moisture Internet of things sensor is designed to monitor the moisture of multiple soil profiles in real time. Its sensitivity and accuracy are of great concern to improve the performance of sensors. This article introduces the system composition of the end-cloud integrated multilayer soil moisture Internet of things sensor and then focuses on the design of key technologies, such as the moisture detection circuit, the time division multiplexing detection technology, and the deredundancy circuit in the analog–digital integrated design. The performance of the soil moisture detection circuit is directly related to the measurement accuracy of the sensor. A detection method is proposed using a high-frequency double-resonance circuit, which can detect small changes in moisture by changing the circuit detuning voltage. The maximum root mean square error of the calibration is less than 1.35% for five typical soils from different places. Compared with that of an independent detection method, the output consistency of the time division multiplexing detection is significantly improved by using the time division multiplexing detection method, which has a root mean square error of only 0.12%. In order to reduce errors caused by inconsistency in each burial, the gravimetric analysis is used in the sensitivity monitoring test, which shows that small changes in soil moisture can be detected by the circuit. more...
- Published
- 2020
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12. Microgrid Control Technology Based on Neural-Like P Systems with State Values
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Liu Yangyang, Liu Xiaochen, Liang Bin, Yang Guang, and Zehao He
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Control theory ,Computer science ,Control (management) ,State (computer science) ,Microgrid - Abstract
By utilizing the mobile energy storage characteristics and random dispersion of electric vehicles, it is coordinated with the wind power storage unit to optimize the economic and reliable operation of the system.In this paper, the integrated microgrid of wind, photovoltaic, energy storage and electric vehicle is studied. Under the premise of ensuring the safety and stability of the system, the control goal is to meet the needs of electric vehicles users as much as possible and to maximize the utilization ratio of new energy. The operation control strategies of power battery under disordered charging and orderly charging/discharging are considered respectively. Subsequently, the operation model of wind turbine generation and electric vehicles orderly charging/discharging is established by using the neural-like P system with "state value", and the operation modes of each unit are obtained according to the operation of microgrid. Finally, the effects of disordered charging and orderly charging/discharging of electric vehicles on the safe and stable operation of the microgrid system are compared by simulation experiments. more...
- Published
- 2019
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13. Verification Scheme and System Design of Charging Pile Electric Energy Measurement
- Author
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Li Xiaohui, Lei Li, Qi Zhou, Yang Guang, and Liu Xiaochen
- Subjects
business.product_category ,Comparator ,Computer science ,business.industry ,Instrumentation ,Electrical engineering ,GeneralLiterature_MISCELLANEOUS ,Power (physics) ,Charging station ,Reliability (semiconductor) ,Hardware_GENERAL ,Electric vehicle ,ComputingMilieux_COMPUTERSANDSOCIETY ,Systems design ,business ,Pile - Abstract
Design a charging pile electric energy verification device to improve the electric energy measurement accuracy of the charging pile. The device is mainly used for detecting whether the charging pile can be correctly configured, including a tariff period, a billing unit power, a billing rate, and the like, and detecting the communication reliability of the charging station. The test charges the pile output data by the broadband current comparator. Through RS485 communication mode, the instrumentation communication with the charging pile is always used to improve the accuracy of detection and measurement. The design and development of the DC charging pile verification device promoted the construction of the charging infrastructure and solved the charging problem of the electric vehicle. more...
- Published
- 2019
- Full Text
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