Maritime channel modeling can be affected by some key time-varying environmental factors.The ducting effect is one of the thorniest factors since it causes anomalous propagation enhancement and severe co-channel inter...Maritime channel modeling can be affected by some key time-varying environmental factors.The ducting effect is one of the thorniest factors since it causes anomalous propagation enhancement and severe co-channel interference.Moreover,the atmospheric attenuation is much more severe in the ocean environment,resulting in shorter coverage distance and more link outage.In this paper,we propose an environmental information-aided electromagnetic propagation testbed.It is based on complex refractivity estimation and improved parabolic equation propagation model,taking into account both ducting effect and atmospheric attenuation.A large-scale temporal and spatial propagation measurement was conducted with meteorological acquisition.We consider practical path loss and ducting conditions to verify the testbed feasibility in these long-distance radio links.The simulation results are in good agreement with the measured data,which further reveal the basic temporal and spatial distribution of ducting effect at 3.5 GHz band.展开更多
提出采用LDRA(Liverpool Data Research Associates Ltd.)TESTBED测试工具辅助完成高可靠性的军用软件测试工作,并通过测试实例阐述了该工具在航天软件测试中的应用方案。结果证明,合理使用该工具,能够有效避免人为失误,提高软件测试的...提出采用LDRA(Liverpool Data Research Associates Ltd.)TESTBED测试工具辅助完成高可靠性的军用软件测试工作,并通过测试实例阐述了该工具在航天软件测试中的应用方案。结果证明,合理使用该工具,能够有效避免人为失误,提高软件测试的效率和信息采集的准确度。展开更多
In-situ exploration of asteroid surfaces is of great scientific significance.Internally actuated rovers have been released to asteroid surfaces but without enough controllability.To investigate the attitude control ch...In-situ exploration of asteroid surfaces is of great scientific significance.Internally actuated rovers have been released to asteroid surfaces but without enough controllability.To investigate the attitude control characteristics of the cubic rover for asteroid surface exploration,a series of experiments are carried out using the self-designed rover and the low-gravity testbed.The experiments focus on two major themes:The minimum flywheel speed for cubic rover to produce a walking motion in different conditions,and the relationship between the rover’s rotation angle and the flywheel speed in twisting motion.The rover’s dynamical descriptions of the walking and twisting motions are first derived.The features and design of the low-gravity testbed are then summarized,including its dynamics,setup,and validation.A detailed comparison between the dynamic model and the experimental results is presented,which provides a basic reference of the cubic rover’s attitude control in low-gravity environments.展开更多
Various distributed cooperative control schemes have been widely utilized for cyber-physical power system(CPPS),which only require local communications among geographic neighbors to fulfill certain goals.However,the p...Various distributed cooperative control schemes have been widely utilized for cyber-physical power system(CPPS),which only require local communications among geographic neighbors to fulfill certain goals.However,the process of evaluating the performance of an algorithm for a CPPS can be affected by the physical target characteristics and real communication conditions.To address this potential problem,a testbed with controller hardware-in-the-loop(CHIL)is proposed in this paper.On the basis of a power grid simulation conducted using the real-time simulator RT-LAB developed by the company OPAL-RT,along with a communication network simulation developed with OPNET,multiple distributed controllers were developed with hardware devices to directly collect the real-time operating data of the power system model in RT-LAB and provide local control.Furthermore,the communication between neighboring controllers was realized using the cyber system modelin OPNET with an Ethernet interface.The hardware controllers produced a real-world control behavior instead of a digital simulation,and precisely simulated the dynamic features of a CPPS with high speed.A classic cooperative control case for active power output was studied to explain the integrated simulation process and validate the effectiveness of the co-simulation testbed.展开更多
Multiple-Input Multiple-Output （MIMO） and Orthogonal Frequency Division Multiplexing （OFDM） have been widely accepted as key techniques of the current and future wireless communication systems. In this paper, an o...Multiple-Input Multiple-Output （MIMO） and Orthogonal Frequency Division Multiplexing （OFDM） have been widely accepted as key techniques of the current and future wireless communication systems. In this paper, an open access MIMO testbed is presented, on which the researchers can demonstrate and evaluate their baseband algorithms over the real wireless channel, without knowing much details about the hardware of the testbed. Moreover, an IEEE 802.11n transmission scheme is implemented as a design example to validate this testbed as well as demonstrate the transmission characteristics of MIMO-OFDM.展开更多
The sub-6 G band is too crowded to accommodate higher data rate, while the millimeter wave(mmWave) bands have abundant spectrum resources and massive MIMO can provide high spectral and energy efficiency. Therefore, th...The sub-6 G band is too crowded to accommodate higher data rate, while the millimeter wave(mmWave) bands have abundant spectrum resources and massive MIMO can provide high spectral and energy efficiency. Therefore, the combination of the two,namely mmWave-MIMO system, has attracted intensive research interests. In this paper, we develop a high-speed mmWave-MIMO communication system and conduct exhaustive field tests. The detail of the system design is provided and the key modules of the testbed are analyzed. The testbed exploits high gain of mmWave RF and flexible configuration of embedded system. The validation and field tests show that the developed testbed can provide up to 2.3 Gbps network layer data rate in single channel with low latency and support point-to-multi-point(PtMP) transmission aided by relay. The testbed can be used in future B5 G and 6 G systems to provide high reliability and low latency wireless coverage.展开更多
基金supported in part by the National Key Research and Development Program of China(No.2018YFB1802300)the National Natural Science Foundation of China(No.61801461,No.61925105)+1 种基金in part by the Shanghai Municipality of Science and Technology Commission Project(Nos.20JC1416500)the Program of Shanghai Academic/Technology Research Leader(Nos.21XD1433700)。
文摘Maritime channel modeling can be affected by some key time-varying environmental factors.The ducting effect is one of the thorniest factors since it causes anomalous propagation enhancement and severe co-channel interference.Moreover,the atmospheric attenuation is much more severe in the ocean environment,resulting in shorter coverage distance and more link outage.In this paper,we propose an environmental information-aided electromagnetic propagation testbed.It is based on complex refractivity estimation and improved parabolic equation propagation model,taking into account both ducting effect and atmospheric attenuation.A large-scale temporal and spatial propagation measurement was conducted with meteorological acquisition.We consider practical path loss and ducting conditions to verify the testbed feasibility in these long-distance radio links.The simulation results are in good agreement with the measured data,which further reveal the basic temporal and spatial distribution of ducting effect at 3.5 GHz band.
基金the National Natural Science Foundation of China(No.11972075)the Innovation Research Program of Beijing Institute of Technology(No.2021CX01029)。
文摘In-situ exploration of asteroid surfaces is of great scientific significance.Internally actuated rovers have been released to asteroid surfaces but without enough controllability.To investigate the attitude control characteristics of the cubic rover for asteroid surface exploration,a series of experiments are carried out using the self-designed rover and the low-gravity testbed.The experiments focus on two major themes:The minimum flywheel speed for cubic rover to produce a walking motion in different conditions,and the relationship between the rover’s rotation angle and the flywheel speed in twisting motion.The rover’s dynamical descriptions of the walking and twisting motions are first derived.The features and design of the low-gravity testbed are then summarized,including its dynamics,setup,and validation.A detailed comparison between the dynamic model and the experimental results is presented,which provides a basic reference of the cubic rover’s attitude control in low-gravity environments.
基金the National Key Research and Development Program of China(Basic Research Class)(No.2017YFB0903000)the National Natural Science Foundation of China(No.U1909201).
文摘Various distributed cooperative control schemes have been widely utilized for cyber-physical power system(CPPS),which only require local communications among geographic neighbors to fulfill certain goals.However,the process of evaluating the performance of an algorithm for a CPPS can be affected by the physical target characteristics and real communication conditions.To address this potential problem,a testbed with controller hardware-in-the-loop(CHIL)is proposed in this paper.On the basis of a power grid simulation conducted using the real-time simulator RT-LAB developed by the company OPAL-RT,along with a communication network simulation developed with OPNET,multiple distributed controllers were developed with hardware devices to directly collect the real-time operating data of the power system model in RT-LAB and provide local control.Furthermore,the communication between neighboring controllers was realized using the cyber system modelin OPNET with an Ethernet interface.The hardware controllers produced a real-world control behavior instead of a digital simulation,and precisely simulated the dynamic features of a CPPS with high speed.A classic cooperative control case for active power output was studied to explain the integrated simulation process and validate the effectiveness of the co-simulation testbed.
文摘Multiple-Input Multiple-Output （MIMO） and Orthogonal Frequency Division Multiplexing （OFDM） have been widely accepted as key techniques of the current and future wireless communication systems. In this paper, an open access MIMO testbed is presented, on which the researchers can demonstrate and evaluate their baseband algorithms over the real wireless channel, without knowing much details about the hardware of the testbed. Moreover, an IEEE 802.11n transmission scheme is implemented as a design example to validate this testbed as well as demonstrate the transmission characteristics of MIMO-OFDM.
基金supported by National Key R&D Program of China ( 2020YFB1807204)。
文摘The sub-6 G band is too crowded to accommodate higher data rate, while the millimeter wave(mmWave) bands have abundant spectrum resources and massive MIMO can provide high spectral and energy efficiency. Therefore, the combination of the two,namely mmWave-MIMO system, has attracted intensive research interests. In this paper, we develop a high-speed mmWave-MIMO communication system and conduct exhaustive field tests. The detail of the system design is provided and the key modules of the testbed are analyzed. The testbed exploits high gain of mmWave RF and flexible configuration of embedded system. The validation and field tests show that the developed testbed can provide up to 2.3 Gbps network layer data rate in single channel with low latency and support point-to-multi-point(PtMP) transmission aided by relay. The testbed can be used in future B5 G and 6 G systems to provide high reliability and low latency wireless coverage.
