Reaction control system(RCS) is a powerful and efficient actuator for space vehicles attitude control, which is typically characterized as a pulsed unilateral effector only with two states(off/on). Along with inevitab...Reaction control system(RCS) is a powerful and efficient actuator for space vehicles attitude control, which is typically characterized as a pulsed unilateral effector only with two states(off/on). Along with inevitable internal uncertainties and external disturbances in practice, this inherent nonlinear character always hinders space vehicles autopilot from pursuing precise tracking performance. Compared to most of pre-existing methodologies that passively suppress the uncertainties and disturbances, a design based on predictive functional control(PFC) and generalized extended state observer(GESO) is firstly proposed for three-axis RCS control system to actively reject that with no requirement for additional fuel consumption. To obtain a high fidelity predictive model on which the performance of PFC greatly depends, the nonlinear coupling multiple-input multiple-output(MIMO) flight dynamics model is parameterized as a state-dependent coefficient form. And based on that, a MIMO PFC algorithm in state space domain for a plant of arbitrary orders is deduced in this paper.The internal uncertainties and external disturbances are lumped as a total disturbance, which is estimated and cancelled timely to further enhance the robustness. The continuous control command synthesised by above controller-rejector tandem is finally modulated by pulse width pulse frequency modulator(PWPF) to on-off signals to meet RCS requirement. The robustness and feasibility of the proposed design are validated by a series of performance comparison simulations with some prominent methods in the presence of significant perturbations and disturbances, as well as measurement noise.展开更多
This study addresses the challenges of near-field interference suppression and resource allocation in extremely large-scale multiple-input multiple-output(XL-MIMO)communication systems,particularly under denseuser sce...This study addresses the challenges of near-field interference suppression and resource allocation in extremely large-scale multiple-input multiple-output(XL-MIMO)communication systems,particularly under denseuser scenarios.We propose a quality-of-service(QoS)-aware joint user scheduling and power control scheme.Leveraging the spherical wave(SW)characteristics of near field channels,a dual-domain interference suppression strategy is developed by analyzing the spatial correlation of beam focusing vectors in terms of both angular separation and distance constraints.Based on this,a spatial correlation-based scheduling(SCS)algorithm is designed.By integrating this user selection strategy with a dynamic power allocation mechanism,the proposed approach optimizes the sum spectral efficiency while ensuring the user QoS.This framework is further extended to modular XL-MIMO systems.We show how modular deployment can enhance spatial resolution and develop an adapted QoS-aware user scheduling algorithm,called modular SCS(SCS-mod),for this architecture.Simulation results validate that the proposed algorithms significantly outperform existing schemes in terms of sum spectral efficiency and the number of scheduled users,especially under high user density and high transmission power conditions.展开更多
A multi-band multi-antenna system has become an important trend in the development of mobile communication systems.However,strong mutual coupling tends to occur between antenna elements with a small space,distorting a...A multi-band multi-antenna system has become an important trend in the development of mobile communication systems.However,strong mutual coupling tends to occur between antenna elements with a small space,distorting array antennas’performance.Therefore,in the multiple-input multiple-output(MIMO)antenna system,high isolation based on miniaturization of the antenna array has been pursued.We study in depth the methods of decoupling between antenna elements.Reasons for the existence of mutual coupling and advantages of mutual coupling reduction are analyzed.Then the decoupling methods proposed in recent works are compared and analyzed.Finally,we propose a metasurface consisting of double-layer short wires,which can be applied to improve the port isolation of antennas arranged along the H-plane and E-plane.Results show that the proposed metasurface has good decoupling effect on a closely placed antenna array.展开更多
We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G an...We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G and WLAN are spaced to reduce coupling between antenna elements in the same module.The return loss of all antenna elements is larger than 6 dB.The isolation between all elements is larger than 14 dB.The radiation efficiency of the high-frequency antenna is greater than 50%,and the radiation efficiency of the low-frequency antenna is greater than 40%.The far-field gain of all elements is greater than 2.2 dBi.展开更多
文摘Reaction control system(RCS) is a powerful and efficient actuator for space vehicles attitude control, which is typically characterized as a pulsed unilateral effector only with two states(off/on). Along with inevitable internal uncertainties and external disturbances in practice, this inherent nonlinear character always hinders space vehicles autopilot from pursuing precise tracking performance. Compared to most of pre-existing methodologies that passively suppress the uncertainties and disturbances, a design based on predictive functional control(PFC) and generalized extended state observer(GESO) is firstly proposed for three-axis RCS control system to actively reject that with no requirement for additional fuel consumption. To obtain a high fidelity predictive model on which the performance of PFC greatly depends, the nonlinear coupling multiple-input multiple-output(MIMO) flight dynamics model is parameterized as a state-dependent coefficient form. And based on that, a MIMO PFC algorithm in state space domain for a plant of arbitrary orders is deduced in this paper.The internal uncertainties and external disturbances are lumped as a total disturbance, which is estimated and cancelled timely to further enhance the robustness. The continuous control command synthesised by above controller-rejector tandem is finally modulated by pulse width pulse frequency modulator(PWPF) to on-off signals to meet RCS requirement. The robustness and feasibility of the proposed design are validated by a series of performance comparison simulations with some prominent methods in the presence of significant perturbations and disturbances, as well as measurement noise.
基金Project supported by the Basic and Applied Basic Research Foundation in Guangdong(No.2023A1515011980)the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province(No.BK20240070)+2 种基金the Program for Innovative Talents and Entrepreneur in Jiangsu(No.1104000402)the National Natural Science Foundation of China(No.62371289)the Shanghai Jiao Tong University 2030 Initiative。
文摘This study addresses the challenges of near-field interference suppression and resource allocation in extremely large-scale multiple-input multiple-output(XL-MIMO)communication systems,particularly under denseuser scenarios.We propose a quality-of-service(QoS)-aware joint user scheduling and power control scheme.Leveraging the spherical wave(SW)characteristics of near field channels,a dual-domain interference suppression strategy is developed by analyzing the spatial correlation of beam focusing vectors in terms of both angular separation and distance constraints.Based on this,a spatial correlation-based scheduling(SCS)algorithm is designed.By integrating this user selection strategy with a dynamic power allocation mechanism,the proposed approach optimizes the sum spectral efficiency while ensuring the user QoS.This framework is further extended to modular XL-MIMO systems.We show how modular deployment can enhance spatial resolution and develop an adapted QoS-aware user scheduling algorithm,called modular SCS(SCS-mod),for this architecture.Simulation results validate that the proposed algorithms significantly outperform existing schemes in terms of sum spectral efficiency and the number of scheduled users,especially under high user density and high transmission power conditions.
基金Project supported by the National Natural Science Foundation of China(No.61701366).
文摘A multi-band multi-antenna system has become an important trend in the development of mobile communication systems.However,strong mutual coupling tends to occur between antenna elements with a small space,distorting array antennas’performance.Therefore,in the multiple-input multiple-output(MIMO)antenna system,high isolation based on miniaturization of the antenna array has been pursued.We study in depth the methods of decoupling between antenna elements.Reasons for the existence of mutual coupling and advantages of mutual coupling reduction are analyzed.Then the decoupling methods proposed in recent works are compared and analyzed.Finally,we propose a metasurface consisting of double-layer short wires,which can be applied to improve the port isolation of antennas arranged along the H-plane and E-plane.Results show that the proposed metasurface has good decoupling effect on a closely placed antenna array.
基金supported by the National and Local Joint Engineering Laboratory of RF Integration and Micro-Assembly Technology,China(No.KFJJ20170206)the Research Project of Nanjing University of Posts and Telecommunications,China(No.208035)the University of Macao,China(No.CPG2019-00024-FST)。
文摘We propose a dual-module multiple-input multiple-output(MIMO)antenna for portable terminals.The operating bands of the handheld terminal antenna are 5G(3.4–3.8 GHz)and WLAN(5.150–5.925 GHz).Antenna elements of 5G and WLAN are spaced to reduce coupling between antenna elements in the same module.The return loss of all antenna elements is larger than 6 dB.The isolation between all elements is larger than 14 dB.The radiation efficiency of the high-frequency antenna is greater than 50%,and the radiation efficiency of the low-frequency antenna is greater than 40%.The far-field gain of all elements is greater than 2.2 dBi.
