This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due ...This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.展开更多
Unlike regular stabilizations, we construct in the paper a specific feedback control system such that u(t) decays exponentially with the designated decay rate, and that some non-trivial linear functionals of u decay e...Unlike regular stabilizations, we construct in the paper a specific feedback control system such that u(t) decays exponentially with the designated decay rate, and that some non-trivial linear functionals of u decay exactly faster than . The system contains a dynamic compensator with another state v in the feedback loop, and consists of two states u and v. This problem entirely differs from the one with static feedback scheme in which the system consists only of a single state u. To show the essential difference, some specific property of the spectral subspaces associated with our control system is studied.展开更多
Deformable mirrors are essential dynamic wavefront compensation.Among the various types of deformable mirrors with different actuation mechanisms,the unimorph piezoelectric deformable mirror(UPDM)offers distinct advan...Deformable mirrors are essential dynamic wavefront compensation.Among the various types of deformable mirrors with different actuation mechanisms,the unimorph piezoelectric deformable mirror(UPDM)offers distinct advantages owing to its compact size and low cost.The two most critical challenges in UPDM are electrode fabrication and deformation control.This study proposes an integrated electrode fabrication and sensorless feedback control scheme for UPDM,which simplifies the manufacturing process and enhances its performance.The electrode array is created using silkscreen printing combined with flexible printed circuit board technology,integrating electrode fabrication and electrical connection into a single step.The desired mirror deformation is achieved by introducing a closed-loop direct deformation control method based on piezoelectric self-sensing.The feedback mechanism utilizes the local strain-induced charge generated by the piezoelectric plate,effectively addressing the nonlinear behavior of the piezoelectric material.Experimental results confirm the feasibility and effectiveness of the proposed method,with the maximum relative error in the steady state phase remaining below 2%.展开更多
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2006AA01Z272 and 2009AA02Z412)the Beijing Municipal Science & Technology Commission(Grant No.D08080100620802)
文摘This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.
文摘Unlike regular stabilizations, we construct in the paper a specific feedback control system such that u(t) decays exponentially with the designated decay rate, and that some non-trivial linear functionals of u decay exactly faster than . The system contains a dynamic compensator with another state v in the feedback loop, and consists of two states u and v. This problem entirely differs from the one with static feedback scheme in which the system consists only of a single state u. To show the essential difference, some specific property of the spectral subspaces associated with our control system is studied.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB1050000)in part by the CAS Project for Young Scientists in Basic Research(YSBR-066)+2 种基金in part by the National Science Foundation of China(T2122001)in part by the capital construction funds within the budget of Jilin Province(2023C030-6)in part by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y2021065).
文摘Deformable mirrors are essential dynamic wavefront compensation.Among the various types of deformable mirrors with different actuation mechanisms,the unimorph piezoelectric deformable mirror(UPDM)offers distinct advantages owing to its compact size and low cost.The two most critical challenges in UPDM are electrode fabrication and deformation control.This study proposes an integrated electrode fabrication and sensorless feedback control scheme for UPDM,which simplifies the manufacturing process and enhances its performance.The electrode array is created using silkscreen printing combined with flexible printed circuit board technology,integrating electrode fabrication and electrical connection into a single step.The desired mirror deformation is achieved by introducing a closed-loop direct deformation control method based on piezoelectric self-sensing.The feedback mechanism utilizes the local strain-induced charge generated by the piezoelectric plate,effectively addressing the nonlinear behavior of the piezoelectric material.Experimental results confirm the feasibility and effectiveness of the proposed method,with the maximum relative error in the steady state phase remaining below 2%.
