To provide global service with low latency, the broadband low earth orbits (LEO) satellite constellation based communication systems have become one of the focuses in academic and industry. To allow for wideband acces...To provide global service with low latency, the broadband low earth orbits (LEO) satellite constellation based communication systems have become one of the focuses in academic and industry. To allow for wideband access for user links, the feeder link of LEO satellite is correspondingly required to support high throughput data communications. To this end, we propose to apply line-of-sight (LoS) multiple-input multiple-output (MIMO) transmission for the feeder link to achieve spatial multiplexing by optimizing the antenna arrangement. Unlike the LoS MIMO applications for static scenarios, the movement of LEO satellites make it impractical to adjust the optimal antenna separation for all possible satellite positions. To address this issue, we propose to design the antenna placement to maximize the ergodic channel capacity during the visible region of the ground station. We first derive the closed-form probability distribution of the satellite trajectory in visible region. Based on which the ergodic channel capacity can be then calculated numerically. The antenna placement can be further optimized to maximize the ergodic channel capacity. Numerical results verify the derived probability distribution of the satellite trajectory, and show that the proposed LoS MIMO scheme can significantly increase the ergodic channel capacity compared with the existing SISO one.展开更多
People continue to recognize the important role of Chinese medicine in the treatment of diseases,and there is an urgent need to clarify the mechanism of Chinese medicine.Because of the multi-target and multi-component...People continue to recognize the important role of Chinese medicine in the treatment of diseases,and there is an urgent need to clarify the mechanism of Chinese medicine.Because of the multi-target and multi-component characteristics of traditional Chinese medicine,it is difficult to elaborate from a single perspective.As a high-quality animal model,Caenorhabditis elegans with the characteristics of small size and fast reproduction,has been widely used in traditional Chinese medicine activity experiments.In this article,Caenorhabditis elegans,as model organisms used to screen the active components of traditional Chinese medicine were reviewed.展开更多
基金supported by the National Key R&D Program of China under Grant 2019YFB1803102
文摘To provide global service with low latency, the broadband low earth orbits (LEO) satellite constellation based communication systems have become one of the focuses in academic and industry. To allow for wideband access for user links, the feeder link of LEO satellite is correspondingly required to support high throughput data communications. To this end, we propose to apply line-of-sight (LoS) multiple-input multiple-output (MIMO) transmission for the feeder link to achieve spatial multiplexing by optimizing the antenna arrangement. Unlike the LoS MIMO applications for static scenarios, the movement of LEO satellites make it impractical to adjust the optimal antenna separation for all possible satellite positions. To address this issue, we propose to design the antenna placement to maximize the ergodic channel capacity during the visible region of the ground station. We first derive the closed-form probability distribution of the satellite trajectory in visible region. Based on which the ergodic channel capacity can be then calculated numerically. The antenna placement can be further optimized to maximize the ergodic channel capacity. Numerical results verify the derived probability distribution of the satellite trajectory, and show that the proposed LoS MIMO scheme can significantly increase the ergodic channel capacity compared with the existing SISO one.
基金This work was financially supported by Scientific Research Fund Project of Education Department of Liaoning Province(LJKZ0960)Science Foundation of Shenyang Pharmaceutical University(GGJJ2021105).
文摘People continue to recognize the important role of Chinese medicine in the treatment of diseases,and there is an urgent need to clarify the mechanism of Chinese medicine.Because of the multi-target and multi-component characteristics of traditional Chinese medicine,it is difficult to elaborate from a single perspective.As a high-quality animal model,Caenorhabditis elegans with the characteristics of small size and fast reproduction,has been widely used in traditional Chinese medicine activity experiments.In this article,Caenorhabditis elegans,as model organisms used to screen the active components of traditional Chinese medicine were reviewed.
