The rapid development and continuous updating of the mega satellite constellation(MSC)have brought new visions for the future 6G coverage extension, where the global seamless signal coverage can realize ubiquitous ser...The rapid development and continuous updating of the mega satellite constellation(MSC)have brought new visions for the future 6G coverage extension, where the global seamless signal coverage can realize ubiquitous services for user terminals. However, global traffic demands present nonuniform characteristics. Therefore, how to ensure the on-demand service coverage for the specific traffic demand, i.e., the ratio of traffic density to service requirement per unit area, is the core issue of 6G wireless coverage extension exploiting the MSC. To this regard, this paper first discusses the open challenges to reveal the future direction of 6G wireless coverage extension from the perspective of key factors affecting service coverage performance, i.e., the network access capacity, space segment capacity and their matchingrelationship. Furthermore, we elaborate on the key factors affecting effective matchings of the aforementioned aspects, thereby improving service coverage capability.展开更多
Schema matching is a critical step in the integration of heterogeneous web service,which contains various types of web services and multi-version services of the same type.Mapping loss or mismatch usually occurs due t...Schema matching is a critical step in the integration of heterogeneous web service,which contains various types of web services and multi-version services of the same type.Mapping loss or mismatch usually occurs due to schema differences in structure and content and the variety in concept definition and organization.Current instance schema matching methods are not mature enough for heterogeneous web service because they cannot deal with the instance data in web service domain and capture all the semantics,especially metadata semantics.The metadata-based and the instance-based matching methods,in the case of being employed individually,are not efficient to determine the concept relationships,which are crucial for finding high-quality matches between schema attributes.In this paper,we propose an improved schema matching method,based on the combination of instance and metadata(CIM)matcher.The main method of our approach is to utilize schema structure,element labels,and the corresponding instance data information.The matching process is divided into two phases.In the first phase,the metadata-based matchers are used to compute the element label similarity of multi-version open geospatial consortium web service schema,and the generated matching results are raw mappings,which will be reused in the next instance matching phase.In the second phase,the designed instance matching algorithms are employed to the instance data of the raw mappings and fine mappings are generated.Finally,the raw mappings and the fine mappings are combined,and the final mappings are obtained.Our experiments are executed on different versions of web coverage service and web feature service instance data deployed in Geoserver.The results indicate that,the CIM method can obtain more accurate matching results and is flexible enough to handle the web service instance data.展开更多
The active multi-beam antenna can be widely used in the 6G integrated satellite network project,the national satellite Internet project,and other major satellite projects.It determines the key performance indicators o...The active multi-beam antenna can be widely used in the 6G integrated satellite network project,the national satellite Internet project,and other major satellite projects.It determines the key performance indicators of the satellite such as the service coverage area and the communication capacity of all the beams in the forward link and the return link.The active multi-beam antenna is the core technology of satellite payload and has been developed rapidly in recent years.Based on the antenna performance requirements such as the number of giant-scale beams,super-large coverage area,high gain,and high carrier-to-interference ratio(C/I),this paper proposes a new active multi-beam antenna design method,which integrates the multi-objective coordination and multi-feed amplitude and phase weighted optimization algorithms.A balanced optimal solution that meets the performance requirements can be obtained by constraining each other with different objective functions.In the optimization process,the surrogate model of convolutional autoencoder based on artificial intelligence technology is proposed for multi-objective optimization solution,which efficiently completes the search of optimal beam excitation coefficients.This paper takes the demand for very-high-throughput communication satellites serving the Asia-Pacific region as an example and applies the design method to the multi-beam antenna design of the satellite.The simulation verification of the antenna is completed,achieving good performance of 976 beams.All results meet the performance requirements,supporting the implementation of 1 Tbps communication capacity for the entire satellite,and verifying the correctness of the design method.展开更多
基金supported in part by the National Key R&D Program of China under Grant 2020YFB1806100in part by the Natural Science Foundation of China under Grants U19B2025, 62121001, 62001347, and 61801361。
文摘The rapid development and continuous updating of the mega satellite constellation(MSC)have brought new visions for the future 6G coverage extension, where the global seamless signal coverage can realize ubiquitous services for user terminals. However, global traffic demands present nonuniform characteristics. Therefore, how to ensure the on-demand service coverage for the specific traffic demand, i.e., the ratio of traffic density to service requirement per unit area, is the core issue of 6G wireless coverage extension exploiting the MSC. To this regard, this paper first discusses the open challenges to reveal the future direction of 6G wireless coverage extension from the perspective of key factors affecting service coverage performance, i.e., the network access capacity, space segment capacity and their matchingrelationship. Furthermore, we elaborate on the key factors affecting effective matchings of the aforementioned aspects, thereby improving service coverage capability.
基金This work was supported by the National Natural Science Foundation of China[grant number 41201393]the Open Research Fund of State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing of Wuhan University[grant number 14I03].
文摘Schema matching is a critical step in the integration of heterogeneous web service,which contains various types of web services and multi-version services of the same type.Mapping loss or mismatch usually occurs due to schema differences in structure and content and the variety in concept definition and organization.Current instance schema matching methods are not mature enough for heterogeneous web service because they cannot deal with the instance data in web service domain and capture all the semantics,especially metadata semantics.The metadata-based and the instance-based matching methods,in the case of being employed individually,are not efficient to determine the concept relationships,which are crucial for finding high-quality matches between schema attributes.In this paper,we propose an improved schema matching method,based on the combination of instance and metadata(CIM)matcher.The main method of our approach is to utilize schema structure,element labels,and the corresponding instance data information.The matching process is divided into two phases.In the first phase,the metadata-based matchers are used to compute the element label similarity of multi-version open geospatial consortium web service schema,and the generated matching results are raw mappings,which will be reused in the next instance matching phase.In the second phase,the designed instance matching algorithms are employed to the instance data of the raw mappings and fine mappings are generated.Finally,the raw mappings and the fine mappings are combined,and the final mappings are obtained.Our experiments are executed on different versions of web coverage service and web feature service instance data deployed in Geoserver.The results indicate that,the CIM method can obtain more accurate matching results and is flexible enough to handle the web service instance data.
基金supported by the Fund from the National Natural Science Foundation of China(Grant No.62271387)a pre-research project on Civil Aerospace Technologies(Grant No.D010203).
文摘The active multi-beam antenna can be widely used in the 6G integrated satellite network project,the national satellite Internet project,and other major satellite projects.It determines the key performance indicators of the satellite such as the service coverage area and the communication capacity of all the beams in the forward link and the return link.The active multi-beam antenna is the core technology of satellite payload and has been developed rapidly in recent years.Based on the antenna performance requirements such as the number of giant-scale beams,super-large coverage area,high gain,and high carrier-to-interference ratio(C/I),this paper proposes a new active multi-beam antenna design method,which integrates the multi-objective coordination and multi-feed amplitude and phase weighted optimization algorithms.A balanced optimal solution that meets the performance requirements can be obtained by constraining each other with different objective functions.In the optimization process,the surrogate model of convolutional autoencoder based on artificial intelligence technology is proposed for multi-objective optimization solution,which efficiently completes the search of optimal beam excitation coefficients.This paper takes the demand for very-high-throughput communication satellites serving the Asia-Pacific region as an example and applies the design method to the multi-beam antenna design of the satellite.The simulation verification of the antenna is completed,achieving good performance of 976 beams.All results meet the performance requirements,supporting the implementation of 1 Tbps communication capacity for the entire satellite,and verifying the correctness of the design method.
