We study on the implementation flow of the radio computerized tomography (RCT) prediction method. A case in real cellular mobile radio (CMR) system together with the prediction results are also presented. As shown by...We study on the implementation flow of the radio computerized tomography (RCT) prediction method. A case in real cellular mobile radio (CMR) system together with the prediction results are also presented. As shown by the results, the RCT prediction method is marked for its convenience and rapidity, as well as its relative high precision even when the prediction procedure is highly simplified. Since it is developed according to the characteristics of wireless communication environments of our country and has concurrently merits from both statistical and deterministic prediction models, the RCT prediction method is in good agreement with engineering practices in cellular mobile communication in cities at home. Optimized by combining with other techniques, further improvement could be achieved in the stability and precision of the RCT prediction method which now serves as the core part of a software tool for commercial use in CMR system analysis and optimization.展开更多
The traditional algorithm for hybrid radar scans uses standard terrain digital elevation model （DEM） data and the latitudes, longitudes and altitudes of contributing radar stations. While radar station location info...The traditional algorithm for hybrid radar scans uses standard terrain digital elevation model （DEM） data and the latitudes, longitudes and altitudes of contributing radar stations. While radar station location information is often inaccurate, signal blockages due to trees, buildings, and other surface objects are not included in the DEM data. Accordingly, hybrid scan elevations derived using this traditional algorithm are prone to errors. Here, reflectivity climatology data （the frequency of occurrence of reflectivity） are used to improve the algorithm for hybrid scans. Three parameters are introduced, then applied to evaluation of signal blockage for every radar bin using a fuzzy logic technique. This new algorithm provides an improved determination of the lowest unblocked elevation for hybrid scans. The new algorithm is validated by exam- ining the scope and continuity of the calculated hybrid scan reflectivity in a case study, and the performance of this climatology-based algorithm is evaluated relative to the traditional terrain-based algorithm. The climatology-based hybrid scans are then used to examine the spatial coverage provided by the operational weather radar network over the Tibetan Plateau. The results indicate that the terrain-based hybrid scan algorithm introduced errors that caused obvious V-shaped gaps in hybrid scan re^ectivity. By contrast, the climatology-based hybrid scan algorithm more accurately determined the lowest unblocked elevation and reduced the impacts of blockage. The coverage map illustrates the limitations of the weather radar network over the Tibetan Plateau. These limitations inhibit the usefulness of the radar data. Additional radar or observational data are needed to fill these gaps and minimize the impacts of signal blockage.展开更多
文摘We study on the implementation flow of the radio computerized tomography (RCT) prediction method. A case in real cellular mobile radio (CMR) system together with the prediction results are also presented. As shown by the results, the RCT prediction method is marked for its convenience and rapidity, as well as its relative high precision even when the prediction procedure is highly simplified. Since it is developed according to the characteristics of wireless communication environments of our country and has concurrently merits from both statistical and deterministic prediction models, the RCT prediction method is in good agreement with engineering practices in cellular mobile communication in cities at home. Optimized by combining with other techniques, further improvement could be achieved in the stability and precision of the RCT prediction method which now serves as the core part of a software tool for commercial use in CMR system analysis and optimization.
基金Supported by the Chinese Academy of Meteorological Sciences Basic Scientific and Operational Project, National Basic Research and Development (973) Program of China (2012CB417202)China Meteorological Administration Special Public Welfare Research Fund (GYHY201006042)
文摘The traditional algorithm for hybrid radar scans uses standard terrain digital elevation model （DEM） data and the latitudes, longitudes and altitudes of contributing radar stations. While radar station location information is often inaccurate, signal blockages due to trees, buildings, and other surface objects are not included in the DEM data. Accordingly, hybrid scan elevations derived using this traditional algorithm are prone to errors. Here, reflectivity climatology data （the frequency of occurrence of reflectivity） are used to improve the algorithm for hybrid scans. Three parameters are introduced, then applied to evaluation of signal blockage for every radar bin using a fuzzy logic technique. This new algorithm provides an improved determination of the lowest unblocked elevation for hybrid scans. The new algorithm is validated by exam- ining the scope and continuity of the calculated hybrid scan reflectivity in a case study, and the performance of this climatology-based algorithm is evaluated relative to the traditional terrain-based algorithm. The climatology-based hybrid scans are then used to examine the spatial coverage provided by the operational weather radar network over the Tibetan Plateau. The results indicate that the terrain-based hybrid scan algorithm introduced errors that caused obvious V-shaped gaps in hybrid scan re^ectivity. By contrast, the climatology-based hybrid scan algorithm more accurately determined the lowest unblocked elevation and reduced the impacts of blockage. The coverage map illustrates the limitations of the weather radar network over the Tibetan Plateau. These limitations inhibit the usefulness of the radar data. Additional radar or observational data are needed to fill these gaps and minimize the impacts of signal blockage.
