Multibeam Satellite Frequency Reuse via Zone Segmentation
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Solution Overview
Problem
Current high-capacity broadband satellite communication systems face limitations in increasing capacity density without reducing the signal-to-interference ratio (C/I) in forward channels, especially when using fractional or full frequency reuse schemes.
Innovation Solution
A broadband multibeam satellite radiocommunication system is configured with a multibeam transmission antenna system that allocates a main frequency band to central internal zones and secondary sub-bands to peripheral zones, utilizing quadruple points of intersection to define elementary coverage areas, thereby optimizing frequency reuse and polarization allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of colors in frequency reuse is reduced to increase spectral efficiency, then the band reuse factor improves, but the C/I ratio deteriorates due to decreased distance between spots of the same color
Solution Approach 1:
The frequency band is segmented into a main band BP allocated to central internal zones and secondary sub-bands BS allocated to peripheral zones. This segmentation allows different frequency resources to be assigned to different spatial regions, enabling reduced color numbers while maintaining C/I ratios through spatial-frequency resource mapping.
Solution Approach 2:
Different frequency resources are assigned to different spatial locations: the main band BP is allocated to central internal zones where high C/I is required, while secondary sub-bands BS are allocated to peripheral zones. This local differentiation of frequency resources allows the system to achieve both high spectral efficiency and adequate C/I performance in different regions.
2Productivity
If the surface of the internal zone of each emission spot is increased to improve capacity density, then the system capacity increases, but the C/I ratio deteriorates due to increased interference from adjacent spots
Solution Approach 1:
The frequency band is divided into main band BP for central zones and secondary sub-bands BS for peripheral zones. By allocating different frequency resources to different spatial zones, the system can expand internal zone surfaces to improve capacity density while preventing interference through frequency separation.
Solution Approach 2:
The patent introduces a frequency dimension to resolve spatial interference. By allocating different frequency bands (main band vs. secondary sub-bands) to different spatial zones (central vs. peripheral), the system transforms a two-dimensional spatial problem into a three-dimensional space-frequency resource allocation problem, enabling larger internal zones without C/I degradation.
3Productivity
If fractional frequency reuse is implemented to increase bandwidth per spot, then the spectral efficiency improves, but the complexity of frequency allocation and resource management increases
Solution Approach 1:
The frequency band is segmented into main band BP and secondary sub-bands BS with distinct allocation rules. This segmentation simplifies resource management by creating clear allocation zones: central zones receive main band resources while peripheral zones receive secondary sub-band resources, reducing the complexity of fractional frequency reuse implementation.
Data Source
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AI summary
A broadband multibeam satellite radio communications system is configured to cover a geographical service area (22), decomposed into a plurality of transmit spots (26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50), each consisting of a central internal zone (106, 108, 110, 112, 114, 116, 118) and a peripheral zone (126, 128, 130, 132, 134, 136, 138). A first polarization state and a second polarization state are allocated respectively to the spots of a first grid G1 and to the spots of the second grid G2; the same main frequency band BP is allocated in its entirety to each central internal zone. The coverage of the quadruple point service area is a tiling of elementary useful surfaces or cover meshes having the shape of a parallelogram.