Satellite Beam Weighting for Co-Channel Interference Suppression
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Solution Overview
Problem
Current satellite communication systems face significant challenges in efficiently suppressing co-channel interference, particularly in systems with increasing user numbers and bit-rates, where frequency reuse leads to signal degradation due to sidelobe interference, and increasing antenna size is costly and inefficient.
Innovation Solution
The method involves digitizing antenna element signals, processing them to separate frequency channels, calculating complex weighting values using algorithms like the Constant Modulus Algorithm, and adjusting beam signals to cancel interference, thereby minimizing co-channel interference while maintaining main lobe gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antenna size is increased to reduce sidelobes and co-channel interference, then interference suppression improves, but system cost and resource requirements increase
Solution Approach 1:
The patent changes the parameters of beam signals by calculating complex weighting values that adjust amplitude and phase characteristics. This digital signal processing approach modifies beam formation parameters to suppress sidelobes and reduce co-channel interference without physically enlarging the antenna structure.
Solution Approach 2:
The patent replaces the mechanical approach of increasing antenna size with a digital signal processing system. By using complex weighting calculations and digital beam forming, the system achieves interference suppression through electronic/algorithmic means rather than mechanical structural changes.
2Productivity
If frequency reuse is maximized to increase system capacity, then bandwidth efficiency improves, but co-channel interference increases
Solution Approach 1:
The patent applies different complex weighting values to different beam signals locally. Each beam receives customized weighting that optimizes its specific interference environment, allowing frequency reuse across multiple beams while suppressing local co-channel interference through localized beam signal adjustment.
Solution Approach 2:
The system dynamically changes beam signal parameters (complex weights) based on interference conditions. This allows multiple frequency channels to be reused simultaneously by adapting each beam's characteristics to minimize interference while maintaining system capacity.
3Productivity
If digital beam forming is used to control spot beam parameters, then frequency reuse efficiency improves, but device complexity increases
Solution Approach 1:
The patent segments the signal processing into distinct stages: digitization of antenna element signals, separation of frequency channels, calculation of complex weighting values, and application of weights to beam signals. This segmentation manages complexity by breaking down the overall processing task into manageable modular steps.
Solution Approach 2:
The system uses received signal components to calculate complex weighting values that are then applied to beam signals. This feedback loop allows the system to adapt beam parameters based on actual received signals, improving frequency reuse efficiency through dynamic adjustment while managing complexity through iterative processing.
Data Source
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AI summary
The invention relates to active interference suppression in a satellite communication system, particularly but not exclusively to an apparatus and method for using active interference suppression in order to suppress co-channel interference between user signals in the communication system. The communication system includes a receive or transmit antenna having a plurality of antenna elements, each antenna element associated with a respective antenna element signal. The method includes the steps of calculating complex weighting values for one or more of a plurality of beam signals, adjusting the beam signals in accordance with the calculated complex weighting values and cancelling co-channel interference in at least one of the beam signals using the one or more adjusted derived beam signals to provide an interference suppressed output signal. The complex weighting values can be calculated based on a constant modulus algorithm.