Beam Control Method for Reducing Side Lobe Interference
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Solution Overview
Problem
Conventional methods for reducing side lobe output in array antennas, such as the bat algorithm, often get stuck in local minima, making it difficult to obtain the optimum weighting for minimizing side lobe interference.
Innovation Solution
A wireless communication apparatus and method that derive a weighting vector corresponding to the maximum eigenvalue of a matrix obtained by subtracting the side lobe output power matrix from the main lobe output power matrix, adjusted by a reduction ratio, to determine an optimal power ratio for minimizing side lobe interference with the main lobe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an iterative operation method such as the bat algorithm is employed to optimize beam weighting, then the method can adjust gain and phase of antenna elements, but it is difficult to avoid getting stuck in local minima and cannot always obtain the optimum value for reducing side lobe output
Solution Approach 1:
The patent replaces the iterative mechanical optimization process (bat algorithm) with a direct mathematical solution using eigenvalue decomposition. Instead of iteratively adjusting weights through trial and error, the system computes the optimal weighting vector by solving the eigenvalue problem of the covariance matrix, directly obtaining the global optimum without getting stuck in local minima.
Solution Approach 2:
The patent transforms the optimization problem from an iterative parameter adjustment approach to a closed-form mathematical solution. By changing the problem formulation to use eigenvalue decomposition of the covariance matrix, the system directly determines optimal weights based on the maximum eigenvalue and corresponding eigenvector, eliminating the need for iterative search and ensuring reliable convergence to the global optimum.
2Object-generated harmful factors
If the output of side lobe in a particular direction is reduced using conventional methods, then interference in that direction decreases, but the methods cannot guarantee optimal reduction across all directions due to local minimum trapping
Solution Approach 1:
The patent employs feedback through the covariance matrix computation, which captures the actual interference patterns from multiple beams. The eigenvalue decomposition process uses this feedback information to automatically determine the optimal weighting that maximizes the main lobe output while suppressing side lobes, achieving precise control without requiring manual tuning or iterative adjustment.
Solution Approach 2:
The patent performs preliminary computation of the covariance matrix and its eigenvalue decomposition before actual beam transmission. This preliminary action pre-determines the optimal weighting vector that will achieve maximum side lobe suppression, eliminating the need for iterative refinement during operation and ensuring precise control from the start.
3Reliability
If eigenvalue-based weighting vector derivation is used, then the optimum value for reducing side lobe output can be positively obtained, but the computational process requires matrix operations and eigenvalue decomposition
Solution Approach 1:
The patent segments the beamforming optimization problem into distinct computational stages: (1) computing the covariance matrix from received beam signals, (2) performing eigenvalue decomposition to extract the maximum eigenvalue and eigenvector, and (3) applying the derived weighting vector to the antenna elements. This segmentation makes the complex computation manageable and implementable in practical wireless communication systems.
Data Source
AI summary
A wireless communication apparatus outputs first and second beams, based on a weighting vector representing gain and/or phase weighting. The apparatus derives a weighting vector corresponding to a maximum eigen value of a matrix obtained by subtracting, from a first matrix representing a main lobe output power of the first beam, a matrix obtained by multiplying a second matrix representing a side lobe output power of the first beam to a reduction ratio for reducing the side lobe output power of the first beam interfering with a main lobe of the second beam. The apparatus determines whether or not a power ratio of the main lobe output power of the first beam with respect to the side lobe output power of the first beam is greater than a maximum SIRmax, and extracts the weighting vector when the power ratio is not larger than the maximum SIRmax.