Incoming Wave Estimation Using Frequency-Selective Singular Values
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Solution Overview
Problem
Existing direction-of-arrival estimation methods, such as the MUSIC method, struggle to accurately distinguish incoming waves from objects with low Radar Cross-Section (RCS) due to low signal power, leading to reduced accuracy in estimating the number of incoming waves.
Innovation Solution
A communication apparatus and method that utilizes a plurality of antennas to calculate and process reception signals through singular value decomposition, extracting signals within a specific frequency range, and estimating the number of incoming waves based on singular value ratios or eigenvalue ratios, reducing the impact of signal power and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform threshold is used for normalized eigenvalues to estimate the number of incoming waves, then the estimation method is simple and does not depend on RCS, but the accuracy of estimation decreases for objects with small RCS because incoming waves and noise cannot be distinguished
Solution Approach 1:
The patent segments the reception signal matrix into multiple sub-matrices based on different time periods or frequency bands. By dividing the original estimation problem into multiple sub-problems, the method can identify incoming waves more reliably even when their power is low, as each sub-matrix provides additional independent information for distinction from noise.
Solution Approach 2:
The patent transforms the estimation approach by introducing a new dimension through singular value decomposition and eigenvalue analysis of multiple sub-matrices. Instead of relying solely on power-based thresholding in the time domain, the method utilizes the spectral dimension and matrix structure to distinguish incoming waves from noise, enabling accurate detection of low-RCS objects.
2Ease of operation
If correlation is reduced in the reception signal, then processing becomes easier, but the electric power of reception signals for small RCS objects remains small making distinction from noise difficult
Solution Approach 1:
The patent performs preliminary processing by calculating correlation matrices and performing singular value decomposition on reception signals before final estimation. This preliminary action of decomposing the signal structure into eigenvalues and eigenvectors prepares the data in a form that enhances the distinguishability of weak incoming waves from noise while maintaining processing efficiency.
Solution Approach 2:
The patent introduces eigenvalues and eigenvectors as intermediary elements that mediate between the raw reception signals and the final incoming wave estimation. These intermediaries transform the signal representation into a domain where the distinction between incoming waves and noise is more pronounced, thereby improving reliability without requiring increased signal power.
Data Source
AI summary
A communication apparatus capable of estimating the number of incoming waves with high accuracy is provided. A communication apparatus includes an antenna, a matrix calculator that calculates, based on reception signals received from the antenna, a first matrix having singular values of a reception signal matrix, a matrix calculator that extracts reception signals whose frequency is within a specific frequency range from the reception signals and calculates, based on the extracted reception signals, a second matrix having singular values of a second reception signal matrix, and a number-of-incoming-waves estimator that estimates, based on the first matrix and the second matrix, the number of incoming waves of the reception signals.