Direction of Arrival Estimation Using Non-Uniform Linear Arrays
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Solution Overview
Problem
Existing methods for calculating the direction of arrival for radio and radar signals using non-uniform linear arrays are either too slow, inaccurate, or require significant additional hardware, making them unsuitable for real-time applications that demand speed and precision.
Innovation Solution
A system comprising a non-uniform linear array of antennas and a computing device that processes phase differences to estimate the direction of arrival by calculating phase errors, unwrapping measured phases, and selecting the most likely normalized phase candidate based on likelihood comparisons, allowing for rapid and accurate direction of arrival calculations without requiring extensive hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to calculate direction of arrival, then hardware requirements are minimal, but calculation speed is too slow (greater than one millisecond) and accuracy is insufficient
Solution Approach 1:
The patent segments the direction of arrival calculation into multiple discrete steps: receiving phase differences from antenna pairs, generating normalized phase candidates, calculating phase errors, estimating unwrapped measured phases, and calculating likelihoods. This segmentation allows each step to be optimized independently and processed efficiently in sequence, reducing overall calculation time while maintaining accuracy
Solution Approach 2:
The patent performs preliminary actions by pre-calculating and storing normalized phase candidates before actual direction of arrival measurement. The system generates a set of possible normalized phase values in advance, which are then evaluated against received phase differences. This preliminary preparation significantly speeds up the real-time calculation process by eliminating the need for complex iterative computations during actual measurement
2Productivity
If calculation speed is increased to meet real-time requirements, then processing time is reduced, but accuracy and reliability of direction of arrival estimation deteriorate
Solution Approach 1:
The patent implements feedback through the likelihood calculation step, where each normalized phase candidate is evaluated based on how well it explains the received phase differences. The system calculates a likelihood value for each candidate and uses this feedback to select the most probable direction of arrival. This feedback mechanism ensures that speed optimizations do not compromise reliability, as the final selection is guided by statistical evidence from the measurements
Solution Approach 2:
The patent changes parameters by working with normalized phase candidates rather than directly computing direction angles. The system transforms the problem into evaluating discrete normalized phase values, calculating phase errors, and determining likelihoods. This parameter transformation allows for faster computation while maintaining estimation reliability through the structured evaluation framework
3Adaptability or versatility
If uniform linear arrays are used, then hardware configuration is simple, but the system cannot effectively handle multiple signals from multiple sources simultaneously
Solution Approach 1:
The patent achieves universality by developing a direction of arrival estimation method that works with non-uniform linear arrays and can simultaneously process multiple signals from different sources. The same algorithmic framework handles phase differences from multiple antenna pairs and multiple signal sources without requiring separate processing systems, making the hardware configuration versatile for various multi-signal scenarios
Solution Approach 2:
The patent embraces asymmetry by utilizing non-uniform spacing between antenna elements in the linear array. Rather than requiring uniform spacing, the system is designed to work with asymmetric antenna positions, which actually improves the ability to resolve multiple signals from different directions. The algorithm compensates for the asymmetric geometry through its phase difference processing and likelihood evaluation approach
Data Source
AI summary
A system for determining a direction of arrival for signals is provided. The system includes a non-uniform linear array including a plurality of antenna and configured to receive a wireless signal. The system is programmed to receive a plurality of normalized phase candidates for the direction of arrival of the received wireless signal. For each of the plurality of normalized phase candidates, the at least one processor is programmed to calculate a phase error, estimate a plurality of unwrapped measured phases based on the corresponding phase error, and calculate a likelihood based on the corresponding plurality of unwrapped measured phases. The at least one processor is further programmed to select a normalized phase candidate as a direction of arrival estimate based on a comparison of the plurality of likelihood normalized phases.