UE Positioning via Phase Difference Ambiguity Resolution
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Solution Overview
Problem
Current positioning methods using wireless signals face challenges in achieving high precision due to integer ambiguity issues, particularly when trying to determine the phase difference with shorter wavelengths, which affects the accuracy of user equipment (UE) positioning.
Innovation Solution
The method involves receiving reference signals from multiple base stations, calculating phase differences based on subcarrier wavelengths, and iteratively estimating coordinates and integer ambiguities using a processor to improve positioning precision by modifying initial estimates through partial differential coefficients and discrete Fourier transform operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wavelength of the reference signal is reduced to improve positioning precision, then the positioning precision for phase or phase difference is improved, but the period of the phase value or phase difference becomes ambiguous making it difficult to determine integer ambiguity
Solution Approach 1:
The patent segments the positioning process into multiple stages: first obtaining a rough position estimate using a longer wavelength signal, then using this estimate to resolve integer ambiguity for a shorter wavelength signal to achieve high precision positioning. This segmentation allows each stage to use optimal wavelengths for their specific purposes without the drawbacks affecting the other stage.
Solution Approach 2:
The patent performs preliminary positioning using a longer wavelength reference signal before using the shorter wavelength signal for final high-precision positioning. The preliminary position estimate obtained from the longer wavelength signal is used to determine the integer ambiguity of the shorter wavelength signal, enabling the system to overcome the ambiguity problem that would otherwise prevent high-precision positioning.
2Measurement precision
If iterative calculations are performed to improve positioning accuracy, then the positioning precision is improved, but the calculation complexity and processing time increase
Solution Approach 1:
The patent performs preliminary calculations using longer wavelength signals to obtain initial position estimates and resolve integer ambiguities before conducting iterative refinements with shorter wavelength signals. This preliminary action reduces the search space for iterative optimization, making the subsequent iterative calculations more efficient and less complex.
Solution Approach 2:
The patent implements feedback mechanisms where the position estimates from iterative calculations are continuously refined by comparing with expected values and adjusting the integer ambiguity selections. The feedback loop uses the difference between calculated and expected positions to guide the optimization process, improving accuracy while maintaining manageable complexity through directed search rather than exhaustive enumeration.
Data Source
AI summary
Provided is a positioning method performed by a user equipment (UE). The positioning method includes receiving reference signals from a plurality of base stations; acquiring phase difference information depending on a wavelength of at least one subcarrier among subcarriers included in the reference signals; calculating first estimated coordinates of the UE based on first phase difference information depending on a wavelength of a first subcarrier among the subcarriers; and calculating a first travel distance difference between the reference signals from the first estimated coordinates and estimating integer ambiguity of a second phase difference depending on a wavelength of a second subcarrier from the first travel distance difference.