3D Positioning via Elevation Angle Estimation
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Solution Overview
Problem
Conventional 3D positioning methods in wireless mobile communication systems, such as OTDOA-based algorithms, require four base stations for accurate positioning, which increases cost and overhead, especially when deploying additional base stations at higher altitudes for better geometrical dilution of precision.
Innovation Solution
A method utilizing three base stations with multiple antennas for beamforming, where user equipment estimates line-of-sight paths and elevation angles from positioning reference signals to calculate its position, reducing the need for a fourth base station and minimizing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four base stations are deployed for 3D positioning, then positioning accuracy is improved, but system cost and overhead increase
Solution Approach 1:
The patent extracts the elevation angle measurement function from the fourth base station requirement. By using multiple antennas at the serving base station to estimate elevation angles through signal processing, the system removes the need for deploying an additional fourth base station, thereby reducing system cost and overhead while maintaining positioning accuracy
Solution Approach 2:
The serving base station with multiple antennas performs multiple functions: it provides both horizontal positioning (through TDOA with two neighboring base stations) and vertical positioning (through elevation angle estimation). This multi-functionality eliminates the need for a dedicated fourth base station, resolving the contradiction between positioning accuracy and system complexity
2Measurement precision
If conventional beamforming scanning is used to determine beam direction, then beam direction accuracy is improved, but time delay and feedback overhead increase
Solution Approach 1:
The system performs preliminary localization to obtain UE position information before beamforming. By first determining the UE's horizontal and vertical positions through TDOA and elevation angle measurements, the base station can directly calculate the optimal beam direction without performing time-consuming scanning operations, thus reducing time delay while maintaining beam direction accuracy
Solution Approach 2:
The UE provides feedback on its estimated position and elevation angle, which the base station uses to directly determine beam direction. This feedback mechanism eliminates the need for iterative scanning and feedback loops, significantly reducing the time delay and feedback overhead associated with conventional beamforming scanning
Data Source
AI summary
A method of accurate 3D positioning with reduced cost is proposed. A user equipment (UE) receives a plurality of positioning reference signals (PRSs) from a plurality of base stations. The plurality of base stations includes a serving base station and two neighboring base stations. The UE estimates a plurality of line-of-sight (LOS) paths and corresponding indexes of the PRSs for time of arrival (TOA) and time difference of arrival (TDOA) measurements. The UE then estimates an elevation angle of the UE based on the estimated LOS paths of the PRS from the serving base station. Finally, the system (either UE or network, depending on where the coordinates are) can calculate the UE position based on the TDOA measurements and the elevation angle.