UE Positioning via Timing Range Screening
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Solution Overview
Problem
Existing methods for accurately positioning wireless user equipment (UE) face challenges due to hearability and multipath issues, which affect the accuracy of observed time difference of arrival (OTDOA) measurements, particularly in meeting the FCC's E911 requirements for LTE-based wireless calls.
Innovation Solution
The method involves receiving reference signals from multiple target neighbor cells, estimating a timing range using timing advance and inter-cell distance, computing reference signal time differences, and screening these values to eliminate outliers, thereby improving positioning accuracy through trilateration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OTDOA method is used for positioning UE, then positioning capability is provided, but positioning accuracy deteriorates due to hearability and multipath issues
Solution Approach 1:
The system pre-calculates and stores timing advance values and inter-cell distances before positioning measurements are performed. These preliminary calculations establish expected timing ranges that are used to validate and screen the measured reference signal time differences, eliminating the need for real-time complex calculations and enabling rapid identification of valid measurements.
Solution Approach 2:
The patent introduces timing range as an intermediary parameter that mediates between the raw OTDOA measurements and the final positioning calculation. By comparing measured RSTD values against the pre-calculated timing ranges, the system acts as a filter to eliminate multipath distortions and hearability issues, allowing only valid measurements to contribute to the positioning result.
2Measurement precision
If timing range screening is applied to eliminate outliers, then positioning accuracy is improved, but computational complexity increases
Solution Approach 1:
The system performs the computationally intensive timing range calculations in advance, storing the results for later use. This preliminary action shifts the computational burden from the real-time positioning measurement phase to an offline preparation phase, significantly reducing the complexity of real-time operations while maintaining accurate screening capability.
Solution Approach 2:
The patent calculates timing ranges for all possible neighbor cells in advance, even though not all cells will be visible or relevant at any given moment. This excessive calculation ensures that when a positioning measurement occurs, the screening process can immediately use pre-computed values without requiring complex real-time calculations, trading some offline computational effort for minimal online complexity.
Data Source
AI summary
In accordance with an example embodiment of the present invention, a method is disclosed that comprises receiving a reference signal from each of at least two target neighbor cells via at least one receiving branch at a user equipment; estimating a timing range based at least on one of a timing advance for a serving cell and an inter-cell distance between the target neighbor cell and the serving cell; computing a reference signal time difference for the received reference signal from the target neighbor cell; and screening the computed reference signal time difference using the estimated timing range.