LTE Assistance Data Frame Offset for RSTD Reference Cell Selection
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Solution Overview
Problem
The existing OTDOA-based location determination methods face limitations in precision and reliability due to the inability to perform RSTD measurements when the assistance data reference cell is not the serving cell, leading to incomplete frame timing information and reduced flexibility in selecting the RSTD reference cell, which can result in failed or degraded positioning operations.
Innovation Solution
Incorporating frame number offset information into the assistance data provided by the location server to the user equipment, allowing it to determine the frame timing of neighboring cells relative to the assistance data reference cell, thereby enabling RSTD measurements even when the serving cell does not have PRS configured and allowing flexible selection of the RSTD reference cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the assistance data reference cell is not the serving cell, then the flexibility in selecting RSTD reference cell is improved, but the ability to perform RSTD measurements deteriorates due to incomplete frame timing information
Solution Approach 1:
The location server pre-calculates and provides frame number offset information in the assistance data before the UE needs to perform measurements. This preliminary provision of timing information enables the UE to successfully perform RSTD measurements even when the reference cell is not the serving cell, resolving the contradiction between flexibility and measurement reliability
2Measurement precision
If frame number offset information is provided in assistance data, then the precision of RSTD measurements is improved, but the complexity of assistance data increases
Solution Approach 1:
The invention introduces a specific parameter (frame number offset) that quantifies the timing relationship between cells. By changing the assistance data structure to include this parameter, the system enables precise RSTD measurements while maintaining a relatively simple and structured data format that follows existing LTE assistance data conventions
3Adaptability or versatility
If the serving cell does not have PRS configured, then the adaptability of the positioning system is improved, but the reliability of PRS-based measurements deteriorates
Solution Approach 1:
The frame number offset information acts as an intermediary that bridges the timing relationship between the serving cell and neighboring cells. This intermediary information enables the UE to perform PRS-based measurements on neighboring cells even when the serving cell lacks PRS configuration, maintaining measurement reliability while improving system adaptability
Data Source
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AI summary
A device for use in a mobile communication user equipment, UE, includes processing circuitry to: receive cell data pertaining to a plurality of assistance data cells, and receive offset information, wherein the offset information describes respective LTE frame offsets between an assistance data reference cell and each of a plurality of neighbour cells. A location server to provide positioning assistance data to a user equipment, UE, comprises processing circuitry to: determine offset information describing respective LTE frame time offsets between an assistance data reference cell and each of a plurality of neighbour cells.