LTE Positioning Measurement Using PCI and Time Alignment
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Solution Overview
Problem
In the LTE-Advanced wireless communications system, the insufficient number of unique physical cell identities (PCIs) causes confusion in UE positioning measurement, and unclear specifications lead to inaccuracies due to RS interference, unsynchronized cells, and missing assistance data for cell identification.
Innovation Solution
The method enhances positioning measurement by including additional cell identifications and time alignment information in assistance data, allowing the UE to distinguish cells with the same PCI and accurately report measured cells, and determining transmission patterns to avoid confusion and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple cells share the same PCI to increase system capacity, then the number of available cells increases, but PCI confusion occurs causing positioning measurement inaccuracies
Solution Approach 1:
The patent segments the cell identification process into multiple independent identification methods: PCI-based identification, time alignment information-based identification, and reference signal arrival time-based identification. This segmentation allows the system to distinguish between cells with the same PCI by using alternative identification mechanisms, thereby resolving the PCI confusion problem while maintaining the ability to support multiple cells.
Solution Approach 2:
The patent introduces time alignment information as an intermediary element between the PCI and the cell. When multiple cells share the same PCI, the time alignment information serves as a mediator to differentiate these cells. The network provides time alignment information corresponding to each cell's reference signal transmission timing, allowing the UE to identify which cell a measured PCI belongs to based on the matching time alignment characteristics.
2Ease of operation
If the network provides assistance data with PCIs for positioning measurement, then positioning measurement can be performed, but PCI confusion prevents the network from identifying which cell was measured
Solution Approach 1:
The patent implements a feedback mechanism where the UE measures reference signals from cells identified by PCIs, then reports both the PCI and the corresponding time alignment information to the network. The network uses this feedback to verify which cell the UE actually measured by comparing the reported time alignment information with the stored time alignment information for each cell. This feedback loop ensures accurate cell identification even when multiple cells share the same PCI.
Solution Approach 2:
The patent changes the parameter set used for cell identification from solely PCI to a combination of PCI and time alignment information. By adding time alignment information as an additional identification parameter, the system can uniquely identify cells even when PCI values are duplicated. The network configures assistance data including both PCI and corresponding time alignment information, and the UE uses both parameters to identify and report measured cells.
3Measurement precision
If reference signals are transmitted from multiple cells for positioning measurement, then positioning accuracy can be improved, but RS interference from unsynchronized cells degrades measurement quality
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure time alignment information for each cell before the UE performs positioning measurement. The network provides assistance data that includes time alignment information corresponding to each cell's reference signal transmission timing. This preliminary configuration allows the UE to anticipate the timing characteristics of reference signals from different cells, enabling the UE to distinguish between desired reference signals and interfering signals from unsynchronized cells based on their timing patterns.
Data Source
AI summary
A method of enhancing positioning measurement for a network in a wireless communications system is disclosed. The method comprises including a plurality of identifications of a plurality of cells associated with the positioning measurement of a mobile device of the wireless communications system in assistance data, whereby the plurality of cells are identified according to the plurality of identifications.