OTDOA Positioning in LAA Unlicensed Spectrum
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Solution Overview
Problem
Positioning accuracy in wireless communication systems using unlicensed spectrum is hindered by the unpredictable and less coordinated signal transmissions from small cell access points, which impede the use of small cells for accurate location determination, especially in 5G networks where high data rates and numerous connections are required.
Innovation Solution
A method where a UE receives positioning assistance data with multiple PRS configurations for secondary cells with overlapping coverage areas, measures PRS signals at specific occasions, and sends these measurements to a location server to determine its position, optimizing positioning by coordinating PRS transmissions across secondary cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If small cell access points transmit PRS signals in unlicensed spectrum, then positioning coverage is extended, but positioning accuracy deteriorates due to unpredictable and less coordinated signal transmissions
Solution Approach 1:
The network configures multiple secondary cells with different PRS configurations in advance, including different positioning occasions, resource sets, and signal parameters. This preliminary configuration enables the UE to measure PRS from multiple cells at different times, overcoming the unpredictability of unlicensed spectrum transmissions while maintaining positioning accuracy
Solution Approach 2:
Different secondary cells are assigned different PRS configuration parameters including distinct positioning occasions, resource sets, and signal characteristics. This parameter differentiation allows the UE to distinguish and measure PRS from multiple cells independently, resolving the coordination problem in unlicensed spectrum and improving positioning accuracy
2Reliability
If multiple secondary cells with overlapping coverage transmit PRS signals simultaneously, then positioning reliability is improved, but signal coordination deteriorates leading to measurement conflicts
Solution Approach 1:
The network performs preliminary configuration of multiple secondary cells with distinct PRS positioning occasions and resource sets before positioning measurements. This advance configuration ensures that cells with overlapping coverage do not transmit PRS simultaneously, preventing measurement conflicts while maintaining positioning reliability through multiple measurement opportunities
Solution Approach 2:
PRS transmissions from multiple secondary cells are segmented into different time occasions and resource sets. By dividing the PRS transmission resources across multiple cells with non-overlapping time-frequency resources, the system maintains signal coordination stability while preserving the reliability benefits of multiple cell measurements
Data Source
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AI summary
Disclosed are techniques for determining a location of a user equipment (UE) communicating over a shared communication medium in unlicensed spectrum. In an aspect, the UE receives a unique or distinct positioning reference signal (PRS) configuration for each of a plurality of secondary cells, where each PRS configuration includes a common set of positioning occasions and where the plurality of secondary cells are in contention for the common set of positioning occasions. The UE attempts to measure a PRS for each of the PRS configurations in each positioning occasion and typically measures a PRS for just one PRS configuration in each positioning occasion due to the contention for positioning occasions. The UE reports the PRS measurements and the identities of the measured PRS configurations to a location server which uses the reported data to determine a location for the UE.