RAT-Dependent Positioning Assistance Data for Idle-Mode UE
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Solution Overview
Problem
Challenges exist in specifying system level aspects of downlink (DL)-only user equipment (UE) based positioning, particularly in supporting RAT-dependent procedures such as DL OTDOA, which have not been adequately addressed in UE-based scenarios, and there is a lack of support for UE-based DL OTDOA in existing LTE standards, requiring the UE to be in RRC connected mode for periodic reporting.
Innovation Solution
A method for UE-based RAT-dependent positioning is introduced, where a wireless device receives assistance data based on device-specific information, including cell-specific details such as identity, location, and real-time differences, tailored to the device's subscription, capabilities, and positioning requirements, enabling positioning in idle or inactive modes through configuration signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE is required to be in RRC connected mode for periodic positioning reports, then positioning accuracy can be maintained through network assistance, but device power consumption increases and positioning availability decreases when UE is in idle mode
Solution Approach 1:
The UE performs autonomous positioning calculations using assistance data received during RRC connected mode. The device independently computes its position based on reference signal measurements and provided assistance information, then stores results for later reporting when in idle mode, eliminating the need for continuous network connection
Solution Approach 2:
The network provides assistance data (including cell information, reference signal configurations, and positioning parameters) to the UE during RRC connected mode before the UE transitions to idle mode. The UE prepares positioning results in advance and stores them for subsequent reporting, enabling positioning functionality without maintaining continuous connection
2Measurement precision
If assistance data is provided for all cells, then positioning accuracy is maximized, but data transmission overhead and network resource consumption increase
Solution Approach 1:
The network identifies and provides assistance data only for cells that are relevant to the specific UE's location and positioning requirements. The assistance data includes cell-specific information (physical cell IDs, reference signal configurations, timing advance values) tailored to the UE's serving cell and neighboring cells, rather than broadcasting all cell information network-wide
Solution Approach 2:
The assistance data is segmented into UE-specific portions containing only the necessary cell information for that particular device's positioning needs. The network divides the comprehensive cell database into targeted subsets based on UE location, subscription information, and service requirements, reducing overall data transmission while maintaining positioning accuracy
Data Source
AI summary
A wireless device (12) is configured for radio access technology, RAT, dependent positioning in a wireless communication network (10). The wireless device (12) receives, from a network node (18), assistance data (20) that assists the wireless device (12) with RAT-dependent positioning, e.g., downlink Observed Time Difference of Arrival. The assistance data (20) may be based on device-specific information. The device-specific information may for example include a subscription associated with the wireless device (12). The wireless device (12) may perform the RAT-dependent positioning based on assistance from the assistance data (20).