Positioning Reference Unit Selection for Low-Latency Location Refinement

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Solution Overview

Problem

Existing positioning technologies face challenges in efficiently selecting and activating positioning reference units (PRUs) for accurate and low-latency location estimation of user devices, particularly in terrestrial networks, due to the complexity of associating PRUs with target UEs under varying radio conditions and latency constraints.

Innovation Solution

A method for selecting a subset of positioning reference units based on shared measurement by a common set of network nodes and similar radio conditions with the target user device, using time of flight and timing advance comparisons to refine location estimates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If positioning reference units are selected based on shared measurement by common network nodes and similar radio conditions, then positioning accuracy is improved, but device complexity and selection complexity increase

Engineering Contradiction:
Improvepositioning accuracyVSAvoidPRU selection complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary measurements of reference signals from multiple positioning reference units by common network nodes before the actual positioning process. These pre-measured data including time of flight and timing advance are stored and ready for comparison, eliminating the need for complex real-time measurements when selecting PRUs, thus improving accuracy while managing complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from network node measurements and radio condition comparisons to iteratively select the most suitable PRUs. By continuously monitoring measurement quality and radio condition similarity between target UE and candidate PRUs, the system refines its selection to optimize positioning accuracy without overwhelming complexity.

Inventive Principle:
Principle #23Feedback

2Reliability

If PRUs are selected based on similar radio conditions using time of flight and timing advance comparisons, then positioning reliability is improved, but time consumption for selection increases

Engineering Contradiction:
Improvepositioning reliabilityVSAvoidPRU selection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary measurements and establishes baseline radio condition data for multiple candidate PRUs in advance. By pre-calculating time of flight and timing advance metrics and storing this information, the system reduces the time required during actual positioning operations while maintaining reliable selection based on similar radio conditions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the parameters used for PRU selection by focusing on specific radio condition metrics such as time of flight and timing advance. By monitoring changes in these parameters and selecting PRUs with similar parameter values to the target UE, the system achieves reliable positioning while managing selection time through targeted parameter comparison rather than comprehensive analysis.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a subset of PRUs is selected based on multiple criteria including network node measurements and radio conditions, then positioning accuracy is improved, but the complexity of the selection process increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidselection process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The PRU selection process is segmented into distinct stages: first, network nodes measure reference signals from multiple candidate PRUs; second, measurements are compared against target UE measurements; third, radio conditions are evaluated using time of flight and timing advance; fourth, a subset is selected based on similarity criteria. This segmentation allows complex multi-criteria selection to be managed through systematic, modular processing steps.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system introduces an intermediary selection process that mediates between multiple measurement criteria and the final PRU subset selection. This intermediary layer processes network node measurements, radio condition data, and similarity comparisons to determine the optimal PRU subset, reducing the overall complexity by centralizing the decision-making logic in a dedicated selection mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves positioning accuracy and reduces latency by ensuring PRUs and target UEs experience similar radio conditions, facilitating precise and timely location estimation.

Implementation Method 1

a time of flight of the reference signal transmitted per positioning reference unit of the subset of positioning reference units compared to a time of flight of the reference signal transmitted from the target user device

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP4345487B1Positioning reference unit selection
Publication Date: 2026.03.11 NOKIA SOLUTIONS & NETWORKS OY
  • EP4345487B1 patent drawingFigure 1~2
  • EP4345487B1 patent drawingFigure 3~4
  • EP4345487B1 patent drawingFigure 5

AI summary

Disclosed is a method comprising obtaining a first set of measurement information associated with a reference signal transmitted from a set of positioning reference units; selecting a subset of positioning reference units from the set of positioning reference units, wherein the selection is based at least on determining that the reference signal transmitted per positioning reference unit of the subset of positioning reference units is measured by a same set of network nodes that measured a reference signal transmitted from a target user device; and refining a location estimate of the target user device based at least on a subset of measurement information from the first set of measurement information, wherein the subset of measurement information is associated with the subset of positioning reference units.