PRS Power Pattern for Wireless Location Accuracy

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Solution Overview

Problem

Existing wireless communication systems face challenges in accurately determining the geographic location of user equipment (UE) due to interference and signal obfuscation, which affects the accuracy of positioning reference signals (PRS) and leads to incorrect location estimates.

Innovation Solution

Implementing a PRS transmission power pattern for each cell, allowing for a series of transmission power level values that minimize interference while ensuring PRSs are available for UEs not experiencing issues, by selecting power levels from a non-binary set of allowable transmission powers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If PRS transmission power is increased to improve signal quality and location accuracy, then measurement precision improves, but interference from concurrent transmissions increases

Engineering Contradiction:
ImprovePRS measurement accuracyVSAvoidinterference from concurrent transmissions
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent implements periodic muting of PRS transmissions according to a muting pattern, where certain PRS transmission occasions are muted while others are transmitted at full power. This periodic action reduces interference from concurrent transmissions while maintaining measurement accuracy by ensuring PRSs are available during non-muted occasions.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes the transmission power parameter dynamically by selecting from a set of allowable transmission power values, including zero power for muted occasions. This parameter change allows the system to adjust between full power transmission for accuracy and zero power for interference reduction.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If PRS transmission is muted according to a periodic pattern to reduce interference, then interference with neighbor cells decreases, but PRS availability for UEs experiencing no interference issues also decreases

Engineering Contradiction:
Improveinterference with neighbor cellsVSAvoidPRS availability for UEs
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent applies periodic muting patterns that selectively mute certain PRS transmission occasions while leaving others active. This ensures that UEs not experiencing interference can still receive PRSs during non-muted occasions, maintaining reliability while reducing interference during muted occasions.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies different transmission qualities (muted vs. full power) to different PRS transmission occasions based on local interference conditions. This allows the system to reduce interference where needed while maintaining full PRS availability where interference is not an issue.

Inventive Principle:
Principle #3Local quality

3Device complexity

If cells share the same Physical Cell Identity (PCI) to simplify cell identification, then device complexity decreases, but the ability to correctly identify source cells deteriorates when PRSs are blocked

Engineering Contradiction:
Improvecell identification complexityVSAvoidsource cell identification accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces transmission power pattern information as an intermediary identifier that works alongside PCI. When PRSs are blocked and PCI alone is insufficient for identification, the transmission power pattern serves as an additional distinguishing characteristic to correctly identify the source cell.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates asymmetry in the identification system by combining the symmetric PCI identification with asymmetric transmission power patterns. This allows cells with the same PCI to be distinguished through their unique power transmission characteristics.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP3583806B1PRS power pattern
Publication Date: 2021.07.07 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3583806B1 patent drawingFigure 1
  • EP3583806B1 patent drawingFigure 2
  • EP3583806B1 patent drawingFigure 3

AI summary

Methods and apparatus for estimating a location of a user equipment (UE) (102) in a wireless communication system (100) are presented. For instance, in an example method performed by a UE (102), the UE (102) can receive positioning reference signals (PRSs) transmitted by multiple cells, where a cell of the multiple cells transmits a series of PRSs according to a transmission power pattern (112). The transmission power pattern (112) defines a transmission power for each PRS of the series, the transmission power for each PRS of the series being part of a non-binary set of allowable transmission powers. The example method may also include generating PRS measurement data (114) for the UE (102) based on the received PRSs. Methods and apparatuses related to the UE example above are provided for a positioning server (108) and network node (106).