NTN Terminal Timing Advance Hold for DMRS Phase Continuity

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Solution Overview

Problem

In non-terrestrial networks (NTN), accurately reporting an appropriate maintained duration for timing advance (TA) is challenging due to varying propagation distance changes caused by the movement of relay stations, terminals, and base stations, which affects power consistency and phase continuity in DMRS bundling.

Innovation Solution

A terminal equipped with a control unit that acquires parameters related to the position or movement of a relay station, terminal, or base station, and reports a duration during which TA updates are not performed to maintain phase continuity, using a reporting mechanism that includes determining and communicating a maximum time duration based on these parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the maintained duration is configured to be long, then the update frequency of TA is reduced, but the phase continuity and power consistency cannot be maintained when propagation distance changes significantly

Engineering Contradiction:
ImproveTA update frequencyVSAvoidphase continuity
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent applies dynamics by making the maintained duration configurable and adaptable rather than fixed. The terminal can report different maintained duration values based on propagation distance changes, allowing the system to dynamically adjust between long durations (for stability) and short durations (for accuracy) depending on the specific NTN scenario and movement characteristics of the relay station and terminal.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the maintained duration is configured to be short, then the phase continuity is maintained, but the TA update frequency increases causing more frequent interruptions

Engineering Contradiction:
Improvephase continuityVSAvoidcommunication efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by allowing the maintained duration parameter to be adjusted based on propagation distance variations. The terminal calculates the appropriate maintained duration considering factors like relay station movement speed, orbital parameters, and current propagation distance, then reports this optimized duration to the base station. This enables the system to use longer maintained durations when propagation distance is stable, improving communication efficiency without sacrificing phase continuity when needed.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the terminal reports maintained duration based on propagation distance, then the accuracy of TA maintenance is improved, but the complexity of calculating and reporting appropriate duration increases

Engineering Contradiction:
Improvemaintained duration accuracyVSAvoidduration calculation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies feedback by establishing a closed-loop mechanism where the terminal monitors propagation distance changes, calculates the appropriate maintained duration, reports it to the base station, and receives acknowledgments or adjustments. The base station can also provide feedback on the reported maintained duration, allowing the terminal to refine its calculations. This feedback loop improves measurement precision while distributing the computational complexity between terminal and base station.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4668994A1terminal
Publication Date: 2025.12.24 NTT DOCOMO INC
  • EP4668994A1 patent drawingFigure 1
  • EP4668994A1 patent drawingFigure 2
  • EP4668994A1 patent drawingFigure 3

AI summary

A terminal includes: a control unit that acquires a parameter related to at least one of a relay station that relays a radio communication between the terminal and a base station, the terminal, and the base station, the parameter related to position or movement; and a transmission unit that reports a duration corresponding to the parameter during which an update of a transmission timing of the terminal in an uplink to cause phase discontinuity is not performed.