Terminal Uplink Timing Offsets for Reliable NTN RACH Fallback

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Solution Overview

Problem

Existing wireless communication systems face challenges in determining the optimal transmission timing of uplink signals related to the Random Access Channel (RACH) in non-terrestrial networks (NTN), ensuring reliable fall-back operations for terminals.

Innovation Solution

A method for transmitting uplink signals in a wireless communication system supporting NTN, involving the reception of system information for configuring a first K offset, and a control signal for updating a second K offset based on the first K offset, allowing the uplink signal to be transmitted based on either the first or second K offset, ensuring reliable RACH procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a terminal uses a cell-specific K offset for RACH-related uplink signals, then fall-back operation reliability is ensured, but transmission timing flexibility is reduced

Engineering Contradiction:

Improvefall-back operation reliabilityVSAvoidtransmission timing flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic K offset mechanism where the terminal can switch between cell-specific K offset (for RACH fallback reliability) and terminal-specific K offset (for transmission timing flexibility). The terminal determines whether to apply the cell-specific or terminal-specific K offset based on the signal type, enabling adaptive timing adjustment while ensuring fallback operation reliability for RACH signals.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If a terminal-specific K offset is configured and updated via MAC-CE, then transmission timing precision is improved, but signaling overhead increases

Engineering Contradiction:

Improvetransmission timing precisionVSAvoidsignaling overhead

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent applies different K offset configurations to different signal types: terminal-specific K offset (with MAC-CE updates) is applied to non-RACH uplink signals requiring precise timing, while cell-specific K offset is used for RACH signals. This selective application reduces unnecessary signaling overhead for RACH operations while maintaining timing precision for other signals.

Inventive Principle:

Principle #3Local quality

3Speed

If K offset updates are applied immediately upon receiving MAC-CE, then transmission timing responsiveness is improved, but timing synchronization accuracy deteriorates

Engineering Contradiction:

Improvetransmission timing responsivenessVSAvoidtiming synchronization accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The patent introduces a predetermined time offset between MAC-CE reception and K offset application. The terminal receives the MAC-CE update, waits for the predetermined time duration, and then applies the updated K offset. This preliminary waiting period allows the base station to account for propagation delay, ensuring timing synchronization accuracy is maintained while still achieving responsive updates.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12349090B2Method for transmitting uplink signal by terminal in wireless communication system, and apparatus therefor

Publication Date: 2025.07.01 LG ELECTRONICS INC

AI summary

Disclosed are a method and an apparatus for transmitting an uplink signal by a terminal in a wireless communication system supporting a non-terrestrial network (NTN) according to various embodiments. The method includes receiving system information for configuring a first K offset, receiving a control signal for configuring or updating a second K offset based on the first K offset, and transmitting the uplink signal based on the first K offset or the second K offset, wherein, based on the uplink signal being related to a random access channel (RACH), the uplink signal is transmitted based on the first K offset.