Sidelink Clock Reference Selection Outside 5G Coverage

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Solution Overview

Problem

Current 5G mobile communication networks struggle with clock synchronization outside the coverage area of access network devices, preventing UEs from maintaining synchronization with the network.

Innovation Solution

UEs outside network coverage can receive clock synchronization information via sidelink from synchronized terminal devices, using priority-based selection mechanisms to determine reference sources, including satellite and access network devices, and adjust for propagation delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If clock synchronization is implemented only through access network device coverage, then synchronization accuracy within coverage is maintained, but coverage area and accessibility are limited

Engineering Contradiction:
Improvecoverage areaVSAvoidsynchronization reliability
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces terminal devices as intermediary nodes that can forward clock synchronization information via sidelink to other terminal devices outside network coverage. This mediator approach allows synchronization to propagate beyond direct base station coverage while maintaining reliability through priority-based selection of reference sources and multiple synchronization paths

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent adds a new dimension to clock synchronization by enabling device-to-device sidelink communication as an additional synchronization path alongside traditional network-based synchronization. This creates a multi-dimensional synchronization architecture where terminal devices can synchronize through both network coverage and peer-to-peer sidelink channels

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If multiple clock synchronization reference sources are available, then synchronization probability is improved, but selection complexity increases

Engineering Contradiction:
Improvesynchronization probabilityVSAvoidselection mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter of reference source selection by introducing priority values associated with different reference sources. Terminal devices compare priority parameters to automatically select the most appropriate reference source, transforming a complex multi-criteria decision problem into a simpler parameter-based selection process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent enables terminal devices to autonomously select their own clock synchronization reference sources based on predefined priority rules and current reception conditions. Each terminal device independently evaluates available reference sources and makes selection decisions without requiring complex centralized control, reducing overall system complexity

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4665016A1Clock synchronization method and apparatus
Publication Date: 2025.12.17 HUAWEI TECH CO LTD
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AI summary

This application relates to a clock synchronization method and apparatus. A first terminal device receives at least one piece of clock synchronization information, where the at least one piece of clock synchronization information includes first clock synchronization information, and the first clock synchronization information is received from a second terminal device through a sidelink. The first terminal device selects a clock synchronization reference source based on the at least one piece of clock synchronization information. In embodiments of this application, a terminal device can also send clock synchronization information. For example, although a terminal device outside a coverage area of a base station cannot receive clock synchronization information from the base station, the terminal device may still receive clock synchronization information from another terminal device through a sidelink, so that a probability of implementing clock synchronization between the terminal device and a network is increased.