5G Network Node Event Exposure for RAN Clock Status

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Solution Overview

Problem

Existing technologies lack a coordinated operation mechanism for network time synchronization status collection among terminals, AMF, and TSCTSF in 5G networks, particularly in NR Release 18, where methods for distributing RAN clock quality information are incomplete.

Innovation Solution

A network node is introduced with reception, control, and transmission units to manage terminal presence and synchronization status changes, allowing coordinated operations between AMF and TSCTSF by defining 'same clock status areas' or 'gNB-ID' based areas of interest, and updating [SUPI, clock status] lists.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a terminal transmits a registration request upon recognizing clock status change, then the terminal can report its time synchronization status, but the coordination between AMF and TSCTSF is insufficient and detailed operation is not specified

Engineering Contradiction:
Improvetime synchronization status collectionVSAvoidcoordination mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an event exposure mechanism where the AMF acts as an intermediary between the base station and TSCTSF. The AMF subscribes to RAN time synchronization status change events from the base station and exposes these events to TSCTSF, enabling coordinated operation without direct complex interactions between all components.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback loop where terminals report their clock status to the AMF through registration requests, the AMF monitors RAN time synchronization status changes, and this information is exposed to TSCTSF. This closed-loop feedback mechanism ensures reliable time synchronization status collection while maintaining manageable system complexity.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If the system monitors RAN clock quality changes for all terminals, then accurate time synchronization status can be obtained, but the signaling overhead and network load increase

Engineering Contradiction:
Improveclock status monitoring accuracyVSAvoidnetwork signaling overhead
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent applies local quality by having the AMF subscribe to time synchronization status change events at the base station level rather than monitoring all terminals continuously. The system only generates notifications when actual status changes occur in specific local areas (cells), reducing overall network signaling overhead while maintaining monitoring accuracy where needed.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Instead of continuous monitoring, the system uses event-triggered periodic action where the AMF subscribes to status change events and receives notifications only when changes occur. This approach reduces signaling overhead compared to continuous monitoring while ensuring accurate detection of time synchronization status changes when they happen.

Inventive Principle:
Principle #19Periodic action

3Reliability

If detailed coordinated operation between terminals, AMF and TSCTSF is implemented, then complete time synchronization status collection is achieved, but the system complexity and configuration difficulty increase

Engineering Contradiction:
Improvecoordinated operation completenessVSAvoidsystem configuration ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent implements preliminary action by having the AMF pre-subscribe to RAN time synchronization status change events from base stations before actual time synchronization issues occur. This advance preparation ensures that when terminals need to report their status or when clock changes occur, the AMF is already positioned to receive and forward this information to TSCTSF, achieving complete coordination without complex real-time configuration.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4615075A1Network node and communication method
Publication Date: 2025.09.10 NTT DOCOMO INC
  • EP4615075A1 patent drawingFigure 1
  • EP4615075A1 patent drawingFigure 2
  • EP4615075A1 patent drawingFigure 3

AI summary

A network node includes: a reception unit configured to receive a registration request including a network time synchronization support indication from a terminal and to receive a subscription request for exposure of an event related to presence of a terminal in an area of interest, the event including a RAN time synchronization status change event from another network node; a control unit configured to determine a terminal presence status indicating: whether or not the terminal is present in the area of interest; and whether the terminal has come into, or has gone out of, the area of interest, based on a base station through which the registration request is received; and a transmission unit configured to transmit a result of the determination of the terminal presence status of the terminal to the another network node.