F1 Interface Suspend-Resume for Satellite gNB-DU Handover

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Solution Overview

Problem

In non-terrestrial networks (NTN), the centralized network device change procedure is complex due to the need to maintain connectivity and configure interfaces as the gNB-DU moves between different gNB-CU areas, potentially causing service breaks for UEs.

Innovation Solution

The proposed solution optimizes the F1 interface configuration procedure by allowing the gNB-DU to maintain connectivity with both gNB-CUs for a duration, enabling seamless handovers without breaking service. This involves optimizing power consumption and computing requirements, and reducing unnecessary information transfer during interface setup and teardown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If full F1 configuration parameters are transmitted to the new gNB-CU during satellite handover, then the interface can be properly set up, but the procedure becomes complicated and service may be broken

Engineering Contradiction:
Improveservice continuityVSAvoidconfiguration procedure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the necessary F1 configuration parameters that are specific to the new gNB-CU, rather than transmitting the complete configuration set. This selective parameter transmission simplifies the handover procedure while ensuring the new gNB-CU receives exactly what it needs to establish the interface, avoiding the complexity of full configuration transfers.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary configuration actions by maintaining the F1 interface in a suspended state rather than fully tearing it down. The configuration parameters are preserved and can be quickly reactivated when the satellite re-visits the same ground station area, eliminating the need for complete reconfiguration and reducing handover complexity.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the F1 interface is fully set up and torn down during each satellite movement, then connectivity is maintained, but power consumption and computing requirements increase

Engineering Contradiction:
ImproveconnectivityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by suspending the F1 interface during satellite movement and reactivating it when the satellite re-visits the same ground station area. This periodic suspend-resume pattern avoids continuous full interface maintenance, reducing power consumption and computing requirements while maintaining connectivity when needed.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent discards the active interface state during movement but recovers the configuration parameters by suspending rather than fully tearing down the interface. This allows the system to discard unnecessary computational resources during transit while recovering the essential configuration quickly upon return, optimizing power and computing usage.

Inventive Principle:
Principle #34Discarding and recovering

3Ease of operation

If configuration parameters are transferred during each interface setup, then the new gNB-CU can be properly configured, but signaling overhead increases

Engineering Contradiction:
Improveinterface setupVSAvoidsignaling overhead
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The patent extracts and transfers only the essential F1 configuration parameters that are specific to the new gNB-CU during handover, rather than transmitting the complete configuration set. This selective parameter extraction reduces signaling overhead while ensuring the new gNB-CU receives sufficient information for proper interface setup.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary configuration actions by maintaining configuration parameters in a suspended state, so that when the satellite re-visits the same ground station area, the parameters are already available and do not need to be re-transferred, significantly reducing signaling overhead for subsequent handovers.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3925409B1Centralized network device change procedure
Publication Date: 2025.06.18 NOKIA TECHNOLOGIES OY
  • EP3925409B1 patent drawingFigure 1
  • EP3925409B1 patent drawingFigure 2~3
  • EP3925409B1 patent drawingFigure 4~5

AI summary

Embodiments of the present disclosure relate to a centralized network device change procedure. A method comprises in response to a distributed network device being to be disconnected with a centralized network device and connected with a further centralized network device, transmitting an interface resuming request from a distributed network device to the further centralized network device, the interface resuming request being used for resuming an inactivated interface between the further centralized network device and the distributed network device, the terminal device is served by the centralized network device via the distributed network device; and in response to receiving, from the further centralized network device, a resuming status message indicating the interface is successfully resumed, activating the inactivated interface to complete the resume procedure. In this way, when a gNB-DU, which is located at the satellite and moves along with the satellite, moves from the coverage of a gNB-CU to the coverage of a new gNB-CU, a terminal device, which is served by a gNB-CU via a gNB-DU, will keep the connection with the gNB-CU, such that the connectivity of the accessed terminal device will be maintained and meanwhile the signalling overhead for interface configuration will be saved.