Cell Switching Mobility Management Across CU Boundaries

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Solution Overview

Problem

Intra-CU Layer 1/Layer 2 (L1/L2) triggered mobility (LTM) is only supported for mobility between cells within the same Next Generation Node B (gNB) or within the same CU, limiting its application opportunities.

Innovation Solution

A method for mobility management that enables cell switching within the same CU or between different CUs by using serving cell's group identifiers to determine whether an inter-CU level configuration is needed, which includes security key updates, PDCP entity re-establishment, or RRC configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If intra-CU LTM is used for mobility between cells within the same CU, then mobility latency is reduced, but the applicability is limited to intra-CU mobility only

Engineering Contradiction:

Improvemobility latencyVSAvoidapplicability range

Core Design Contradiction:

Loss of timeVSAdaptability or versatility

Solution Approach 1:

The patent extends the LTM mechanism to support both intra-CU and inter-CU mobility scenarios by introducing a unified configuration approach. The CU group identifier enables the system to determine whether inter-CU configuration is needed, allowing the same LTM mechanism to function across different CU boundaries, thus making the mobility management system universal and applicable to various mobility scenarios without requiring separate mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If L3 level configuration is used for inter-CU mobility, then comprehensive configuration is achieved, but mobility latency increases

Engineering Contradiction:

Improveconfiguration completenessVSAvoidmobility latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the configuration requirements into two parts: common configuration parameters that can be handled by the faster L1/L2 LTM mechanism, and specific inter-CU configuration parameters (such as security key updates, PDCP entity re-establishment, and RRC configuration) that require L3 level processing. This segmentation allows the system to apply the appropriate configuration depth based on the mobility scenario, reducing unnecessary latency while maintaining configuration completeness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

For inter-CU mobility, the patent applies partial L3 level configuration rather than complete L3 reconfiguration. By using the CU group identifier to selectively determine which inter-CU level configurations are needed, the system performs only the necessary partial configuration actions, avoiding the full overhead of traditional L3 level configuration while still ensuring all required configurations are applied.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP4648479A1Method of mobility management and device using the same

Publication Date: 2025.11.12 IND TECH RES INST

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AI summary

A method of mobility management, a user equipment, and a base station are provided. The method includes receiving a network configuration, wherein the network configuration includes at least one candidate configuration, a serving cell's group identifier, and a group identifier for each of the at least one candidate configuration. Storing the serving cell's group identifier. Receiving a signaling for triggering a cell switching. The serving cell's group identifier is used by the UE to determine whether an inter- centralized unit (inter-CU) level configuration is needed or not upon the cell switching. The inter-CU level configuration includes at least one of the following: a security key update, a packet data convergence protocol (PDCP) entity reestablishment, or a radio resource control (RRC) configuration.