Conditional L1/L2 Handover with Early Cell Synchronization

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Solution Overview

Problem

Existing 5G wireless communication systems face challenges in managing increased communication traffic and supporting efficient mobility between different base stations due to delays in cell switch decisions and radio link failures, particularly in network-based LTM procedures.

Innovation Solution

Implementing a method and apparatus for controlling execution conditions and processing terminal configuration to support UE-based Conditional LTM, which includes receiving a conditional LTM configuration, evaluating execution conditions, and performing early synchronization with candidate cells based on beam quality thresholds and timing advance information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If network-based LTM procedures are used, then centralized control is maintained, but delays in cell switch decisions and radio link failures occur

Engineering Contradiction:

Improvemobility handover reliabilityVSAvoidcell switch decision delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The terminal performs autonomous cell switch decisions based on pre-configured execution conditions and early synchronization results, without requiring real-time network intervention. The terminal evaluates conditions such as beam quality thresholds and timing advance information locally, enabling self-service mobility that eliminates decision delays while maintaining reliability through pre-configured parameters.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The network pre-configures the terminal with conditional LTM parameters including execution conditions, beam quality thresholds, and timing advance information before handover is needed. This preliminary configuration allows the terminal to immediately execute handover when conditions are met, eliminating real-time decision delays while maintaining centralized control over the handover parameters.

Inventive Principle:

Principle #10Preliminary action

2Speed

If early synchronization is performed with candidate cells, then handover speed is improved, but terminal processing complexity increases

Engineering Contradiction:

Improvehandover execution speedVSAvoidterminal processing complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The terminal performs early synchronization and condition evaluation only for specific candidate cells that meet pre-defined execution conditions, rather than all possible target cells. This localized processing approach reduces overall terminal complexity by focusing computational resources only on relevant handover candidates, while still achieving fast handover execution when conditions are met.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The terminal uses pre-configured parameters such as beam quality thresholds and timing advance values to simplify the decision-making process. By changing the evaluation criteria to use these fixed parameters rather than complex real-time analysis, the terminal achieves fast handover execution with reduced processing complexity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conditional LTM configuration is implemented, then mobility efficiency is enhanced, but signaling overhead increases

Engineering Contradiction:

Improvemobility efficiencyVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The network sends a single pre-configuration message containing all necessary conditional LTM parameters including execution conditions, candidate cell information, and timing advance values before handover is needed. This preliminary action consolidates multiple potential signaling exchanges into one, reducing overall signaling overhead while enabling efficient mobility when conditions are met.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The terminal stores and reuses the pre-configured conditional LTM parameters locally for multiple evaluation cycles without requiring repeated network signaling. This copying approach allows the terminal to efficiently evaluate execution conditions and perform handovers using stored parameter copies, significantly reducing signaling overhead while maintaining high mobility efficiency.

Inventive Principle:

Principle #26Copying

Data Source

PatentEP4712570A1Conditional l1l2 handover with early synchronisation

Publication Date: 2026.03.18 KT CORP

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AI summary

Provided are a method and apparatus for controlling mobility in a wireless communication system. The method of the terminal may include receiving a conditional layer 1 (L1)/layer 2 (L2) triggered mobility (LTM) configuration, after receiving the conditional LTM configuration, performing an evaluation of an execution condition for conditional LTM and an early synchronization to a candidate cell, and executing the conditional LTM based on the performed evaluation of the execution condition and the performed early synchronization.