Dual Connectivity Handover Timing Under Radio Link Failure

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Solution Overview

Problem

The simultaneous configuration and execution of Conditional Handover (CHO) and Conditional Primary Secondary Cell Addition/Change (CPAC) in dual connectivity scenarios can lead to radio link failures due to unsatisfied execution conditions, causing interruptions in ongoing services.

Innovation Solution

A method for conditional handover in dual connectivity scenarios that involves monitoring radio link quality and execution conditions, deferring execution until both CHO and CPAC conditions are met, and prioritizing simultaneous execution based on improved radio link quality or service quality, thereby avoiding radio resource control re-establishment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE waits for both CHO and CPAC trigger criteria to be satisfied before executing simultaneous handover, then the execution conditions are met, but the radio link quality of the source cell may decline leading to radio link failure and service interruption

Engineering Contradiction:

Improvehandover execution reliabilityVSAvoidservice continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network pre-configures multiple conditional reconfigurations including both CHO and CPAC configurations before the UE needs to handover. This allows the UE to have execution-ready configurations available in advance, eliminating the need to wait for all conditions to be satisfied and preventing radio link failure due to delayed handover execution.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamic prioritization where the UE can adjust the execution order of CHO and CPAC based on real-time radio link quality conditions. When source cell quality degrades below a threshold, the UE prioritizes executing the configuration that ensures immediate connection maintenance, dynamically adapting the handover strategy to current conditions.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the UE prioritizes simultaneous execution of CHO and CPAC, then service continuity is improved, but the complexity of evaluating multiple execution conditions increases

Engineering Contradiction:

Improveservice continuityVSAvoidcondition evaluation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the condition evaluation process into distinct components: source cell quality evaluation, target cell suitability evaluation, and execution priority determination. Each conditional reconfiguration is evaluated independently with its own trigger criteria, allowing the UE to manage complexity by handling evaluations in modular units rather than as a monolithic process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces quality threshold parameters that automatically trigger prioritization decisions. When the source cell quality parameter falls below a predefined threshold, the UE changes its evaluation parameters to prioritize immediate execution over waiting for all conditions, simplifying the decision logic based on parameter state changes.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the UE executes CHO and CPAC simultaneously when conditions are met, then handover robustness is improved, but the risk of radio link failure increases during the waiting period

Engineering Contradiction:

Improvehandover robustnessVSAvoidradio link failure risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The network provides multiple pre-configured conditional reconfigurations that act as cushioning options before radio link failure occurs. These pre-prepared configurations include alternative target cells and SCGs that can be immediately executed if the primary handover path fails, cushioning against the harmful effect of radio link failure during the handover process.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent implements preliminary anti-action by monitoring source cell quality and proactively triggering handover execution before radio link failure can occur. The UE takes preemptive action by executing the configured handover when quality thresholds are approached, counteracting the potential harmful effect of link degradation before it leads to failure.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS20250365632A1Methods and systems to perform conditional handover in dual connectivity scenarios

Publication Date: 2025.11.27 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for conditional handover (CHO) in a dual connectivity scenario in a user equipment (UE), includes: receiving a conditional reconfiguration message for simultaneous execution of CHO and conditional primary secondary cell addition and change (CPAC); monitoring an occurrence of a first event that satisfies each of a CHO trigger criteria and a CPAC trigger criteria for the simultaneous execution of the CHO and the CPAC; detecting a second event corresponding to a declaration of at least one of a radio link failure (RLF), a master cell group (MCG) failure, and a secondary cell group (SCG) failure; and prior to the occurrence of the first event and after the detection of the second event, executing the CHO and the CPAC simultaneously, based on at least one of a radio link quality of each of a target MCG and a target SCG and a status of a time-to-trigger (TTT) for each of the target MCG and the target SCG.