Conditional Handover Execution in Dual Connectivity Before Link Failure
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Solution Overview
Problem
In dual connectivity scenarios, the simultaneous configuration and execution of Conditional Handover (CHO) and Conditional Primary Secondary Cell Addition/Change (CPAC) can lead to radio link failures due to obscured CHO purposes and declining radio link quality, causing interruptions in ongoing services.
Innovation Solution
A method for conditional handover in dual connectivity scenarios where the UE monitors for radio link failures and evaluates target cell quality and time-to-trigger conditions to execute CHO and CPAC simultaneously, prioritizing execution based on predefined threshold values to avoid radio resource control reestablishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE waits for both CHO and CPAC trigger conditions to be met simultaneously, then the handover execution follows the standardized procedure, but the radio link quality may decline and cause radio link failures during the waiting period
Solution Approach 1:
The patent applies preliminary action by allowing the UE to execute CHO before both CHO and CPAC trigger conditions are fully met. The UE evaluates target cell quality and time-to-trigger conditions in advance, and can proceed with handover when sufficient conditions are satisfied, rather than waiting passively for all conditions to be met simultaneously. This proactive approach prevents radio link quality from declining too much during the waiting period.
Solution Approach 2:
The patent introduces dynamic decision-making where the UE continuously monitors radio link quality, target cell quality, and time-to-trigger conditions, and adjusts its handover execution timing based on real-time evaluations. The UE can dynamically choose to execute CHO when it determines that waiting further would cause radio link failure, making the handover process adaptive rather than rigidly following the simultaneous condition requirement.
2Productivity
If the UE executes CHO immediately when trigger conditions are met, then service continuity is maintained, but the original purpose of CHO may become obscured leading to potential radio link failures
Solution Approach 1:
The patent applies feedback by implementing a multi-criteria evaluation system where the UE continuously monitors not only the basic CHO trigger condition but also target cell quality metrics and time-to-trigger conditions. This feedback loop allows the UE to make informed decisions about when to execute CHO, ensuring that handover occurs only when the target cell is sufficiently prepared to maintain radio link stability, thus preventing premature handover while still maintaining service continuity.
Solution Approach 2:
The patent uses preliminary action by requiring the UE to evaluate target cell quality and time-to-trigger conditions before executing CHO. This preliminary evaluation ensures that the handover is performed only when the target cell is ready to maintain reliable connection, preserving the original purpose of CHO while enabling timely execution to maintain service continuity.
3Reliability
If the UE performs RRC connection reestablishment due to radio link failure, then the connection can be restored, but service interruptions occur significantly impacting performance
Solution Approach 1:
The patent applies preliminary action by enabling the UE to execute CHO proactively before radio link failure occurs. By evaluating target cell quality and time-to-trigger conditions in advance and executing handover when sufficient conditions are met, the UE avoids radio link failure and the subsequent RRC connection reestablishment process, thereby eliminating service interruptions and their associated time loss.
Solution Approach 2:
The patent implements beforehand cushioning by preparing the handover execution in advance based on monitored conditions. The UE continuously evaluates target cell quality and time-to-trigger conditions, and is ready to execute CHO immediately when conditions indicate potential radio link failure risk. This preparatory approach cushions against the harmful effects of radio link failure and the resulting service interruptions.
Data Source
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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.