UE Handover Fallback Between DAPS and Conditional Handover
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Solution Overview
Problem
Existing handover procedures in 5G wireless communication systems face challenges in achieving both mobility robustness and minimizing service interruptions, particularly when transitioning from dual-active protocol stack (DAPS) to conditional handover (CHO), as they may result in unnecessary protocol stack configurations and resource wastage due to unreliable source links.
Innovation Solution
A method and apparatus that allow fallback from dual-active protocol stack (DAPS) to conditional handover (CHO) by dynamically determining the availability of the source radio link, enabling a UE to switch to CHO only when the source link is insufficient, thereby reducing unnecessary protocol stack configurations and resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual-active protocol stack handover is used to ensure mobility robustness, then handover reliability is improved, but protocol stack configuration complexity and resource consumption increase
Solution Approach 1:
The patent implements dynamic selection between DAPS handover and CHO based on real-time assessment of source link availability. The UE evaluates whether the source link can support dual-active protocol stack operation, and dynamically switches to CHO when the source link is unavailable, thereby adapting the handover mode to current network conditions and avoiding unnecessary protocol stack configurations.
Solution Approach 2:
The patent changes the handover mode parameter based on source link availability conditions. When the source link is available, DAPS handover is used for enhanced reliability. When the source link is unavailable, the system transitions to CHO mode, effectively changing the operational parameter to match network conditions and reduce resource consumption.
2Loss of time
If dual-active protocol stack handover is used to maintain service continuity, then service interruption time is reduced, but network resource consumption increases
Solution Approach 1:
The system dynamically adjusts handover behavior based on source link availability. When the source link is unavailable, the UE falls back to CHO which eliminates the need to maintain dual protocol stacks, thereby reducing network resource consumption while still providing service continuity through alternative handover paths.
Solution Approach 2:
The patent discards the DAPS handover configuration when source link availability assessment fails, and recovers to using CHO instead. This avoids wasting network resources on maintaining protocol stacks that cannot be supported by the source link, while still achieving service continuity through the alternative CHO mechanism.
3Reliability
If DAPS handover configuration is always applied, then mobility robustness is maximized, but unnecessary protocol stack configurations occur when source link is unavailable
Solution Approach 1:
The patent performs preliminary assessment of source link availability before initiating handover procedure. This preliminary action determines whether DAPS handover can be properly executed, and only applies it when the source link is actually available. When the source link is unavailable, the system preliminarily determines that CHO is the appropriate mode, preventing unnecessary protocol stack configurations.
Solution Approach 2:
The system uses feedback from source link availability assessment to determine the appropriate handover mode. The assessment result feeds back into the handover decision-making process, allowing the UE to select DAPS when conditions permit and fall back to CHO when the source link cannot support dual-active operation, thereby avoiding wasteful protocol stack configurations.
Data Source
AI summary
A method and apparatus may include receiving, by a user equipment from a source cell, a first configuration configured for conditional handover and dual active protocol stack handover with a reduced target cell configuration, and a second configuration configured for conditional handover only. The method may further include determining, by the user equipment, the availability of at least one radio link associated with the source cell. The method may further include performing, by the user equipment, a conditional handover procedure according to at least one of the received configurations based upon the determination.