Conditional Handover Control for User Equipment
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Solution Overview
Problem
In mobile communication systems, existing handover methods face challenges in reducing communication interruption time and improving reliability, especially in unstable radio environments, as they rely on base station determination rather than user equipment-driven decisions.
Innovation Solution
A conditional handover method where user equipment receives a RRC message listing candidate cells and handover conditions, allowing it to perform a handover to a specific candidate cell when the conditions are met, including RLC and MAC configurations for seamless transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base station determines handover timing, then handover control is centralized, but communication interruption time increases and reliability decreases in unstable radio environments
Solution Approach 1:
The patent inverts the traditional handover control architecture by enabling user equipment to autonomously determine handover timing based on pre-configured conditions and candidate cell lists, rather than relying on base station decisions. This inversion reduces communication interruption time and improves handover reliability in unstable radio environments by allowing faster, condition-based handover execution without base station intervention delays.
Solution Approach 2:
The patent applies preliminary action by pre-configuring user equipment with candidate cell lists and handover conditions before handover is needed. The base station provides the RRC message containing candidate cells and conditions in advance, enabling the user equipment to immediately execute handover when conditions are met, without waiting for base station determination during the actual handover event.
2Reliability
If base station controls handover decisions, then network control is maintained, but handover reliability deteriorates in unstable radio states
Solution Approach 1:
The patent implements self-service by enabling user equipment to autonomously evaluate handover conditions and select target cells based on measured radio parameters. The user equipment independently determines whether handover conditions are met and executes handover to the appropriate candidate cell without requiring real-time base station decisions, improving adaptability to unstable radio conditions while maintaining network control through pre-configured parameters.
3Reliability
If conditional handover with candidate cell lists is implemented, then handover reliability improves, but message complexity and configuration overhead increase
Solution Approach 1:
The patent manages complexity by performing configuration actions in advance - the base station provides the complete RRC message with candidate cell lists and handover conditions during a stable connection phase. This preliminary configuration allows the user equipment to handle complex evaluation logic locally without requiring complex real-time signaling during handover execution, thus improving reliability while controlling message complexity.
Data Source
AI summary
A handover control method is a method for performing a conditional handover of a user device from a source cell to a target cell, the source cell to which the user device connects. The handover control method comprises: receiving, by the user device from the source cell, a handover command including a list of candidate cells which are candidates for the target cell and a handover condition specified for each of the candidate cells in the list; and when a handover condition corresponding to a specific candidate cell in the list included in the received handover command is satisfied, performing a handover to the specific candidate cell in which the handover condition is satisfied.