Dual RLC Handover Control for Source Link Failure Release
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Solution Overview
Problem
Existing wireless communication systems face challenges in handling source radio link failures during handovers, particularly in enhanced make-before-break scenarios, leading to potential data loss and resource inefficiencies due to unsynchronized release of source and target connections.
Innovation Solution
Implement methods for the UE and source access node to monitor and manage source radio link failures by establishing and maintaining dual RLC entities with both the source and target access nodes, and follow predetermined criteria for releasing the source link only when specific conditions are met, ensuring coordinated release and minimizing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE establishes RLC entities and target radio link with the target access node while keeping RLC entities and source radio link with the source access node, then the handover reliability is improved, but the device complexity increases due to maintaining dual RLC entities
Solution Approach 1:
The patent segments the RLC (Radio Link Control) functionality by maintaining separate RLC entities for both source and target radio links simultaneously. This segmentation allows independent management of source and target connections, enabling the UE to establish the target link while preserving the source link until handover is complete, thereby improving handover reliability without requiring a complete teardown of the source RLC entities
Solution Approach 2:
The patent implements preliminary action by pre-establishing RLC entities and the target radio link before actually releasing the source radio link. The UE configures and tests the target connection in advance, ensuring it is ready to take over seamlessly. This preliminary setup eliminates the need for complex real-time coordination during the actual handover moment, reducing operational complexity while maintaining high reliability
2Productivity
If the source radio link is released immediately after handover, then the resource utilization is improved, but the data loss increases due to unsynchronized release
Solution Approach 1:
The patent employs feedback mechanisms where the UE and source access node continuously monitor the status of the source radio link and coordinated handover progress. Based on this feedback, the system determines the optimal moment to release the source link, ensuring both ends are synchronized and the target link is fully operational before source resources are freed. This feedback loop prevents data loss while optimizing resource utilization by avoiding premature or incomplete releases
3Reliability
If the UE maintains both source and target RLC entities during handover, then the handover reliability is improved, but the loss of time increases due to extended connection maintenance
Solution Approach 1:
The patent applies dynamics by making the RLC entity management adaptive and flexible rather than static. The system dynamically adjusts the lifecycle of source and target RLC entities based on real-time handover progress and network conditions. The source RLC entities are maintained only as long as necessary for coordinated handover, then released promptly once the target link is established and synchronized, optimizing the balance between reliability and time efficiency
Data Source
AI summary
A method performed by a User Equipment, UE, for handling a source radio link during a handover from a source access node to a target access node in a wireless communications network. The UE is triggered to perform the handover. The UE establishes Radio Link Control, RLC, entities and associated target radio link with the target access node, while keeping RLC entities and associated source radio link with the source access node. The UE checks whether a source radio link related failure has occurred. When a source radio link related failure has occurred, the UE checks the radio link related failure against a set of source radio link release UE criteria, and when one or more source radio link release UE criterion is fulfilled out of the set of source radio link release UE criteria, the UE handling the source radio link according to a predetermined rule.