Split Bearer Resource Management in Dual Connectivity
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Solution Overview
Problem
In radio communication systems using dual connectivity between LTE and NR, the frequent release and re-setting of split bearers via secondary cell groups lead to increased signaling and power consumption, especially when user equipment moves between coverage areas, and maintaining the secondary cell group despite radio link failures results in unnecessary quality measurements.
Innovation Solution
Implementing a method where the radio communication system partially releases the split bearer's resources upon detecting a radio link failure, allowing the user equipment to deactivate the secondary cell group and reduce power consumption, while maintaining the signaling path through the master cell group, thereby reducing the frequency of bearer re-settings and quality measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the split bearer is frequently released and re-set when UE moves between coverage areas, then the dual connectivity can be maintained, but the signaling amount increases
Solution Approach 1:
The patent segments the bearer resources into two parts: the PDCP layer resources are maintained and preserved, while only the lower layer (RLC, MAC, PHY) resources are released. This segmentation allows the higher layer configuration to be retained without maintaining the full bearer path, reducing signaling overhead while preserving the ability to quickly re-establish connectivity.
Solution Approach 2:
The system performs preliminary actions by maintaining the PDCP layer configuration and bearer identity before actual movement occurs. When the UE moves and needs to re-establish dual connectivity, the pre-preserved PDCP configuration allows for faster re-setup without requiring complete re-negotiation of bearer parameters, thus reducing signaling amount.
2Reliability
If the secondary cell group is maintained despite radio link failure, then the connected state is preserved, but power consumption increases due to unnecessary quality measurements
Solution Approach 1:
The patent implements dynamic state management where the secondary cell group resources can be released upon radio link failure, transitioning from an active measurement state to a dormant state. The PDCP layer configuration is preserved but lower layer resources are released, allowing the system to dynamically adjust resource usage based on actual connectivity needs, thereby reducing power consumption during poor radio conditions.
Solution Approach 2:
Instead of maintaining the full secondary cell group configuration (which would require continuous quality measurements), the patent applies partial action by releasing only the lower layer resources (RLC, MAC, PHY) while keeping the PDCP layer intact. This partial maintenance strategy reduces the measurement burden and power consumption while preserving the ability to quickly restore connectivity when conditions improve.
Data Source
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AI summary
Upon receiving, from UE (200), SCG Failure Information that indicates that a radio link failure has occurred in a secondary cell group, eNB (100A) transmits, to gNB (100B), Secondary Node Modification Request to instruct to release a resource of a split bearer of only a predetermined layer and the layers below thereof in the secondary cell group. Based on the received Secondary Node Modification Request, the gNB (100B) releases the resource of the split bearer below the predetermined layer in the secondary cell group. The eNB (100A) deletes setting itself of the secondary cell group when a bearer belonging to the secondary cell group other than the split bearer is not set.