SCG State Indication in Conditional Handover
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Solution Overview
Problem
In conditional handover scenarios of 3GPP Release 15 mobility, the Secondary Cell Group (SCG) state updates are not dynamic enough, leading to sub-optimal configurations and increased signaling, which can result in race conditions due to differences in delay and changing traffic conditions.
Innovation Solution
A method where the User Equipment (UE) or network nodes indicate the SCG state as activated or deactivated during Conditional Handover (CHO), allowing the target candidate nodes to adjust their configurations accordingly, reducing unnecessary signaling and optimizing SCG state updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SCG state updates are performed frequently to maintain optimal configuration, then configuration accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent implements dynamic SCG state management where the target candidate nodes adjust their SCG configurations based on real-time traffic conditions and handover execution status. The system transitions from static pre-configured SCG states to dynamic state updates triggered by specific events (handover execution, traffic condition changes), thereby maintaining configuration accuracy without excessive signaling.
2Speed
If SCG configuration is updated early to prepare for handover, then handover execution speed is improved, but race conditions increase due to delay differences
Solution Approach 1:
The patent prepares SCG configurations in advance at target candidate nodes during the conditional handover setup phase, but these configurations remain dormant until triggered. The actual SCG state updates are executed preliminarily at the target candidate nodes and synchronized through UE-reported indications, allowing fast handover execution without causing race conditions because the updates are coordinated through the UE's handover execution feedback.
3Reliability
If SCG state is kept activated to maintain connectivity, then connection reliability is improved, but resource consumption increases
Solution Approach 1:
The patent dynamically changes the SCG state parameter (activated/deactivated) at target candidate nodes based on traffic conditions and handover execution status. During conditional handover preparation, SCG may be deactivated to save resources. Upon handover execution or when traffic conditions require it, the SCG state is activated. This parameter switching maintains connection reliability when needed while reducing resource consumption during idle periods.
Data Source
AI summary
A method for indicating a Secondary Cell Group (SCG) state during a Conditional Handover (CHO) in a wireless communications network is provided. The method is performed by a User Equipment (UE), or by a source Master Node (MN). The UE is configured with a current SCG. A CHO configuration for the UE is obtained (1201) from a source MN. The CHO configuration comprises a configuration for a target candidate node. The target candidate node comprises any one or more out of: a target candidate MN and a target candidate Secondary Node (SN). When CHO execution conditions related to the CHO configuration are fulfilled, an indication is sent (1204) to the target candidate node. The indication indicates an SCG state being set to any one out of: SCG activated or SCG deactivated.