Conditional Mobility User Plane Reconfiguration via Delta RRC Comparison
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Solution Overview
Problem
The existing conditional mobility procedures in 3GPP Release 16 and later versions face increased signaling latency and internal signaling overhead due to repeated user plane configuration updates across multiple target cells, especially during DRB configuration changes, which counter the goal of allowing subsequent cell group changes without reconfiguration.
Innovation Solution
A method involving obtaining and comparing delta RRC configurations between source and target network elements to determine identity, thereby skipping unnecessary RRC reconfiguration messages to the UE, reducing redundant signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user plane configuration updates are performed for every DRB configuration change during conditional mobility procedures, then configuration alignment between UE and target node is ensured, but signaling latency and internal signaling overhead are increased
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple target cells with their RRC configurations before the actual handover occurs. The network prepares delta RRC configurations for candidate target cells in advance, so that when handover is needed, the configurations are already ready and can be applied immediately without repeated signaling updates during the mobility procedure.
Solution Approach 2:
The patent utilizes parameter changes by introducing a comparison mechanism that evaluates whether delta RRC configurations have changed before transmitting reconfiguration messages to the UE. This parameter comparison (whether configurations are identical or not) enables the system to skip unnecessary reconfiguration signaling when no changes occur, thereby reducing signaling latency while maintaining configuration alignment.
2Reliability
If RRC reconfiguration messages are transmitted to UE for every DRB configuration update, then configuration consistency is maintained, but internal signaling overhead is increased
Solution Approach 1:
The patent implements parameter changes by introducing a comparison mechanism that evaluates whether delta RRC configurations have changed before transmitting reconfiguration messages to the UE. This parameter comparison (whether configurations are identical or not) enables the system to skip unnecessary reconfiguration signaling when no changes occur, thereby reducing signaling overhead while maintaining configuration consistency.
Solution Approach 2:
The patent applies partial action by selectively transmitting RRC reconfiguration messages only when necessary (when delta configurations differ), rather than transmitting them for every update regardless of actual changes. This partial transmission approach reduces unnecessary signaling overhead while ensuring configuration consistency is maintained only when actually needed.
3Device complexity
If delta RRC configurations are compared to skip unnecessary reconfigurations, then signaling overhead is reduced, but configuration update responsiveness may be delayed
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple target cells with their RRC configurations before the actual handover occurs. The network prepares delta RRC configurations for candidate target cells in advance, so that when handover is needed, the configurations are already ready and can be applied immediately without repeated signaling updates during the mobility procedure.
Data Source
AI summary
A method for supporting a conditional mobility procedure involving a source network element serving a user equipment (UE) and at least one target network element, the method including obtaining a first delta radio resource control (RRC) configuration; storing the first delta RRC configuration; obtaining a second delta RRC configuration that is indicative of a difference between a RRC configuration of the source network element and an RRC configuration of the target network element; comparing the obtained second delta RRC configuration with the stored first delta RRC configuration to determine whether the first and second delta RRC configurations are identical or not; based on determining that the first and second delta RRC configurations are not identical: transmitting an RRC reconfiguration message to the UE; and based on determining that the first and second delta RRC configurations are identical: skipping the transmission of the RRC reconfiguration message to the UE.