Master Node CPC Handling in Dual Connectivity
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Solution Overview
Problem
The complexity of processing inter-SN conditional PSCell changes in radio communication systems, particularly when both MN-initiated and SN-initiated inter-SN CPCs are configured simultaneously, leading to potential misinterpretation of SN Release Request messages and excessive restriction of inter-SN CPC opportunities due to unclear rejection reasons by the T-SN.
Innovation Solution
A RAN node configured to operate as a Master Node in dual connectivity, which prevents the initiation of SN-initiated inter-SN CPCs during ongoing MN-initiated inter-SN CPCs, and sends specific information in SN Release Request messages to distinguish between normal and inter-SN CPC procedures, allowing the T-SN to provide detailed rejection messages indicating unacceptable inter-SN CPCs or specific candidate cell issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If both MN-initiated inter-SN CPC and SN-initiated inter-SN CPC are configured simultaneously, then the system provides more mobility options for the UE, but the processing complexity of the network and UE increases significantly
Solution Approach 1:
The patent extracts the SN-initiated inter-SN CPC functionality during ongoing MN-initiated inter-SN CPC procedures. By preventing SN-initiated CPC when MN-initiated CPC is in progress, the system removes the source of complexity while preserving MN-initiated mobility options. This selective extraction resolves the contradiction by eliminating the problematic overlap without sacrificing overall adaptability.
2Adaptability or versatility
If the S-SN receives an SN Release Request message without clear indication, then the message can be used for both normal release and inter-SN CPC procedures, but the S-SN may misinterpret the message and stop providing user data prematurely
Solution Approach 1:
The patent introduces a new XnAP message (SN Change Required) as an intermediary between the MN and S-SN to clearly indicate inter-SN CPC initiation. This intermediary message serves as a mediator that prevents misinterpretation of the SN Release Request message, allowing the S-SN to distinguish between normal release and CPC procedures. The intermediary preserves message reuse flexibility while ensuring reliable interpretation through explicit indication.
3Productivity
If the T-SN rejects inter-SN CPC requests without providing detailed rejection reasons, then the rejection process is simple, but the MN or S-SN cannot determine whether to retry with different candidate cells
Solution Approach 1:
The patent implements a feedback mechanism where the T-SN provides detailed rejection reasons in the SN Addition Request Reject message. The rejection cause information feeds back to the MN and S-SN, enabling them to understand whether the rejection is due to T-SN unavailability, candidate cell issues, or other factors. This feedback allows intelligent retry decisions with alternative candidate cells, maintaining fast rejection processing while improving CPC opportunity management through informed retry behavior.
Data Source
AI summary
While an MN-initiated inter-SN Conditional Primary Secondary Cell Group (SCG) Cell (PSCell) Change (CPC) from a source Secondary Node (S-SN) (2) to a target SN (T-SN) (4) is in progress with respect to a PSCell of an SCG of the User Equipment (UE) (3), a Master Node (MN) (1) does not configure, prepare, or allow an SN-initiated inter-SN CPC to at least the same T-SN (4) with respect to the same UE (3). For example, this can contribute to avoiding complex processing for Inter-SN CPC.