UE PScell Relocation for SCG Radio Link Failure Recovery
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Solution Overview
Problem
In dual connectivity scenarios, especially in LTE and NR systems, radio link failures (RLF) in Secondary Cell Groups (SCG) lead to prolonged service interruptions and increased signaling load due to reliance on the Master eNB for SCG re-establishment, which is time-consuming and inefficient.
Innovation Solution
The user equipment (UE) initiates a PScell relocation procedure directly with the SCgNB upon detecting SCG RLF, attempting recovery over the air interface and triggering a random access procedure to select a new suitable cell within the SCG, thereby minimizing service disruption and signaling latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE relies on the Master eNB for SCG re-establishment, then the re-establishment procedure is centralized and controlled, but the service interruption time is prolonged and signaling load is increased
Solution Approach 1:
The patent segments the SCG re-establishment procedure by allowing the UE to independently initiate recovery procedures directly with the SCgNB, separating this function from the Master eNB-controlled process. This segmentation enables parallel processing paths where the UE can autonomously attempt recovery while the Master eNB maintains overall coordination, thereby reducing service interruption time while preserving re-establishment reliability through multiple recovery pathways
Solution Approach 2:
The patent introduces an intermediary random access procedure as a mediator between the UE and SCgNB for direct communication during SCG re-establishment. This intermediary mechanism enables the UE to directly establish connectivity with the SCgNB without requiring full Master eNB involvement in the initial recovery phase, reducing signaling load and service interruption while maintaining controlled re-establishment through the structured random access protocol
2Reliability
If the UE relies on the Master eNB for SCG re-establishment, then the re-establishment process is coordinated centrally, but the signaling load is increased
Solution Approach 1:
The patent extracts the direct communication function from the Master eNB-controlled re-establishment process, allowing the UE to independently initiate and complete random access procedures with the SCgNB. This extraction removes unnecessary signaling through the Master eNB for routine SCG recovery operations, significantly reducing signaling load while maintaining re-establishment reliability through the preserved RRC connection and direct UE-SCgNB communication channel
Solution Approach 2:
The patent enables the UE to perform self-service during SCG re-establishment by autonomously initiating random access procedures and directly communicating with the SCgNB without requiring Master eNB mediation for each signaling exchange. This self-service capability reduces the quantity of signaling messages required while maintaining reliable re-establishment through the UE's ability to independently manage the recovery process within the dual connectivity framework
Data Source
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Figure 3a~3b
AI summary
A method comprises monitoring for a radio link failure associated with a secondary cell of a secondary base station. This may be a PScell. A user device may select a second secondary cell as a target secondary cell. The user device initiates a relocation procedure with the target secondary cell.