Handling Radio Link Failure in Multi-RAT Dual Connectivity
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Solution Overview
Problem
In Multi-RAT dual connectivity (MRDC) systems, Radio Link Failure (RLF) events on the Master Node (MN) lead to unnecessary data loss on the Secondary Node (SN) due to premature release of data activity, affecting scenarios like eMBB, uRLLC, and VoLTE.
Innovation Solution
The method involves detecting RLF with the master node, determining the Secondary Node termination condition, and maintaining or releasing the connection with the SN accordingly, while continuing data activity on the SN until the termination condition is met and initiating a timer and RRC connection re-establishment procedure only for the master node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE releases the entire SCG configuration upon initiation of RRC connection re-establishment procedure, then the RLF recovery procedure can be initiated, but data activity on the SN is stopped causing data loss
Solution Approach 1:
The patent segments the radio bearer configuration into two independent parts: MCG (Master Cell Group) and SCG (Secondary Cell Group). When RLF occurs on MN, only the MCG configuration is released and re-established, while the SCG configuration is preserved and data activity continues on the SN. This segmentation allows independent handling of each node's configuration, preventing unnecessary data loss on the SN.
Solution Approach 2:
The patent extracts the SCG configuration release action from the RLF recovery procedure. Instead of releasing the entire SCG configuration when RLF occurs on MN, the procedure now only releases MCG configuration. The SCG configuration is taken out of the release scope, allowing data activity to continue independently on the SN while MN undergoes re-establishment.
2Ease of operation
If the UE stops data activity on the SN during RLF on MN, then the RRC connection re-establishment can proceed, but unnecessary data transfer is interrupted
Solution Approach 1:
The patent segments data activity into two independent streams: one through MN and another through SN. When RLF occurs on MN, the data activity through MN is temporarily interrupted for re-establishment, but the data activity through SN continues uninterrupted. This segmentation of data paths ensures that productivity is maintained on the SN while allowing operational simplicity in MN recovery.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining data activity on the SN throughout the MN RLF recovery process. The SCG configuration is preserved, allowing data transfer to continue seamlessly on the SN without interruption, thus maintaining productivity while the MN undergoes re-establishment procedures.
3Reliability
If the EN-DC release is performed upon RLF detection, then the MN connection can be re-established, but the SN connection is unnecessarily released
Solution Approach 1:
The patent segments the connection release operation into selective MCG release while preserving SCG. Upon RLF detection on MN, the procedure releases only the MCG configuration and maintains the SCG configuration intact. This selective segmentation prevents unnecessary loss of the SN connection while enabling MN re-establishment.
Solution Approach 2:
The patent inverts the traditional approach by not releasing the SCG configuration upon RLF. Instead of following the conventional full release method, the procedure preserves the SCG and only releases MCG, effectively doing the opposite of the traditional EN-DC release behavior to prevent unnecessary connection loss.
Data Source
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AI summary
Embodiments herein disclose a method for handling RLF in a MRDC system comprising a UE connected to a Master Node and at least one Secondary Node (SN). The method includes detecting, by the UE, a radio link failure (RLF) with the master node. Further, the method includes determining, by the UE, whether a Secondary Node termination condition is met. Further, the method includes performing one of: maintaining, by the UE, a connection with the at least one secondary node till the SN termination condition is met in response to determining that the SN termination condition is not met, and releasing, by the UE, the connection with the at least one secondary node in response to determining that the SN termination condition is met.