SDT Configuration Transfer Across RAN Nodes for Handover Recovery
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Solution Overview
Problem
The management of Small Data Transmission (SDT) configuration parameters is unclear when a User Equipment (UE) in the RRC_CONNECTED state detects a radio link failure and performs an RRC reestablishment procedure, particularly in cases where the UE transitions between RRC_INACTIVE and RRC_CONNECTED states.
Innovation Solution
A method where a first RAN node transfers SDT configuration parameters to a UE, receives a UE context request message from a second RAN node, and transmits a UE context response message including a portion of the SDT configuration parameters, while a second RAN node receives an update message for a RAN notification area and transmits a UE context request message with SDT configuration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs RRC reestablishment procedure after radio link failure, then the radio connection is restored, but the SDT configuration parameters may be lost or inconsistent across RAN nodes
Solution Approach 1:
The first RAN node stores the SDT configuration parameters before the UE performs RRC reestablishment. When the UE reconnects, the configuration is retrieved and transferred, ensuring continuity without requiring reconfiguration. This preliminary storage action prevents information loss during the radio link failure and recovery process.
Solution Approach 2:
The first RAN node acts as an intermediary that holds and transfers the SDT configuration parameters between the network and the UE during reestablishment. By maintaining the configuration in the RAN node's memory and transferring it upon UE reconnection, the system ensures configuration consistency without requiring the UE to retain it through the failure state.
2Reliability
If the SDT configuration parameters are transferred between RAN nodes during handover, then configuration consistency is maintained, but the signaling overhead and processing time increase
Solution Approach 1:
The SDT configuration parameters are stored in the first RAN node before handover is initiated. When the UE requests handover to a second RAN node, the configuration is already available and can be quickly transferred via the handover request message, avoiding the need for generation or retrieval during the critical handover execution phase.
Solution Approach 2:
The SDT configuration parameters are copied from the first RAN node's stored information to the handover response message sent to the second RAN node. This copying mechanism ensures the configuration is accurately transferred without requiring complex processing or regeneration at the target node, reducing handover processing time.
Data Source
AI summary
A first radio access network (RAN) node communicating with a second RAN node can implement a method for transferring user equipment (UE) configuration parameters. The method includes: (i) transmitting, from the first RAN node to the UE, SDT configuration parameters for configuring the UE; (ii) receiving, at the first RAN node and from the second RAN node, a UE context request message; and (iii) transmitting, from the first RAN node to the second RAN node, a UE context response message including at least a portion of the SDT configuration parameters.