Dual-Connectivity Handover Coordination for CHO and CPC Validity
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Solution Overview
Problem
In 5G NR systems, the coexistence of conditional handover (CHO) and conditional PSCell change (CPC) configurations leads to issues such as invalid delta configurations and double resource reservations during handover procedures, resulting in signaling overhead and delayed configurations.
Innovation Solution
A method is introduced to manage CHO-DC configuration validity by transmitting a unique identifier and delta SCG configuration to the source master node, allowing for a second delta SCG configuration to be prepared and maintained after CPC execution, ensuring valid resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a CHO configuration with SCG delta configuration is transmitted to the source MN, then handover preparation is enabled, but the delta configuration becomes invalid when a CPC procedure is executed afterwards
Solution Approach 1:
The patent applies preliminary action by preparing a second delta SCG configuration in advance at the target SN, specifically for the scenario where a CPC procedure is executed before the CHO. This pre-prepared configuration ensures that when the CPC procedure occurs, the target SN already has the necessary configuration ready, preventing the invalidation problem and ensuring continuous configuration validity throughout the handover process.
2Adaptability or versatility
If the target SN prepares resources for both CHO and CPC procedures, then both procedures can be supported, but double resource reservation occurs
Solution Approach 1:
The patent applies merging by integrating the resource preparation processes for CHO and CPC procedures. The target SN identifies when a UE is subject to both procedures and merges the resource reservations, preparing a single set of resources that serves both procedures. This eliminates double resource reservation while maintaining support for both CHO and CPC procedures, optimizing resource utilization.
3Device complexity
If the target MN is unaware of CPC procedure configuration, then CHO configuration can be prepared independently, but coordination between procedures is lost
Solution Approach 1:
The patent applies feedback by implementing an indication mechanism where the source MN informs the target MN about the CPC procedure configuration. The source MN transmits an indication to the target MN when a CPC procedure is configured for a UE, providing feedback about the procedural state. This enables the target MN to coordinate its actions with the CPC procedure, ensuring proper configuration validity and procedure coordination without excessive complexity.
Data Source
AI summary
In some examples a method, performed in a target master node (MN) of a radio network, for preparing handover of user equipment, UE, in dual connectivity, DC, where the handover is between primary cells (PCells) of source MNs and target MNs as well as the primary secondary cells (PSCells) between source secondary nodes (SNs) and target SNs, comprises transmitting, to the source MN, a CHO with DC configuration comprising a unique identifier for a UE defined between the source master node and the target secondary node, and for a secondary cell group (SCG) delta configuration, config1, of the target SN, receiving, from the Source MN, an indication representing a CPC procedure configured after transmission of the CHO with DC configuration, the unique identifier for the UE, and the identifier for the target SN, and transmitting a request to the target SN to prepare a second delta SCG configuration, config2, to be used by the UE in the event that a source MN initiated CPC procedure is executed.