Conditional Handover Coordination for Valid SCG Configuration
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Solution Overview
Problem
In 5G NR systems, the coexistence of conditional handover (CHO) and conditional PSCell change (CPC) configurations can lead to double resource reservation and invalidation of CHO-DC configurations due to delta SCG configurations, causing signaling overhead and delayed handover execution.
Innovation Solution
Implementing a method where the source master node provides existing CPC-related information during CHO preparation to the target master node, ensuring the target secondary node is aware of ongoing CPC preparations, thus providing a full SCG configuration to avoid double resource reservation and maintain configuration validity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If delta SCG configuration is used in CHO-CPC coexistence, then configuration flexibility is improved, but SCG configuration validity is compromised and double resource reservation occurs
Solution Approach 1:
The target secondary node receives information about ongoing CPC preparations from the source master node before finalizing the CHO configuration. This preliminary action allows the system to proactively identify potential conflicts between CHO and CPC procedures, enabling the target secondary node to adjust its resource allocation and configuration strategy in advance, thereby preventing double resource reservation and maintaining configuration validity.
Solution Approach 2:
The system implements a feedback mechanism where the target secondary node communicates with the source master node to obtain status information about ongoing CPC preparations. This feedback loop enables the target secondary node to make informed decisions about CHO configuration, ensuring that the SCG configuration remains valid by coordinating with existing CPC operations rather than conflicting with them.
2Speed
If target secondary node independently prepares resources for CHO, then resource allocation speed is improved, but double resource reservation occurs
Solution Approach 1:
The target secondary node receives feedback from the source master node regarding ongoing CPC preparations, including information about already reserved resources. This feedback enables the target secondary node to adjust its resource allocation to avoid duplicating reservations, thereby maintaining fast resource allocation speed while preventing wasteful double resource reservation.
Solution Approach 2:
The source master node acts as an intermediary that coordinates between the target secondary node and the CPC preparation process. By relaying information about ongoing CPC preparations to the target secondary node, the source master node enables coordinated resource allocation that prevents double reservation while maintaining the speed benefits of independent preparation.
3Extent of automation
If CHO and CPC procedures run independently, then procedure execution autonomy is improved, but configuration conflicts and delays occur
Solution Approach 1:
The system maintains procedural autonomy by allowing CHO and CPC to execute independently while implementing feedback mechanisms that exchange status information between procedures. The target secondary node receives feedback about ongoing CPC preparations, enabling it to adjust its timeline and coordination strategy without compromising its autonomous execution, thereby avoiding delays while maintaining independence.
Solution Approach 2:
The system performs preliminary actions by having the target secondary node receive information about ongoing CPC preparations before finalizing CHO configuration. This preliminary coordination allows both procedures to maintain their autonomous execution while being aware of each other's status, preventing conflicts and delays that would otherwise require centralized coordination.
Data Source
AI summary
In some examples, a method, performed in a target master node of a radio network, for preparing handover of user equipment, UE, in dual connectivity, DC, where the handover is between respective primary cells, PCells, of a source master node and a target master node, and respective primary secondary cells, PSCells, of a source secondary node and a target secondary node, comprises receiving, from the source master node, a conditional handover, CHO, request message comprising a unique identifier for the UE defined between the source master node and the target secondary node, and an identifier for the target secondary node, transmitting the unique identifier for the UE to the target secondary node as part of an secondary node addition request for CHO with DC preparation, receiving, from the target secondary node, an acknowledgement message to confirm CPC preparation for the UE, the acknowledgement message comprising a full secondary cell group, SCG, configuration.