Inter-Master Conditional Handover Coordination for Secondary Node Changes
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Solution Overview
Problem
In cellular networks with dual connectivity, the coordination between conditional handover of a master node (CHO) and conditional primary secondary cell change (CPC) is lacking, leading to potential data loss and connectivity issues when these processes occur simultaneously.
Innovation Solution
Implementing a dynamic coordination mechanism through extended messages like SgNB ADDITION REQUEST and S-NG-RAN NODE ADDITION REQUEST to indicate whether conditional cell change is prohibited or allowed, enabling the master node to manage CHO and CPC separately, with options for temporary prohibitions and acknowledgments from secondary nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conditional handover (CHO) and conditional primary secondary cell change (CPC) are allowed to occur simultaneously in dual connectivity, then mobility flexibility and network capacity are improved, but data loss and connectivity issues occur due to lack of coordination between the processes
Solution Approach 1:
The master node sends an indication to the secondary node in advance (before the handover executes) to prohibit conditional cell change during the conditional handover process. This preliminary action prevents the harmful simultaneous execution of CHO and CPC, eliminating data loss and connectivity issues while maintaining mobility flexibility.
2Reliability
If coordination mechanism between CHO and CPC is implemented through extended messages, then connectivity reliability is improved, but device complexity increases due to additional signaling
Solution Approach 1:
The coordination indication is merged into existing signaling messages (such as SgNB ADDITION REQUEST or S-NG-RAN NODE ADDITION REQUEST) rather than creating a separate dedicated signaling message. This approach implements reliable CHO-CPC coordination while minimizing additional signaling complexity by reusing established message structures.
3Loss of substance
If the master node sends prohibition indication to the secondary node, then data loss is reduced, but the signaling overhead increases
Solution Approach 1:
The extended message serves multiple functions simultaneously: it adds the secondary node, configures dual connectivity parameters, and conveys the CHO-CPC coordination indication. This multi-functionality reduces signaling overhead compared to separate dedicated messages for each function.
Solution Approach 2:
The prohibition indication is applied selectively only during the conditional handover execution window, rather than permanently. This partial action (temporary prohibition) minimizes the impact on normal CPC operations while sufficient to prevent data loss during CHO.
Data Source
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AI summary
Methods and apparatus, including computer program products, are provided for conditional handovers. In some example embodiments, there may be provided a method including sending, by a first node serving a user equipment, a message to a second node, the message including an indication of whether a conditional cell change is prohibited at the second node; and receiving, by the first node, an acknowledgment in response to the message.