Conditional PSCell Addition and Change for Low-Interruption Mobility
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Solution Overview
Problem
Existing wireless communication systems face challenges in ensuring high mobility reliability and minimal interruption during the addition or change of primary cells in secondary cell groups, particularly in scenarios involving dual connectivity and conditional handovers, which are crucial for supporting emerging services with ultra-reliability and low latency requirements.
Innovation Solution
Implementing a novel approach for mobility control through conditional PSCell addition/change (CPAC) that includes coordinated management of candidate PSCells between master and secondary nodes, using inter-node communication protocols like Xn and X2 interfaces, and RRC messages to manage and configure execution conditions and resources efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional PSCell addition/change procedures are used, then network operation is maintained, but mobility reliability is insufficient and interruption time is excessive
Solution Approach 1:
The patent implements conditional PSCell addition/change by preparing candidate PSCells and their configurations in advance before actual handover is needed. The master node receives candidate PSCell information from target secondary nodes, configures conditional handover parameters including execution conditions and resource allocations, and stores this information in the UE's memory. When the execution condition is met, the UE can immediately switch to the pre-configured candidate PSCell without waiting for network signaling, thereby reducing interruption time and improving mobility reliability
Solution Approach 2:
The patent introduces dynamic conditional handover mechanisms where the UE continuously monitors execution conditions (such as signal quality thresholds) and can autonomously trigger PSCell switching when conditions are met. The system dynamically adjusts handover parameters including candidate PSCell lists, execution conditions, and resource configurations based on real-time network status and UE mobility patterns, enabling adaptive optimization of mobility reliability and interruption time
2Reliability
If multiple candidate PSCells are configured for conditional handover, then mobility reliability improves, but device complexity and configuration management become more difficult
Solution Approach 1:
The patent segments the conditional handover configuration into distinct components: candidate PSCell information, execution conditions, resource allocations, and measurement configurations. Each candidate PSCell is independently configured with its own execution condition and resource allocation, allowing the master node and secondary nodes to manage configurations in modular units. This segmentation simplifies the management of multiple candidate PSCells by organizing them into structured, independently controllable elements
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports measurement results and execution condition status to the master node, which in turn adjusts the candidate PSCell configurations and execution conditions. The master node receives feedback on handover execution status and uses this information to optimize subsequent conditional handover configurations. This closed-loop feedback system reduces configuration management complexity by enabling automated adjustments based on actual network conditions and UE performance
Data Source
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AI summary
A master node (MN) may send a secondary node (SN) addition request message to a target SN with an indication of a maximum number of candidate PSCells that can be configured by the target SN. The MN may receive an SN addition request acknowledge message with at least one candidate PSCell configuration from the target SN in response to the SN addition request message. The MN may send, if data forwarding is needed, a data forwarding message with an indication that the data forwarding is for a CPAC based procedure to a source SN. The MN may send a RRC message to a wireless communication device including the at least one candidate PSCell configuration and one or more associated CPAC execution conditions.