Conditional PSCell Change Handling for MN Reconfiguration Sync
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Solution Overview
Problem
In Rel-17, the standardization of Conditional PSCell Addition (CPA) and inter-SN Conditional PSCell Change (CPC) introduces challenges as the Master Node (MN) cannot determine when to reconfigure itself since the Secondary Node (SN) addition or change occurs at a later time, leading to potential failures in message reception and improper execution of conditional handovers due to mismatched configurations.
Innovation Solution
The MN configures itself for MN/MCG-related reconfigurations by determining and monitoring multiple configurations, receiving heads-up messages from the UE, or transmitting RRC messages with conditional reconfigurations, ensuring it can understand and respond to UE messages on both old and new configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MN configures itself for MN/MCG-related reconfigurations by determining and monitoring multiple configurations, then the reliability of message reception is improved, but the device complexity increases
Solution Approach 1:
The MN performs preliminary configuration by determining multiple possible MN/MCG-related configurations in advance of the actual PSCell addition or change. The network node stores these pre-determined configurations and monitors for UE messages that indicate which configuration the UE has applied, allowing the MN to quickly switch to the correct configuration without real-time computation delays.
2Adaptability or versatility
If the MN transmits RRC messages with conditional reconfigurations, then the adaptability of the handover process is improved, but the loss of time in configuration synchronization increases
Solution Approach 1:
The MN includes MN/MCG-related reconfigurations in the conditional reconfiguration message transmitted to the UE before the actual PSCell addition or change occurs. This allows the UE to have the configuration ready in advance, reducing synchronization time when the conditional reconfiguration is executed.
Solution Approach 2:
The MN creates a copy of the configuration message that includes both the conditional reconfiguration for the PSCell and the associated MN/MCG-related reconfigurations. This copied configuration is transmitted to the UE in advance, allowing the UE to apply the complete configuration set when conditions are met, without requiring additional real-time configuration exchanges.
3Reliability
If the MN monitors multiple MN/MCG related configurations, then the reliability of understanding UE messages is improved, but the device complexity increases
Solution Approach 1:
The MN determines multiple possible MN/MCG-related configurations in advance and stores them for monitoring. When the UE applies a configuration, it notifies the MN, which then compares the notification against the pre-determined configurations to identify the applied configuration, simplifying the monitoring process.
Solution Approach 2:
The UE provides feedback to the MN by notifying which configuration it has applied among the multiple MN/MCG-related configurations. This feedback mechanism allows the MN to verify the UE's configuration state and maintain synchronization without continuously monitoring all possible configurations actively.
Data Source
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AI summary
A method of operating a master node includes determining to configure conditional PSCell addition or change (CPAC). A request is transmitted to a SN to prepare a conditional SN addition, a response therefrom confirms that a UE may be accepted unless a canceling message is later received. A RRC message is transmitted to the UE containing CPAC configurations for candidate target cell(s), where the RRC message contains condition(s) which the UE should monitor and message to be applied when condition fulfilled. Multiple MN or MCG related configurations are monitored for reception of messages from the UE. A message is received from the UE on one of the multiple MN or MCG related configurations monitored. The method detects which one of the multiple MN or MCG related configurations the UE has applied and responsively reconfigures the MN based on the detected one of the multiple MN or MCG related configurations.