Conditional PSCell Change With Secondary Node Switching
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Solution Overview
Problem
Existing wireless communication technologies lack support for Master Node (MN)-initiated inter-Secondary Node (SN) conditional Primary Secondary Cell Change (PSCell Change) procedures, leading to uncertainties in resource allocation, potential failures, and inefficiencies in handover processes due to the MN's inability to generate and manage conditional reconfigurations for target SNs.
Innovation Solution
The proposed solution involves the MN sending an SN Addition Request message to a target candidate SN, receiving an RRC Reconfiguration message in SN format, and then generating a conditional reconfiguration in MN format for the UE, along with execution conditions, allowing the UE to apply the configuration upon fulfilling the conditions, and delaying the release of source SN resources until confirmation is received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MN sends SN Addition Request message to target candidate SN for conditional PSCell Change, then the target SN can prepare resources in advance, but the signaling complexity increases
Solution Approach 1:
The MN sends an SN Addition Request message to the target candidate SN before the actual handover execution, allowing the target SN to prepare resources in advance. This preliminary action ensures that when the conditional handover is triggered, the target SN is already ready to accept the UE, improving handover reliability without requiring complex real-time resource allocation mechanisms.
2Productivity
If the MN generates conditional reconfiguration in MN format for the UE, then the UE can execute handover autonomously when conditions are met, but the configuration management complexity increases
Solution Approach 1:
The conditional reconfiguration is segmented into distinct components: execution conditions (triggering criteria), target cell configuration (SCG configuration from target SN), and action commands (handover execution instructions). This segmentation allows the UE to autonomously evaluate conditions and execute handover without continuous network control, improving execution efficiency while maintaining manageable configuration complexity through structured organization.
Solution Approach 2:
The UE is empowered to autonomously evaluate the execution conditions and trigger the handover to the target cell when conditions are met, without requiring real-time network intervention. The MN provides the conditional reconfiguration with all necessary target cell configurations, and the UE self-services the handover execution by comparing measurement results against the configured conditions and autonomously applying the reconfiguration when triggered.
3Productivity
If source SN resources are released after handover completion, then resource allocation efficiency improves, but handover failure risk increases if released too early
Solution Approach 1:
The source SN resources are not immediately released upon sending the conditional reconfiguration to the UE. Instead, the MN retains control of source SN resources until handover completion is confirmed. This preliminary retention of resources ensures that if the handover fails (e.g., UE cannot access target cell), the source SN resources remain available for re-assignment, reducing handover failure risk while maintaining efficient resource allocation through timely release upon successful completion.
Data Source
AI summary
A method performed by a network node operating as a Master Node (MN) for conditional Primary Secondary Cell Change (CPC) includes sending, to a target candidate secondary node (SN) an SN Addition Request message and receiving, from the target candidate SN, an SN Addition Request Acknowledge message comprising a RRC Reconfiguration message (RRCReconfiguration**) for a target candidate cell. The network node sends, to a wireless device, an RRC Reconfiguration message (RRCReconfiguration), which includes at least one conditional reconfiguration for the CPC. The conditional reconfiguration includes: another RRC Reconfiguration message (RRCReconfiguration*); at least one execution condition for the CPC; and a conditional reconfiguration identity associated with the CPC for the target candidate cell. The RRCReconfiguration* includes the RRCReconfiguration**. The network node receives, from the wireless device, a first reconfiguration complete message (RRCReconfigurationComplete) and a second RRCReconfigurationComplete message (RRCReconfigurationComplete*), which includes another RRCReconfigurationComplete message (RRCReconfigurationComplete**).